The use of topical anesthesia for a combined cataract and glaucoma procedure

Alan S. Crandall

John A. Moran Eye Center, Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences Center, Salt Lake City, Utah, USA

Introduction

Modern cataract and glaucoma surgery represents an amalgam of new techniques that include phacoemulsification, foldable intraocular lenses, clear corneal incision, and two-site combined procedures with clear corneal cataract removal. The fusion of newer techniques has allowed re-evaluation of the anesthetic needs for anterior segment surgery. These minimally incisive surgical procedures have allowed us to reintroduce a very old technique, topical anesthesia, into anterior segment surgery.

Topical anesthesia is not new. In the 1840s, Karl Koller observed that a solution of cocaine applied to the eye could prevent pain during eye surgery. (It appears likely that Koller also introduced Sigmund Freud to cocaine.) With further advances in anesthesia, as well as changes in ocular surgery, general anesthesia and injection techniques became the standard of care. The use of topical anesthesia was reintroduced in the early 1990s with topical 0.5% tetracaine. It soon became obvious that other agents were also acceptable, including marcaine, lidocaine, and lidocaine gel.

Initially, with the use of topical anesthesia only, some patients were not completely comfortable, and some surgeons used intravenous sedation and analgesics to give further comfort. However, in 1995, Gills introduced the use of non-preserved lidocaine (1%) given intracamerally, which provided further anesthesia. In an attempt to evaluate the new procedures, Patel et al. randomized patients to receive a retrobulbar block versus topical anesthesia. A visual pain analogue scale was used to assess pain during surgery. These authors concluded that topical anesthesia can be used safely, and that patient discomfort was only marginally higher postoperatively. The same group then randomized patients to receive topical anesthesia plus BSS versus topical anesthesia plus intracameral lidocaine, and found slight differences between the two groups. They noted slightly better patient cooperation in the group that received the intracameral lidocaine.

Address for correspondence: Alan S. Crandall, MD, John A. Moran Eye Center, Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences Center, 50 North Medical Drive, Salt Lake City, UT 84132, USA

Glaucoma in the New Millennium, pp. 223–233

Proceedings of the 50th Annual Symposium of the New Orleans Academy of Ophthalmology, New Orleans, LA, USA, April 6-8, 2001

edited by Jonathan Nussdorf

© 2003 Kugler Publications, The Hague, The Netherlands

Table 1. Potential complications of injection techniques

Esthetic (conjunctival or lid hemorrhages)

Diplopia

Damage to the extraocular muscles

Retrobulbar hemorrhage

Apnea

Damage to the optic nerve

Ocular penetration

It is now clear that, in routine anterior segment surgery, ocular anesthesia with topical anesthetics will usually suffice. At the present time, we use topical anesthesia for cataract surgery, combined cataract and glaucoma surgery, trabeculectomy, viscocanalostomy, and secondary lens implant, including scleral fixation.

Little has been reported concerning the application of topical anesthesia to complicated cataract extraction, such as when it is combined with glaucoma surgery.

As with cataract surgery, topical anesthesia for phacotrabeculectomy (combined surgery) is an attractive alternative to injection anesthesia, due to the potential for serious complications with the latter method, including globe perforation, retrobulbar hemorrhage, central retinal artery occlusion, orbital infection, chronic mydriasis, optic nerve injury, intravascular or intrathecal injection, respiratory depression, apnea, cranial nerve palsy, and death (Table 1). More common complications with retrobulbar anesthesia include eyelid and subconjunctival hemorrhage, chemosis, postoperative diplopia, ptosis, nausea, and systemic hypertension. Peribulbar anesthesia, although reducing the risk of optic nerve injury, still has the potential for hemorrhage and globe perforation, and requires a greater volume of anesthetic.

In order to determine whether topical medication alone could provide adequate anesthesia for combined surgery, we designed a prospective randomized study comparing topical with retrobulbar anesthesia for phacotrabeculectomy. Specifically, patient comfort and the ability to safely perform the operation were studied. A protocol similar to that of two previous studies was used.

Operative procedures

Preoperatively, baseline vital signs were taken in all patients, and an intravenous line with Ringer’s lactate solution was placed. All patients received topical diclofenac sodium 0.1% (Voltaren) two drops every 20 minutes (two times), phenylephrine hydrochloride 2.5% (Mydfrin), one drop every five minutes (three times); and cyclopentolate hydrochloride 1% (Cyclogyl), one drop every five minutes (three times).

The topical group received two drops of bupivacaine hydrochloride 0.75% (Abbott Laboratories, North Chicago, IL) every five minutes (three times) in the preoperative holding area beginning 20 minutes before the procedure. The bupivacaine used was non-preserved with a pH of 5.4. The method of bupivacaine delivery was the same as the standard protocol used at our surgery center. A separate syringe was used to deliver the bupivacaine to each patient. The retrobulbar group received no anesthesia in the preoperative holding area. In the operating room, all patients received continuous nasal prong oxygen 4 l/min and

baseline vital signs were obtained. Prior to draping, the topical group was given midazolam hydrochloride (Versed, Roche Pharmaceuticals, Nutley, NJ) 0.015 mg/ kg and fentanyl citrate (Elkins-Sinn, Inc., Cherry Hills, NJ) 1 µg/kg intravenously, and an additional two drops of bupivacaine 0.75% were given. Patients randomized to the retrobulbar group were given methohexital sodium 1% (Brevital, Jones Pharma, Inc., St Louis, MO) titrated to unconsciousness (approximate dose 0.5-1 mg/kg) after two minutes of pre-oxygenation with 100% oxygen. With the patient unconscious, a retrobulbar block was performed with a 23-gauge retrobulbar needle using a solution of 2 ml lidocaine hydrochloride 2% (Abbott Laboratories, North Chicago, IL), 2 ml bupivacaine hydrochloride 0.75 %, and 150 U hyaluronidase (Wydase, Wyeth Laboratories, Philadelphia, PA). No ocular compression was performed; neither were facial or eyelid blocks.

Surgery was performed after routine preparation and draping. If, during the surgery, breakthrough pain occurred, supplemental topical bupivacaine 0.75% (two drops) was administered. If this was not effective, fentanyl (0.5 µg/kg) was given intravenously, and repeated after three minutes if necessary. Supplemental block anesthesia was then administered if this was not effective.

A two-site surgical approach was used. An open wire speculum was placed, and no traction sutures were used. Under low microscope lighting, a fornix-based conjunctival flap was fashioned in the superior quadrant initiated by a 5-mm limbal peritomy. Light cautery was used for hemostasis. A 4 × 3 mm trapezoidal scleral flap was then made with a diamond blade, dissecting it into clear cornea with a diamond crescent blade at approximately 70% depth. A Merocel sponge soaked with mitomycin C (Mutamycin, Bristol Laboratories, Princeton, NJ) 0.2 mg/ml was then placed under the flap and left for two minutes, followed by copious irrigation with balanced salt solution. The scope was rotated temporally for the cataract portion of the surgery. After fashioning a 3.2-mm temporal clear cornea incision and sideport paracentesis, sodium hyaluronate (Amvisc) was used to fill the anterior chamber. None of the cases required pupil stretching or manipulation. A continuous curvilinear capsulorrhexis was performed, followed by hydrodissection. Nuclear disassembly was accomplished by a modified phaco chop method, after which the cortex was removed by automated irrigation and aspiration. A foldable intraocular lens was inserted. One radial 10-0 nylon suture was used to close the incision. Acetylcholine 1% was injected into the anterior chamber to constrict the pupil. The scope was rotated again superiorly for completion of the trabeculectomy portion of the procedure. The anterior chamber was entered under the scleral flap using a diamond keratome.

A Crozafon-DeLaange Descemet’s punch was used to make the sclerostomy. A peripheral iridectomy was cut. The scleral flap was then closed with a 10-0 nylon suture at each corner. Viscoelastic was removed from the anterior chamber through the phacoemulsification wound. Adjustable knots were used to allow titration of the flow under the flap. Once the flow was considered appropriate, the knots were tied off and cut. The conjunctiva was then closed using a 10-0 vicryl suture (Ethicon, D-7329, V ASl00-4 needle) in a running horizontal mattress fashion. The conjunctival wound was checked for leakage, and if this was found, the area was oversewn. At the conclusion of the case, a collagen shield soaked in cefazolin (American Pharmaceutical Partners, Inc., Los Angeles, CA) and dexamethasone (American Regent Laboratories, Inc., Shirley, NY) was placed, as well as a drop of atropine 1%. After surgery, the patients were taken to the postoperative area where their

*difference statistically significant

Results

Twenty patients were randomized to each group. Operative conditions and complications are given in Table 2. There was one case of posterior capsular rupture with vitreous loss in the topical group, and one case of posterior capsular rupture without vitreous loss in the retrobulbar group.

Overall patient cooperation, as assessed by the surgeon, was similar for both the topical and retrobulbar groups – rated as excellent in 90% of the topical group and in 85% of the retrobulbar group. No patient in either group was rated as poorly cooperative.

There were no significant differences in the number of patients in either group requiring supplemental IV or topical anesthesia during surgery. No patient in the study required supplemental periocular anesthesia. Inadvertent eye movement was seen more frequently in the topical group (five; 25%) than in the retrobulbar group (none), but did not interfere significantly with surgery in any of these patients. Lid squeezing was noted in four (20%) patients in the topical group versus two (10%) in the retrobulbar group. Chemosis (15 cases; 75%), eyelid hemorrhage (ten; 50%) and subconjunctival hemorrhage (five; 5%) were all significantly higher in the retrobulbar group than in the topical group, in which they were essentially nonexistent. Patient assessment of pain during delivery of the anesthetic showed a slightly higher average score in the topical group. Visual analogue scores produced a mean score of 0.45 for the topical group compared to 0.01 for the retrobulbar group. Fourteen patients (70%) in the topical group and 18 (90%) in the retrobulbar group reported no pain during anesthesia delivery.

There were no differences in the patients’ perception of pain during surgery

Fig. 2. Pain scores recorded for surgery.

(Fig. 2). The mean scores were 0.25 and 0.15, respectively, for the topical and retrobulbar groups. Sixteen patients (80%) in the topical group and 18 (90%) in the retrobulbar group reported no pain during surgery.

Patients reported similar pain scores in the postoperative period (Fig. 3). The mean score for postoperative pain was 0.35 in the topical group and 0.15 in the retrobulbar group. Fifteen (75%) patients in the topical group and 18 (90%) in the retrobulbar group reported no pain during the postoperative period. There was a higher mean score for bothersome touch sensation in the topical (0.2) versus the retrobulbar group. Figure 4 shows the operative conditions as assessed by the surgeon. The conditions were overwhelmingly excellent in both groups, without any significant difference. Overall analogue scores showed a mean of 9.5 in the topical group and 9.6 in the retrobulbar group.

Discussion

Topical anesthesia is growing in popularity for anterior segment surgeons performing cataract extraction. This move is supported by findings of no significant difference in patient perception of pain between topical and retrobulbar anesthesia. Major and minor complications of retrobulbar anesthesia are also precluded by

230 A.S. Crandall

the use of topical anesthesia. Additional benefits include rapid visual recovery without the need to patch the eye in the immediate postoperative period, and a more cost-effective anesthetic regimen.

There has been little published regarding the safety and efficacy of topical anesthesia in phacoemulsification combined with trabeculectomy. Specifically for glaucoma procedures, topical anesthesia has important advantages over retrobulbar or peribulbar techniques. These include avoidance of sudden increases in intraocular and orbital pressure after injection anesthesia, with resultant reduction of optic nerve blood flow and potential exacerbation of glaucomatous optic neuropathy, elimination of the risk of retrobulbar hemorrhage and associated marked elevated orbital and intraocular pressure, and reduction of subconjunctival hemorrhage, which can hinder surgery and is a potential risk factor for filtration failure.

Alternative anesthetic techniques that have been found effective for glaucoma surgery are sub-Tenon’s or subconjunctival injection. For combined phacotrabeculectomy, both Vicary et al. and Anderson reported excellent intraoperative pain control and surgical results with subconjunctival anesthesia. However, subTenon’s/subconjunctival anesthesia is still a form of ‘injection anesthesia’, with chemosis and undesirable subconjunctival hemorrhage extending to more than one quadrant reported to occur in up to 32% of patients. Globe perforation has also been reported with this technique.

Dinsmore found that, while most patients (92% of 136 cases) undergoing cataract extraction only received adequate pain control with topical anesthesia alone, two of five combined procedures and three of five trabeculectomies required additional anesthetic blocks because of pain, most often during conjunctival manipulation and suturing towards the end of surgery.

Our study demonstrates that topical anesthesia alone is an effective alternative to retrobulbar anesthesia for phacotrabeculectomy. We found pain control with topical anesthesia to be equally efficacious as retrobulbar anesthesia, with both techniques resulting in very little pain during delivery of the anesthetic and during and after surgery. The majority of patients in both the topical and retrobulbar groups reported no pain at all. No patient in the topical group required supplemental periocular block anesthesia.

Topical anesthesia provided excellent operative conditions and patient cooperation in 90% of patients, which was similar to the 85% of patients in the retrobulbar group. Most patients in both groups reported not being bothered at all by tissue manipulation or by the microscope light, but touch sensation was more commonly felt in the topical group.

Although there were significantly more patients in the topical group with inadvertent eye movements than in the retrobulbar group (25% versus 0%), this did not appreciably interfere with surgery and, in fact, we found that the ability of patients to follow directions by moving their eye to the desired position during the procedure was helpful in most cases. Our results are not entirely surprising, considering the numerous studies that show topical anesthesia for cataract surgery to be as efficacious as injection anesthesia, without its associated complications. Furthermore, as experience has increased in the use of topical anesthesia, there have been additional reports of topical anesthesia in complicated cataract extractions and in posterior vitrectomies.

Considerations for topical anesthesia in phacotrabeculectomy are different from

phacoemulsification in many ways. Combining glaucoma surgery with phacoemulsification is generally of longer duration, and the use of cautery, scleral incisions, peripheral iridectomy, and conjunctival manipulation and suturing may all cause increased pain. Some surgeons may be uncomfortable with the inadvertent eye movements that may occur with topical anesthesia during the filtering portion of the procedure.

We feel that, compared to routine straight phacoemulsification, strategies to improve patient comfort with topical anesthesia in combined surgery include adequate preoperative counseling, multiple administrations of topical anesthesia starting at least 20 minutes preoperatively in order to allow sufficient tissue penetration, the addition of intravenous sedation for anxiety and additional pain control, and supplemental topical anesthesia when needed, particularly towards the end of surgery when the conjunctival flap is being handled and sutured. We now add lidocaine 2% gel prior to the start of every case, thereby increasing the surface contact of the topical anesthetic, providing excellent analgesia throughout surgery, and reducing the need for supplemental anesthetic.

Intracameral non-preserved lidocaine 1%, which has been found to be a safe and useful adjunct to topical anesthesia in cataract surgery, was not used in this study. We now use this regularly in combined procedures as well and have found it to be helpful, particularly during the creation of the peripheral iridectomy.

Potential questions involve the sedation that was used in the study and that could thus affect patient recall when assessing intraoperative pain levels after surgery, and the fact that different methods of sedation were used for each group. As sedation had to be used for the retrobulbar group, it was decided that both groups would get some form of sedation. Methohexital was used when administering the retrobulbar anesthesia in order to bring patients briefly to unconsciousness while the block was placed. After the block, patients were lightly sedated for the remainder of the procedure, and rarely required additional sedation or analgesia. With the small doses of midazolam and fentanyl used in the topical group, patients were lightly sedated yet awake and cooperative. Using this formulation for the retrobulbar group would have produced an unacceptably high incidence of pain during placement of the block. However, we feel that, after placement of the block in the retrobulbar group, both groups were comparable in levels of consciousness in order to adequately recall intraoperative pain and discomfort levels postoperatively. Identical sedation protocols have been used in similar well-designed studies in the past.

A final concern is that patient pain levels were recorded postoperatively, as opposed to intraoperatively. Although intraoperative recording of pain is ideal theoretically, practically, we feel that some patients are reluctant to ‘complain’ of pain during the surgery, thus introducing a bias in the result. Conversely, recording intraoperative pain levels postoperatively, as collected by an independent observer, perhaps allows for a more accurate response. Furthermore, other indirect measures of patient comfort as recorded by the surgeon, such as patient cooperation and operative conditions as conducted in this study, can provide additional information on intraoperative pain levels.

Caution must be taken when using topical anesthesia in patients with communication difficulties, in those who are deaf or speak a different language from the surgeon, those who are mentally incompetent, and those who are very young or anxious (Table 3). Furthermore, as all patients in this study had primary uncom-

Table 3. Contraindications to topical anesthesia

Relative

language barrier difficult surgery extended surgery time uncooperative patients deafness

Absolute

true allergy to topical anesthesia nystagmus

plicated phacotrabeculectomies, care is also advised when extrapolating these results to patients with scarred conjunctival and scleral tissue, more difficult cases requiring iris stretching, or those with intraoperative complications requiring further manipulation, and with operating times exceeding 30 minutes when patients may report more pain. In this study, the surgeon was experienced in topical anesthesia and was thus able to adjust to this modality for the combined surgery, making minor adjustments in surgical approach and technique. As with any new technique, those not accustomed to topical anesthesia may have a steeper learning curve when adapting to this method.

In summary, both topical and retrobulbar anesthesia provide optimal operative conditions for the surgeon, and excellent pain control for the patient. Topical anesthesia is a safer alternative to retrobulbar anesthesia for combined phacotrabeculectomy since it eliminates many of the potential problems seen with injection anesthesia.

Bibliography

Anderson CJ: Circumferential perilimbal anesthesia for combined cataract glaucoma surgery. Ophthalmic Surg Lasers 30:205-207, 1999

Arnold PN: Prospective study of a single-injection peribulbar technique. J Cataract Refract Surg 18:157-161, 1992

Azuara-Blanco A, Moster MR, Marc BP: Subconjunctival versus peribulbar anesthesia in trabeculectomy: a prospective, randomized study. Ophthalmic Surg Lasers 28:896-899, 1997 Bloomberg LB: Anterior periocular anesthesia: five years experience. J Cataract Refract Surg

17:508-511, 1991

Buys YM, Trope GE: Prospective study of sub-Tenon’s versus retrobulbar anesthesia for inpatient and day-surgery trabeculectomy. Ophthalmology 100:1585-1589, 1993

Crandall AS, Zabriskie NA, Patel BCK et al: A comparison of patient comfort during cataract surgery with topical anesthesia versus topical anesthesia and intracameral lidocaine. Ophthalmology 106:60-66, 1999

David DB II, Mandel MR: Peribulbar anesthesia: a review of technique and complications. Ophthalmic Clin N Am 3:101-110, 1990

Dinsmore SC: Drop, then decide approach to topical anesthesia. J Cataract Refract Surg 21:666671, 1995

Duker IS, Belmont JB, Benson WE et al: Inadvertent globe perforation during retrobulbar and peribulbar anesthesia: patient characteristics, surgical management, and visual outcome. Ophthalmology 98:519-526, 1991

Ellis PP: Retrobulbar injections. Surv Ophthalmol 18:425-430, 1974

Feibel RM: Current concepts in retrobulbar anesthesia. Surv Ophthalmol 30:102-110, 1985 Frieman BJ, Friedberg MA: Globe perforation with sub-Tenon’s anesthesia. Am J Ophthalmol

131:520-521, 2001

Hansen EA, Mein CE, Mazzoli R: Ocular anesthesia for cataract surgery: a direct sub-Tenon’s approach. Ophthalmic Surg 21:696-699, 1990

Jackson K, Vote D: Multiple cranial nerve palsies complicating retrobulbar eye block. Anesth Intensive Care 1998; 26:662-664, 1998

Javitt JC, Addiego R, Friedberg BL et al: Brainstem anesthesia after retrobulbar block. Ophthalmology 94:718-724, 1987

Kaplan LJ, Jaffe NS, Clayman HM: Ptosis and cataract surgery: a multivariant computer analysis of a prospective study. Ophthalmology 92:237-242, 1985

Kershner RM: Topical anesthesia for small incision self-sealing cataract surgery: a prospective evaluation of the first 100 patients. J Cataract Refract Surg 19:290-292, 1993

Kimble JA, Morris RE, Witherspoon CD, Feist RM: Globe perforation from peribulbar injection. (Letter) Arch Ophthalmol 105:749, 1987

Morgan CM, Schatz H, Vine AK et al: Ocular complications associated with retrobulbar injections. Ophthalmology 95:660-665, 1988

Nicholl JM, Acharya PA, Ahlen K et al: Central nervous system complications after 6000 retrobulbar blocks. Anesth Analg 66:1298-1302, 1987

Patel BCK, Bums TA, Crandall AS et al: A comparison of topical and retrobulbar anesthesia for cataract surgery. Ophthalmology 103:1196-2003, 1996

Patel BCK, Clinch TE, Bums TA et al: Prospective evaluation of topical versus retrobulbar anesthesia: a converting surgeon’s experience. J Cataract Refract Surg 24:853-860, 1998

Rainin EA, Carlson BM: Postoperative diplopia and ptosis: a clinical hypothesis based on the myotoxicity of local anesthetics. Arch Ophthalmol 103:1337-1339, 1985

Ritch R, Liebmann JM: Sub-Tenon’s anesthesia for trabeculectomy. Ophthalmic Surg 23:502504, 1992

Roman S, Auclin F, Ullem M: Topical versus peribulbar anesthesia in cataract surgery. J Cataract Refract Surg 22:1121-1124, 1996

Smith R: Cataract extraction without retrobulbar anesthesia injection. Br J Ophthalmol 74:205207, 1990

Stevens JD: A new local anesthesia technique for cataract extraction by one quadrant sub-Tenon’s infiltration. Br J Ophthalmol 76:670-674, 1992

Sullivan KL, Brown GC Forman AL et al: Retrobulbar anesthesia and retinal vascular obstruction. Ophthalmology 90:373-377, 1983

Vicary D, McLennan S, Sun XY: Topical plus subconjunctival anesthesia for phacotrabeculectomy: one year follow-up. J Cataract Refract Surg 24:1247-1251, 1998

Yepez J, Cedeno De Yepez J, Arevalo JF: Topical anesthesia for phacoemulsification, intraocular lens implantation, and posterior vitrectomy. J Cataract Refract Surg 25:1161-1164, 1999

Yepez J, Cedeno De Yepez J, Arevalo JF: Topical anesthesia in posterior vitrectomy. Retina 20:4145, 2000

Update on antimetabolite use

Alan S. Crandall

John A. Moran Eye Center, Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences Center, Salt Lake City, Utah, USA

Antimetabolites have been used to improve the outcome of filtering procedures since the 1980s. Mitomycin C (MMC) is an antibiotic derived from Streptomyces caespitosus. It inhibits DNA synthesis by acting in the late G.I. and early S-phases of the cell cycle. 5-Fluorouracil (5-FU) inhibits fibroblast proliferation.

While these agents have been especially effective in high-risk patients, they are associated with complications. Early complications include corneal toxicity, wound leaks, and hypotonus maculopathy, while late ones include cystic blebs that are dysthetic (painful), blebs that leak spontaneously, and late-developing endophthalmitis.

Over the past few years, modifications in dose and number of injections have been made in order to reduce the long-term complications. Initially, MMC was used at 0.5 mg/ml and was allowed to remain on the eye for as long as five minutes. 5-FU was initially used with subconjunctival injections (180° away from the trabeculectomy site). These injections were given twice a day for one week, and then once a day for a further week.

We know that, in general, glaucoma surgery fails as a result of scarring in the filtering bleb and that antiproliferative agents (both MMC and 5-FU) are associated with a higher rate of success in filtering procedures. In order to maintain a high success rate and to reduce long-term complications, modifications in dose and exposure times have been made. Other modifications have been made in the surgical techniques in order to further reduce complications while maintaining a high success rate.

The ability to use MMC in only one intraoperative application made it the dominant antiproliferative within glaucoma practices. In order to reduce the incidence of thin cystic blebs with their discomfort, leakage, infection, and hypotony, lower concentrations of MMC are used (0.2 mg/ml) and shorter exposure times (I usually use 90 seconds) and I do not use MMC in patients with a high risk of hypotonus maculopathy (Table 1).

Address for correspondence: Alan S. Crandall, MD, John A. Moran Eye Center, Department of Ophthalmology and Visual Sciences, University of Utah Health Sciences Center, 50 North Medical Drive, Salt Lake City, UT 84132, USA

Glaucoma in the New Millennium, pp. 235–236

Proceedings of the 50th Annual Symposium of the New Orleans Academy of Ophthalmology, New Orleans, LA, USA, April 6-8, 2001

edited by Jonathan Nussdorf

© 2003 Kugler Publications, The Hague, The Netherlands

Table 1. Patients with an increased risk of hypotonus maculopathy

Young patients (especially women)

High myopes

Caucasians

In order to improve the surgical outcome, I perform the treatment under the scleral flap and the conjunctival flap. To reduce hypotony, I use a lower dose of MMC and, in addition, take extra care when fashioning the scleral flap. The flaps are slightly larger with smaller sclerotomy, and multiple sutures are used to secure the flap. In order to reduce the cystic blebs and produce diffuse blebs, I use a larger surface area of exposure to MMC.

I use the same sponge each time in order to attempt some reproducibility in the dose of MMC. Within the surgical pack, there is a microwipe corneal shield (Merocel 22-3622), which is 6 mm in diameter. I cut this in half and it then fits nicely under Tenon’s capsule. If 5-FU is given, I reduce the number of postoperative injections and inject the 5-FU near the bleb.

Acknowledgment

Supported in part by a grant from Research to Prevent Blindness, Inc., New York, NY, to the Department of Ophthalmology, University of Utah.

Bibliography

Blumenkranz M, Hernandez E, Ophir A et al: 5-Fluorouracil: new applications in complicated retinal detachment for an established antimetabolite. Ophthalmology 91:122-130, 1984

Chen CW: Enhanced intraocular pressure controlling effectiveness of trabeculectomy by local application of mitomycin C. Ophthalmology 103:1946-1955, 1996

Dreyer EB et al: Effect of mitomycin C and fluorouracil-supplemented trabeculectomies on the anterior segment. Arch Ophthalmol 113:578-580, 1995

The Fluorouracil Filtering Surgery Study Group: Fluorouracil filtering surgery study: one-year follow-up. Am J Ophthalmol 108:625-635, 1989

Jampel HD: Effect of brief exposure to mitomycin C on viability and proliferation of cultured human Tenon’s capsule fibroblasts. Ophthalmology 99:1471-1476, 1992

Kim YY et al: Outcomes of primary phakic trabeculectomies without versus with 0.5- to 1-minute versus 3- to 5-minute mitomycin C. Am J Ophthalmol 126:755-762, 1998

Kitazawa Y et al: Low-dose and high-dose mitomycin trabeculectomy as an initial surgery in primary open-angle glaucoma. Ophthalmology 100:1624-1628, 1993

Prata JA et al: Postoperative complications and short-term outcome after 5-fluorouracil or mito- mycin-C trabeculectomy. J Glaucoma 4:25-31, 1995

Robin AL et al: A long-term dose-response study of mitomycin in glaucoma filtration surgery. Arch Ophthalmol 115:969-974, 1997

Skuta GL, Beeson CC, Higginbotham EJ et al: Intraoperative mitomycin versus postoperative 5- fluorouracil in high-risk glaucoma filtering surgery. Ophthalmology 99:438-444, 1992

Yaldo MK, Stamper RL: Long-term effects of mitomycin on filtering blebs. Arch Ophthalmol 111:824-826, 1993

Plumbing pearls

An effective method for reversing hypotony maculopathy and how to save failing filtering blebs at the slit lamp

Paul Palmberg

Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, FL, USA

The management of hypotony maculopathy

The use of antimetabolites in glaucoma filtering surgery markedly retards the development of episcleral and conjunctival-Tenon capsule fibrosis, with the result that the postoperative intraocular pressure (IOP) depends almost entirely upon the resistance of the scleral flap. Consequently, if the surgeon masters the art of adjusting the scleral flap suture tension to yield the desired IOP at equilibrium flow, he can usually obtain optimal and long-lasting pressure control.1-3

On the other hand, hypotony may result if the surgeon does not have an adequate strategy for preventing it from occurring. This can happen as a result of leaving the scleral flap resistance too low, due to not performing any intraoperative assessment and adjustment of the pressure at equilibrium flow, or from the equally inadequate strategy of using a number of tight sutures in the scleral flap, none of which yield the correct resistance, and then cutting them sequentially, until at last all resistance is undone. Postoperative hypotony also occurs when the wound construction is such that rather tight sutures are needed to yield the desired resistance, and one of them claws through the flap, producing a through- and-through hole over the filtering ostium. If the latter problem is recognized intraoperatively, a partial thickness autologous scleral piece can be suspended with a horizontal mattress stitch over the filtration site (‘abacus bead patch’) with the suture tension adjusted to yield the desired equilibrium pressure (Fig. 1).4

The prevalence of hypotony can also be reduced by employing a valve-like wound construction (‘safety-valve incision’) that yields a pressure at equilibrium flow of about 5 mmHg, and then adding stitches to yield a pressure of 10 mmHg (Fig. 2).1 Additional stitches can be used temporarily to adjust the pressure to 20 mmHg in cases of high preoperative IOP, in order to reduce the risk of suprachoroidal hemorrhage. The advantage of using the safety-valve incision is that, when

Address for correspondence: Paul Palmberg, MD, PhD, Bascom Palmer Eye Institute, University of Miami School of Medicine, P.O. Box 016880, Miami, FL 33101, USA

Glaucoma in the New Millennium, pp. 237–242

Proceedings of the 50th Annual Symposium of the New Orleans Academy of Ophthalmology, New Orleans, LA, USA, April 6-8, 2001

edited by Jonathan Nussdorf

© 2003 Kugler Publications, The Hague, The Netherlands

Fig. 1. Abacus bead patch. A case of hypotony was treated successfully by suspending a patch of half-thickness sclera over the site of filtration, since the partially torn scleral flap (a) could not be repaired with suture alone. A 10-0 nylon suture was anchored in host sclera to one side of the area to be covered (b), passed up through the edge of the patch, across the patch, down through the far edge of the patch, and anchored in host sclera on the other side. The suture was then passed back over the patch and tied with just enough tension to yield a target pressure of about 10 mmHg at equilibrium flow. A second horizontal mattress suture was used to adjust the pressure at equilibrium flow to about 20 mmHg (c). After the resolution of retinal-choroidal folds of hypotony maculopathy, the second suture was cut by argon laser, allowing the pressure to fall to the desired target pressure. (Reprinted from Palmberg,4 by courtesy of the Publisher.)

the nylon sutures in the scleral flap dissolve after about five years, the intrinsic resistance of the wound construction prevents severe hypotony.

When hypotony does develop, it is important to distinguish cases with folds in the macula, ‘hypotony maculopathy’, from those cases without folds. Cases without folds can be treated in fairly conservative ways, such as by placing blood in the bleb or re-suturing the scleral flap, while cases with folds can be repaired successfully with the ‘two sets of stitches’ technique,1 which temporarily raises the IOP to 20-25 mmHg to stretch the contracted sclera and pull out the chorioretinal folds (Figs 3a, b and c). The latter technique has been successful in repairing 25 of 26 cases in which it was used, improving the vision from a mean of 20/100 to 20/ 25, and getting rid of the folds and associated metamorphopsia.

How to save failing filtering blebs at the slit lamp

Blebs fail when the conditions necessary for their continued existence cease to exist. They need a steady flow of aqueous humor to maintain a passageway through the scleral fistula and to distend the interstitial space within the bleb, or else connective tissue cells in the episclera and Tenon’s capsule may bridge across and fill in those spaces. Initial bleb survival is aided when the flow of aqueous maintains sufficient tissue turgor pressure to collapse the conjunctival and Tenon’s capsule blood vessels, and when the aqueous is free of inflammatory cells or flare. Under such conditions, there is little source of serum-derived growth factors to stimulate fibrosis or vascularization, but an adequate nutrient supply to the cells in the bleb.4

Needling of a failing filtering bleb can be done safely and inexpensively at the slit lamp using a 30-gauge needle. The needle is prepared by mounting it on a tuberculin syringe and then bending it into a bayonet shape, using a sterile blade breaker. The bayonet shape allows the needle and syringe hub to be kept away from the lids.5

The eye is prepared by applying apraclonidine 0.5% for vasoconstriction, and then applying proparacaine for anesthesia. After prepping the lids and lashes with povidone iodide, and wiping the excess with a cotton tip applicator, the patient is positioned at the slit lamp and the lids are held open manually or with a speculum.

Failing blebs can often be salvaged if the conjunctiva remains mobile and relatively avascular. Gonioscopy and bleb inspection will have been used to identify the site of aqueous flow obstruction.5-6 If there is a pigmented membrane blocking the internal ostium, a YAG laser can usually apply enough energy to cut through it. But, if the site of obstruction is an episcleral membrane, or if iris is obstructing the internal opening, a 30-gauge needle is likely to be needed. When the site of obstruction is an episcleral membrane, this can be punctured by passing a 30gauge needle into the subjunctival space several millimeters from the edge of the bleb, and advancing it to the scleral flap edge or tunnel mouth (Fig. 4). Visualization may be improved by use of a Ritch lens to compress the overlying conjunctiva and Tenon’s capsule (Fig. 5). The edge of a scleral flap may be identified in difficult cases by using a slit beam to illuminate the sclera next to the site, and watching for the place where the horizontal spread of light in the sclera stops abruptly. The scar tissue in the groove at the edge of a scleral flap does not transmit light as well as an intact sclera does. The needle is passed under the edge of the scleral flap or tunnel mouth and used to elevate it. It the bleb does not inflate, the needle is advanced into the anterior chamber and twisted side to side. Any incarcerated iris may need to be engaged and swept away.

After restoration of the bleb, the needle entry site must be Seidel tested and any leak closed by either pressure with a cotton tip applicator (to compress Tenon’s capsule),10 or with a portable cautery. A stitch may occasionally be needed.

Tenon’s cyst blebs are best treated medically,7-9 although if the pressure cannot be brought to a level that it is thought the optic nerve could tolerate for a few months, then needling could be attempted, and this has been reported to be more successful if an antimetabolite is applied prior to or with performance of the needling.10

Fig. 4. Needling to elevate the scleral flap of an avascular, but failing bleb. A 30-gauge needle, bent into a bayonet shape and mounted on a tuberculin syringe, is passed under the conjunctiva a few millimeters from the bleb margin and advanced between Tenon’s capsule and the sclera to the edge of the scleral tunnel, and then on under the scleral tunnel into the anterior chamber.

Fig. 5. Use of a Ritch laser suture lysis lens to flatten a filtering bleb so that an advancing 30gauge needle can be visualized prior to passage under the scleral flap edge.

A circumferential bleb that is causing tearing and discomfort can be resolved by bleb puncture in the unwanted portion with a portable cautery.

References

1.Suner IJ, Greenfield DS, Miller MP, Nicolela MT, Palmberg PF: Hypotony maculopathy following filtering surgery with mitomycin C: incidence and treatment. Ophthalmology 104:207-215, 1997

2.Scott IU, Greenfield DS, Nicolela MT, Rueda JC, Tsai JC, Schiffman J, Palmberg PF: Interme-

diate-term outcomes of primary trabeculectomy using mitomycin. Ophthalmology 116:286291, 1998

3.Palmberg P: Target pressures. In: The Gullstrand Foundation Meeting, April 1, 2000, Uppsala University. CD-ROM. Sweden: Signal Media AB 2000

4.Palmberg P: Surgery for complications of filtering surgery. In: Albert D (ed) Ophthalmic Surgery: Principles and Techniques, Vol 1, pp 476-478. London: Blackwell Scientific 1999

5.Palmberg P: The failing filtering bleb. Ophthalmol Clin N Am 13:517-529, 2000

6.Greenfield DS, Miller MP, Sunir IJ et al: Needle revision of the scleral flap for failing filtration blebs after trabeculectomy with mitomycin. Am J Ophthalmol 122:195-204, 1996

7.Sherwood MB, Spaeth GL, Simmons ST et al: Cysts of Tenon’s capsule following filtration surgery: medical management. Arch Ophthalmol 105-1517-1523, 1987

8.Scott DR, Quigley HA: Medical management of a high bleb phase after trabeculectomies. Ophthalmology 95:1169-1173, 1988

9.Costa VP, Correa MM, Kara-Jose N: Needling versus medical treatment in encapsulated blebs: a randomized, prospective study. Ophthalmology 104:1215-1120, 1997

10.Mardelli PG, Lederer CM Jr, Murray PA et al: Slit-lamp needle revision of failed filtering blebs using mitomycin C. Ophthalmology 103:1946-1955, 1996

Round table

My procedure and antimetabolite dose of choice for a primary trabeculectomy

Annemarie Etienne, MD, presiding

Panel: George A. (Jack) Cioffi, MD

Alan S. Crandall, MD

Eve J. Higginbotham, MD

Paul Palmberg, MD, PhD

Dr Higginbotham: This was supposed to be a panel on antimetabolites and how we do our trabeculectomy surgery. I could share with you, at least, a tape of one trabeculectomy technique and then we can talk about dosages as well as the questions and answers. This is a patient who has had multiple surgeries. I’d just like to highlight the fact that you have a lot of scarring, and the first step is to choose an appropriate surgical site. This is a patient who had uveitis, had had previous glaucoma surgery as a child, and was aphakic. So she had multiple risk factors for trab failure, as well as being African American. As we took our excursion around the limbus, we chose the most mobile site. The first thing I like to do, since I am often operating on patients who have significant scarring, is to balloon the conjunctiva. I balloon the conjunctiva with 1% lidocaine with epinephrine. This serves two purposes: it shows me where the true scarring is, as well as helping with hemostasis. These patients will often have a lot of bleeding. I then cauterize the incision site and I think you might be able to appreciate that the conjunctiva is a bit leathery. That’s pretty typical of a conjunctiva that has actually had significant surgery before. I tend to try to make my dissection a bit thinner in these instances and not go down to bare sclera, but to really do a subconjunctival dissection, particularly in these instances when the conjunctiva is so leathery. We cauterize aggressively as we go because fibroblasts certainly just love to have a rich environment of blood in which to grow and prosper. I don’t want to encourage them more, and so we will cauterize as we go. I like to use the 23-gauge tapered Mentor tip. One of the things I learned the hard way is that you don’t necessarily want to be aggressive with the conjunctival dissection. That is, if you find yourself having done some conjunctival dissection and there is still some residual scarring here at the limbus, and you are still behind the scleral spur, use your scleral flap dissection as a way of actually carrying you forward into the limbus. Because if you are aggressive, there is a good chance that the conjunctiva is going to turn against you and buttonhole, or thin out, and then you can’t use an antifibrotic

Glaucoma in the New Millennium, pp. 243–255

Proceedings of the 50th Annual Symposium of the New Orleans Academy of Ophthalmology, New Orleans, LA, USA, April 6-8, 2001

edited by Jonathan Nussdorf

© 2003 Kugler Publications, The Hague, The Netherlands

agent. Here, I am about to start my scleral flap dissection. I like to use a 67 blade. You might say that seems a little bit posterior, but I am actually trying to use my scleral flap dissection as a way to get me to the limbus. I like to start my scleral flap dissection before I apply the mitomycin. This allows me at least to let a little bit of mitomycin get underneath the scleral flap so that I can do late laser suturelysis. As Dr Palmberg indicated, we then cut a bit of Weck-Cel sponge and allow it to sit there for the designated period of time. I think, for this patient, because she had had a significant amount of surgery, we did it a little bit longer. I think she probably had 0.5 mg/ml mitomycin C for five minutes, considering the amount of surgery that she had had before. Then you irrigate copiously. I think it is important to remove the diluent. I think this is actually more important than how much water you pour into the eye, but removing the diluent is important. Once I have completed the mitomycin step, I will do my paracentesis. Then we go ahead and do our scleral flap dissection. I try to get at least one-half thickness in terms of depth. Then you can see that I am finally anterior to the scleral spur. You can create your sclerostomy, or alternatively use a Kelly Descemet punch, which I do mostly, but if you don’t have a punch, it is good to know how to remove the window. I do the sides and then I cut the top, open the door, and cut at the base. You like to be anterior to the scleral spur so that you don’t have a lot of bleeding. If you are posterior, then you are going to be in the ciliary body, and that’s not a good thing. Then you go ahead and cauterize the posterior lip and, for me, that helps in two ways. It helps to gape the sclerostomy open more and also to create a theoretical barrier to keep the sclerostomy open. Who really knows, but it certainly is nice to see that sclerostomy gape after that. Then I go ahead and apply sutures, generally four of them, then I simply close with a running Vicryl. This is

atapered needle, BV 130-5, 8-0 Vicryl, bunching up the tissue on a running mattress. At the end of the case, you want to check for Seidel. Of course, it is better to be sure that you have good closure at the time of surgery as opposed to being surprised on the first or second postoperative day, and you are actually looking for

aminor OR to put a suture in. We reform the anterior chamber and then check for Seidel and if this was positive, we can simply go back and put a mattress suture with 9-0 nylon suture.

Dr Palmberg: What was the location of this bleb? I couldn’t quite tell whether the microscope was rotated or something. I really think blebs with mitomycin, as you pointed out, all belong underneath the upper eyelid and not to the sides or down below where you showed eight times as much endophthalmitis. At five years we now have 26% endophthalmitis for blebs down below, and we don’t like that. It’s a small number of patients; six out of 23, large confidence limits, but I just wanted to chime in with what you said about the location of mitomycin blebs, because I would surely put in a Baerveldt if I couldn’t find a spot up top.

Dr Higginbotham: This was a superior bleb and that was a consideration, doing a seton, but because she had not ever had a mitomycin filter, and there was some mobile conjunctiva, we went ahead and did that procedure. What concentrations and durations of mitomycin do you guys use? I think that is one of the questions that is probably coming up.

Dr Palmberg: In a case like this that has had multiple operations, I would use mitomycin C 0.4 or 0.5 mg/ml for a full five minutes, because failure is your biggest concern, and probably in this already partially scarred conjunctiva mitomycin isn’t going to make that go away, so you are going to have very little problem with infection or blebs that are too ischemic, in my hands at least. So here I would go big. Of course, in the primary cases, we are all finding that mitomycin exposure in virgin conjunctiva, perhaps as Allen said, maybe even on combined procedures, less would be used.

Dr Crandall: There is one thing I would do differently. A number of studies have shown that most of the mitomycin is released within the first minute to minute and a half on the sponge. So, in this setting, I would probably have used two or three sponges for about a minute and a half on each sponge, because I think you are getting significantly more mitomycin by using separate sponges.

Dr Cioffi: I actually use multiple sponges as well. I have been doing this over the last year, with 5-FU as well. If I am going to do a 5-FU sponge for five minutes, after a couple of minutes I will replace the sponges with new ones, because I think most of it leeches out in the first couple of minutes and then you are just sitting there twiddling your thumbs, but probably nothing is happening. The same goes for a real scarred eye like this with mitomycin. After a minute to a minute and a half, I may replace some of the sponges. Another thing I do is to use a lot of sponges. I will use three or four sponges in most cases and spread them out over a large area, and I have been much happier since I have been doing this. I think it is part of the reason we see less encapsulations.

Dr Higginbotham: A question for Alan and Jack. Did you change your plan to keep changing the sponges because you were seeing a greater failure rate among your patients, and so is that why you changed your technique? Because I am not sure, maybe Paul you may know, has there been a study looking at changing sponges versus keeping one sponge?

Dr Palmberg: I don’t know of any study.

Dr Crandall: I don’t know of any study either.

Dr Higginbotham: One of my concerns about using multiple sponges is that there was a case presented of a patient who had a residual amount of sponge material left at the time of surgery, and so you can just imagine what happened. There was a huge scleral melt, and even after bringing the patient back and repairing the problem, there was still this ongoing problem with the scleral melt. Any comments on using multiple sponges and just being sure that you remove all of them?

Dr Palmberg: Can you imagine doing a sponge count?

Dr Cioffi: We do. If we use more, we actually keep a sponge count. I actually know of a case here in Louisiana where a retained sponge was found some time after surgery with mitomycin. I try not to use the Weck-Cels because they fragment so much. My main sponge is the corneal protector. I cut it in half so that I have two

half moons. This spreads out over a fair area and often I will just use these two. The Weck-Cels are very prone to falling apart and you have to make sure you have recovered all the fragments.

Dr Higginbotham: Any considerations regarding fornix versus limbal-based flaps? I think that is always a popular question. I will just state, since I have the microphone, that I still like to use limbal-based flaps when I am doing my filters. Now, in the combined procedures I will use a fornix base, but when I am doing my pure filters, I like having those succulent blebs and I like the ability to start my patient on digital pressure early if I need the patient to start. I also like the ability to do laser suture-lysis early as opposed to later. Often, if you do a fornix-based flap, you are going to have that leaking at the limbus. That really slows down any type of real intervention. I try to get my bleb to at least get to two clock hours. That is my goal. Essentially, the principle there is that the larger the run-off, the lower the pressure. Paul, what about you?

Dr Palmberg: I am convinced that you really would like the blebs to spread back more, so I have switched to fornix flaps. If you are doing a fornix flap, the thing that seems important to me is to not have it leak early, to have the eye inflated well enough, to have the pressure at ten at least, because, to make a watertight seal with a fornix flap, you have to have the bleb inflated up, and the conjunctiva pulling down. That brings up the question of titrating your scleral flap resistance. Do you check in the operating room what the pressure feels like? I want to get people to believe in this, because if you make it ten in the operating room, it will stay ten. If you have a 30 with four tight stitches and you cut them all, it will be nothing.

Dr Higginbotham: To be honest, after fifteen years I haven’t.

Dr Palmberg: But do you think it’s a good idea for people who don’t do a lot of filters to at least make sure it is not four to five, or something, with mitomycin, that you know what’s going to happen when you cut the stitches? Because if they are all tight and you cut them all, you will end up with no resistance. I think you should know that you have one or two stitches that correspond to ten, that you’re not planning to cut, and then maybe some more for safety that are tight, but you know which ones they are and you are planning to cut them. I have just found that if I set it at eight to twelve in the operating room, I’ll show you five years later that’s what the pressures are. We cheat like crazy to keep it there. We needle, we cut stitches, we do all kinds of stuff, but if you set it there, mitomycin and 5-FU can make the surgery more predictable by keeping it from changing from the scleral resistance. You are not adding other resistances, so titrate stitches that matter.

Dr Crandall: I do almost all fornix-based flaps, and you are absolutely correct that they have to be sealed, so I use a fairly meticulous closure. It’s a variation on Weiss’s closure. I use a 10-0 Vicryl with a VAS 100-4 needle, and it is a horizontal mattress suture that goes across the wound, and at the end of the procedure, for example, in a temporal approach combined procedure I put the I&A handpiece in and removed the viscoelastic, and it balloons the conjunctiva up hugely. If it can withstand that kind of high pressure, then it is going to be leak-free the next day.

Dr Cioffi: I agree with Eve, I would prefer a limbus-based flap normally, on just my straightforward trabeculectomies. In a case like this, I probably would have gone to fornix, just because of the scar. I find it easier to dissect scar tissue when I do a fornix-based and I can go posterior more easily. Regarding Paul’s idea of titrating the flap. I don’t know if I am converted quite yet, Paul, but when I do mitomycin, I actually label my sutures. I make a little drawing in my chart. I always have the office chart. I label which ones are tight and which are loose. So I know which ones I will laser-lyse later on. I just make myself a quick little drawing of the two or three sutures that I put in and tell myself where I go first to laser-lyse.

Dr Higginbotham: I would like to take advantage of being moderator and have the last word here, and offer some food for thought. If you think about fornix-based flaps versus limbal-based, let’s look at fornix-based. Most of the healing activity is going to be close to your flap, whereas when you are doing limbal base, it is really further removed. Not only do you get a different kind of bleb and you can do things to your bleb earlier than you can with fornix-based, but also, on a theoretical basis, I just wonder if that is something to think about. That’s one reason why we didn’t use a fornix-based flap in this instance, because she had enough scarring. I really wanted to try to locate this filter in an environment that didn’t have a lot of activity. Any questions?

Dr Etienne: The first question is about combination therapy. Given variable nonresponder rates to glaucoma medications, is it important to do one-eye trials, especially with each component of a combination drug?

Dr Higginbotham: That’s a great question. I would like to thank whoever brought it up, because, given the context of the presentation, I didn’t really discuss that. But certainly doing a one-eye trial is very, very important. That wasn’t done in this case because we were really trying to get this guy to think about surgery, I wasn’t really sure if medicines were going to work. Given the diurnal variation that occurs among glaucoma patients, the only way to really know what is going on is to do a one-eye trial. I would certainly encourage everyone to perform oneeye trials.

Dr Etienne: This question is for Dr Crandall. When using lidocaine gel in the preoperative preparation of anterior segment surgery, have you ever had problems with loose corneal epithelium as a result of the gel?

Dr Crandall: No, not loose corneal epithelium, but if it’s been on for a long time, the cornea can develop a haze. This is probably due to the hypertonicity of the gel. So you don’t want it on too long. But I have not had any problems with erosions or breakdown.

Dr Palmberg: Do you put it in the cul-de-sac or over the cornea, or where?

Dr Crandall: Just goop it in.

Dr Etienne: This is for Dr Palmberg. Someone was concerned about cheese wiring with the bleb compression sutures.

Dr Palmberg: In these very thin blebs that we often want to use them in, a 10-0 nylon frequently would work its way down into the bleb. Almost always as it worked its way in, it was Seidel negative. Occasionally it was positive. I find with a 9-0 I get more of the effect I want inside the bleb by creating wide suspenders and less tendency to cheese-wire in, and that is why I have used a 9-0 for several years now. Bob Ritch, who is always going one better, says he uses 8-0.

Dr Cioffi: I have actually done a few of these as well, and I was afraid that they cheese-wired. It is amazing that they sort of settle down and don’t really cut. I have never seen one puncture the bleb.

Dr Etienne: Someone had a question for Dr Higginbotham about the study: why did timolol show iris color changes in this study?

Dr Higginbotham: You can theorize that timolol actually didn’t show iris color changes, just an indication of a negative control and related to the technique that was used to determine if there was iris color change – a false positive. So you could consider your background noise in terms of the patients that actually may or may not have had a change. Just to reaffirm, this is really hard to do. The best way that has been noted to monitor iris color change is to have Polaroid cameras given to every center with the same kind of film, but even then you are going to lose some ability to make these photographs stable across the board. So, timolol doesn’t cause iris color change as far as we can tell. There is no reason why it should. It just gives you an idea of a negative control.

Dr Etienne: To Dr Palmberg, have you ever used TPA (tissue plasminogen activator) in the anterior chamber to remove post-surgical inflammatory membrane?

Dr Palmberg: Yes, and it is quite effective. If you should have somebody with a lot of fibrin in the anterior chamber or even a blood clot, say a neovascular glaucoma that you filtered, using 5 or 10 µg works quite well. People at the University of Illinois, maybe when you were there, published the definitive study on it, showing that 25 µg was probably a little too much and caused rebleeding more often. Were you an author on that?

Dr Higginbotham: We just did a case report of a very small dose.

Dr Palmberg: Then I guess later on there was a series. That is the definitive study. Apparently 10 µg is quite useful. If your bleb is failing early with a blood clot in the ostium, for example, or in the anterior chamber, I would definitely recommend it. It is terribly expensive, though, if you don’t work something out with your pharmacy so that they say, “Take this $1500.00 vial and make up 40 or 50 doses of it and freeze them down”.

Dr Etienne: How far are we from using glaucoma valves as a primary procedure?

Dr Palmberg: We are doing a randomized trial of Baerveldt shunts as primary filtering surgery in Miami. I think the kinds of cases where we are using them primarily on a routine basis are people with the ICE syndrome, children with

glaucoma who did not respond to trabecular surgery, because we really don’t like mitomycin blebs in kids. There is just too much Hemophilus out there. In addition, glaucoma associated with uveitis, where it is active and you can’t suppress it. And what Eve brought up, which I think is just terribly important, is blepharitis. People who have really crummy lids with anterior-posterior blepharitis that you cannot eradicate, I would put in a Baerveldt primarily. You have the tube come in at 12 o’clock and angle it quite nasally and peripherally, it’s not over the lens, they could dilate to 9 mm, it can’t touch, and if you make it through a little tunnel, make a little groove about 1 mm back of the limbus and half thickness to put your 23-gauge needle in. It enters through a tunnel and it can’t flip up into the cornea or down into the lens. You can really control its position very well. We have found this quite good and perhaps particularly beneficial in our young Afro-Caribbean patients in whom even mitomycin filters only work about three-quarters of the time. We have a randomized trial going on now in high-risk, primary glaucoma procedures, and the average pressure in these after several months is about 12 or 13. It is certainly an option, and maybe for the Third World where you can’t do a lot of suture-lysis months or years later, and you can’t see the patients, it’s an operation that takes almost no shepherding. I think that, in the Third World, this would be a wonderful opportunity for dealing with glaucoma.

Dr Cioffi: Paul, 12 or 13, are you using an antimetabolite with that?

Dr Palmberg: No.

Dr Cioffi: That is pretty low. In my hands, I don’t see those low pressures with tubes.

Dr Palmberg: We’re talking about the primary.

Dr Cioffi: I don’t see those pressures with tubes no matter who I put them into, and I generally see them in the high teens. In the patient in whom I am looking for a pressure of 8 or 10, I don’t normally think of a tube as an answer for that.

Dr Higginbotham: It is still pretty early, I would think. What is the follow-up on that?

Dr Palmberg: The primaries that I have done are not out beyond a year. I know that Baerveldt in his complex filter cases had an average pressure of 13.6 at five years. But half those patients were on medication to supplement it, and some of our patients are too.

Dr Cioffi: Even with medications, I haven’t seen that low a pressure.

Dr Palmberg: Obviously, we need some studies.

Dr Etienne: I have a question about Baerveldt valves. Do you feel that there are any indications for the pars plana variety?

Dr Cioffi: Yes. I think Paul talked about one yesterday with the malignant glaucoma patient. If they were having a vitrectomy at the time, I think the most important thing that I have noted is that it has to be a real complete vitrectomy. Because, if it isn’t a good vitrectomy, the peripheral vitreous is going to plug, because vitreous always finds the ostium.

Dr Palmberg: I think it is best to use an MVR blade to make the entry rather than a needle tract, because, with a needle track, you very frequently get stuck in the choroid. Also, don’t turn it at a 90-degree angle, because the tube will kink. You still have to go in at about a 45-degree angle from the surface and you have to visualize this thing in the vitreous cavity, not being blocked by vitreous and not being blocked by uvea before you leave the operating room. You don’t just stick it in and assume it is in the right place. For some reason, when you have a shunt in the anterior chamber of patients with corneal transplants, even if it’s not touching the cornea, there has been a high graft failure rate, 40 or 50%, and so far they are finding only about a 10 or 15% graft failure rate when it is put in the pars plana. This doesn’t make any sense to me. If the aqueous goes from the posterior chamber to the vitreous, it is not feeding the cornea, so posterior placement should be worse. This just shows that nature doesn’t always agree with my guess. So we would encourage you, in those cases where they have had a vitrectomy or are getting one, and they have had a transplant, to consider that. I think the data have gotten good enough now to believe it. I don’t know if it has to do with the immune surveillance or what, but somehow not having the tube in the anterior chamber of a corneal transplant patient seems to be a good idea.

Dr Higginbotham: Paul, how long is the follow-up on those patients?

Dr Palmberg: They are out a couple of years.

Dr Higginbotham: They may be fine early, and later there could be some changes, but that is really impressive.

Dr Palmberg: Well, there is always the curse of long-term follow-up, and failure rates never get better.

Dr Etienne: Do any of the panel members use releasable corneal sutures to secure the trabeculectomy flaps?

Dr Higginbotham: I do on rare occasions, but I still like laser suture-lysis, and the indication for my use of releasable sutures will be in those instances where the conjunctiva is just so leathery that I know there is no way I am going to be able to see through the conjunctiva, then I will use a releasable. But I don’t like them as much, and I feel as if I have more control using the laser suture-lysis. Now that we have these remarkable portable lasers, I think it is easy to have yours carried to a site. So you can actually do laser suture-lysis at some of the satellites.

Dr Palmberg: I’ll make one little plea about this. If you are doing laser suture-lysis and you have an ischemic bleb, don’t use a 50-µm argon spot. You will frequently make a little burn in the tissue, even if you don’t make a hole at the time, and that

adhesion of irritated tissue will stick to the sclera and later, as the bleb grows, it will pull a hole in it, two or three years later. Please use a 100or 200-µm spot size if you are using an argon. You will actually cut the stitch more readily, even though you only have a quarter of the power density, you are treating a longer piece of the stitch. It is easier to hit it, melts well, doesn’t make that little white burn in the bleb, which can make holes later. Or use a red laser, which is wonderful – krypton or diode or something else which doesn’t tend to be absorbed by conjunctiva. So, I think we make a lot of our own endophthalmitis with laser suture-lysis done without taking these things into consideration. I don’t usually like corneal releasable sutures, except in the cases that Eve mentioned, because what if you don’t want to take it out, you still have it. I guess there are clever ways of burying them, but I would rather not have a suture going on into the back and accessible to the surface.

Dr Higginbotham: Does anyone use them? There are colleagues among us who use them a lot. I certainly want to make sure that that perspective is recognized too.

Dr Cioffi: I think a lot of us have gone round in circles and we have tried different techniques and, frankly, I just find them sort of a pain.

Dr Palmberg: I think that the people who do them are those who don’t have a laser in their office and find it very convenient, and obviously that is a consideration. And they do work.

Dr Higginbotham: I will just throw this out for discussion. I think that when mitomycin was being used more commonly across the country and a lot of people were using releasable sutures at the time, that was when we had a lot of hypotony. I think the releasable suture strategy doesn’t give you as much ability to titrate compared to laser suture-lysis. Just a thought.

Dr Etienne: This question is for Dr Crandall. Do you have an anesthesiologist in the room when you do topical anesthesia, just in case you have to convert?

Dr Crandall: Yes, we do. We have nurse anesthetists at the university where I am. We have three operating rooms going. There is one anesthesiologist and three nurse anesthetists. We don’t start IVs any more. They are all given a heparin lock in case they get some sedatives. Just looking at our 7000 cases of topical anesthesia to see what the overall use was, we actually had to convert one out of the 7000.

Dr Etienne: Are the red blood cells necessary for an autologous blood patch to work? Can the autologous blood be spun down and only the serum injected?

Dr Higginbotham: That is an interesting thought, and certainly it is possible that the serum would work. Because it is really the inflammatory components of plasma that we are interested in, and not necessarily the bulk, or what RBCs bring to the table. So, it certainly is an interesting question. But, in most instances, I am doing this in a lane, so I don’t have the luxury of just getting the serum.

Dr Palmberg: I think the fibrin may be important, though, and you are going to lose that if you wait for more than four or five minutes. I am not sure that the serum alone would be too helpful. I don’t find it very helpful for anything, though, to do blood injections. I don’t think it helps a whole lot. I have done it a lot, and the most remarkable results were those patients whose corneal transplant I caused to be rejected, and that’s a relative contraindication to using blood for leaking or over-filtering blebs. The other remarkable result is a case of the same patient who was aphakic, it reactivated their toxoplasmic chorioretinitis and went through the macula. I would definitely suggest not using it in patients with parafoveal toxoplasmosis lesions, or in people with corneal transplants whom you don’t want to expose to their own white blood cells.

Dr Etienne: What do you tell the pharmacy hospital committee when they ask you not to use mitomycin C off label because of liability risks?

Dr Palmberg: We obviously talked to our pharmacy in 1991, and they were very understanding, that a lot of things are used off label. There is no special liability. When the thing has been discussed at scientific meetings, it is well-established, non-experimental therapy. I do not know of any lawsuits based on that kind of argument, having anything to do with either 5-FU or mitomycin. Anybody here?

Dr Higginbotham: I think there is certainly so much literature out there that, in a court of law, you would certainly have the weight of the literature on your side as well as any expert witness who might come in actually to testify on your behalf.

Dr Cioffi: But on that front, I would appreciate whoever wrote that question doesn’t talk to my pharmacist.

Dr Etienne: What about long-term tachyphylaxis to beta-blockers in the use of combination drugs?

Dr Higginbotham: Certainly that would be a consideration in any combination drug that is going to have a beta-blocker. I think, in that instance, it is going to be a decision to either go back to the monotherapy component that might still be effective, or just to tease it out. I think you need to tease it out in a monocular trial with your patient. That is a consideration for any of these beta-blocker drugs.

Dr Palmberg: One thing that I think is very much in favor of beta-blockers being a cornerstone, is that they are stored in the melanin of the eye. Thom Zimmerman and other people have shown that, if a patient is really using it regularly and then they run out of drops for several days, perhaps a week or more, the pressure won’t really rise much. So, it is very forgiving. Xalatan has tissue effects that last for three to five days, and the pressure probably wouldn’t rise for a couple of missed doses if the bottle ran out over the weekend and they didn’t get to a pharmacy. I like those two fairly early, because they are forgiving, and the other drugs aren’t. The other drugs are just gone in 12-16 hours. It’s nice to have at least one of those kinds of drugs in there as a forgiver.

Dr Etienne: What do you do with patients who are allergic to benzalkonium chloride (BAK)?

Dr Higginbotham: That’s a good question. I’m sure that Jack has some comments on this in his role on the update panel, but the only drug that I know of is timolol which comes as a preservative-free formulation, and I am not sure to what extent the companies are encouraged by the issues that we raise as clinicians about the problems we have with benzalkonium chloride. Perhaps this new Alphagan-P or Brimonidine-Purite will provide an alternative.

Dr Palmberg: What does Timoptic XE have? The gel?

Dr Cioffi: Timoptic XE contains BDD (benzododecinium bromide) and I think there is cross-reactivity with benzalkonium chloride. It’s a problem, and the reason we don’t see more alternatives is because it is very arduous for a company to take it through the FDA, if they were going to go with a new preservative. They have to go through all the stability studies and have to show that it is as good as BAK, and so this is one hurdle that most companies aren’t willing to overcome. The single dose timolol is one option. But often there is something that pushes you on to either filtration surgery or argon laser trabeculoplasty.

Dr Etienne: Speaking of filters, if you do a fornix-based flap, what size scleral flap do you create?

Dr Cioffi: A fornix-based flap, what size scleral flap do you create? I don’t actually change my scleral flap, depending on whether it is either fornixor limbus-based. We will hear the panel, but in talking to many glaucoma specialists, I think we have gone toward smaller flaps, 3 to 4 mm flaps. I am not sure it makes that much difference if it is round, triangular, or trapezoidal. I do a trapezoidal flap just because it is what I was taught and it seems to work. I use about a 3 to 4 mm flap in each direction.

Dr Crandall: About 4 mm to probably 2.5 to 3 mm back would be mine.

Dr Palmberg: I use a 3-mm tunnel in all my cases and, if I am teaching residents, I have them go 1 mm farther back and have a little 3 x 1 flap to be forgiving so they don’t cut to the back edge. There really isn’t any point to scleral flaps. The more sclera you cut, the more you have to sew back, and then the more healing you get along the point. You are absolutely right. Wherever you cut sclera, if it doesn’t keep flowing through there, it becomes a scar. So, it just made more sense to me to go 1 mm back of the limbus and make a tunnel, and if I get any scarring it is right down near the limbus, not somewhat farther back.

Dr Higginbotham: I go generally 3 to 4 mm x 3 to 4 mm. I don’t measure any more, and I like square flaps as opposed to triangular flaps, theoretically speaking, because the filtration seems to flow more diffusely out of my scleral flap, whereas the triangular flap seems a little bit on the small side to me.

Dr Palmberg: It goes to one side or the other and you don’t want that. You want the bleb at 12 o’clock. You don’t want it dumping to one side or the other. Triangles have never made any sense to me whatsoever. Also, the stitches in them make no sense because they bite each other. In cutting one, you are actually gaping more until you cut the second one, if they are on the side. From an architectural standpoint, they don’t make any sense to me. They are easy to grab, but that’s the only thing you can say for them.

Dr Etienne: Someone gives a story about a patient who had a bleb needled and then developed long-term choroidals. The eye is quiet, but right after needling the pressure is 4, Seidel negative. Three days later the pressure is 8, Seidel negative, but there is a large choroidal. Two weeks later, the pressure is 11, Seidel is negative, and the choroidal is unchanged. Six weeks, pressure is 11, no change; ten weeks, pressure is 11, no change. What do you do?

Dr Higginbotham: Assuming that the anterior chamber is formed, I am happy actually. I’d like to be sure the patient is using topical steroids. I would even consider stopping the beta-blocker in the fellow eye, get the patient off of any aqueous suppressant. Of course, if they are on a systemic aqueous suppressant for systemic hypertension, there is not much you can do there. But I would just wait it out.

Dr Palmberg: Atropine?

Dr Higginbotham: Well, if the AC is formed, I don’t want to just use atropine, I don’t necessarily use it, particularly in my older men that might have BPH.

Dr Palmberg: We were talking about compression stitches before, which I think are generally useless for hypotony. They only increase tension for the period of time they are present. But this is one case where I think they really do work well if this choroidal is annoying, if it is so big that it is keeping the person from seeing. The choroidal should go away with 11, it is just not fair. If it has persisted for weeks and you are bothered by it enough, then put a compression stitch with an ‘x’ mattress, right over the scleral flap, it just temporarily pushes the scleral flap down and the pressure in the eye will go up to 16 or 18, the choroidal goes away, you cut the stitch out, and the pressure comes back to 11, and you are happy. But I agree with Eve, don’t fix it if it ain’t broken. You would only do this if it was a large choroidal and very persistent, interfering with vision in some way, and it was stalled out after a month or two. But the compression stitch could help you in that way.

Dr Etienne: After six months?

Dr Cioffi: It depends – if it’s annoying. One consideration other than the stitch would just be one of the mega contact lenses that Eve brought up. Sometimes there is just enough compression and you get the pressure to come up 2 to 3 mmHg. It’s weird – in general I tell patients that you are going to hit a magic window around 7 or 8 mmHg, and you are going from seeing crummy to seeing well, your choroidals are going to resorb, and, in general, like you said, it is unfair at 11, in

general everybody has resorbed. It sounds like this patient just needs a little higher pressure. Before the stitch, I would probably try a mega contact lens.

Dr Palmberg: Would anybody put Viscoat or something, a little bit of it in the anterior chamber to try to increase the pressure for a short time? I haven’t done that, I am just curious.

Dr Higginbotham: If the AC is formed, I wouldn’t. I would rather do less with the eye as opposed to more.

Dr Etienne: Does change in the lipid profile with the use of topical beta-blockers worry you?

Dr Higginbotham: On a theoretical basis, it worries me in a postmenopausal woman who is not taking hormonal replacement therapy. That is probably the primary group, as well as anyone who has a significant family history of hypercholesterolemia. I think the difference, at least in one study, there was a 17% depression in high density lipoprotein cholesterol in the timolol group versus 7 or 8% depression in the carteolol. It worries me in those high risk groups.

Dr Etienne: This is the last question. Is Streptococcus pneumoniae resistance to ciprofloxacin a concern for blebitis and endophthalmitis related trabs?

Dr Palmberg: Any Streptococcus is a concern.

Dr Higginbotham: Exactly. I am concerned about the growing resistance we are seeing across the board in terms of these organisms. The last patient I had was only sensitive to a couple of antibiotics. It is pretty scary what is happening out there.

Dr Palmberg: Please don’t use vancomycin for anything except intraocular infections. If people put it in the bottle on all their operations, I think it may eventually come back to hurt us.

Dr Palmberg: I hope we are smarter than the bugs.

Dr Cioffi: It’s a toss up.

Round table

Refractive surgery: thin corneas, inaccurate intraocular pressures, and the myopic disc at risk

Daniel A. Long, MD, presiding

Panel: George A. (Jack) Cioffi, MD

Alan S. Crandall, MD

Eve J. Higginbotham, MD

Dr Crandall: First of all, I think this should be an open forum, because my guess is that the people with the most experience in refractive surgery are not sitting at this table. I do LASIK myself as a glaucoma guy. Most of the LASIK surgeries I perform are post-op cataract refractions, and my requirement is that, if they ask more than three questions, I refer them to the cornea section. So, I have limited experience in that and I think that one of our goals should be to find out how the parameters change when we have done a LASIK or other refractive procedure. I have a number of patients with 16and 32-cut RKs. It is relatively difficult for me to determine their intraocular pressure. My first question to both of the panelists is, are there patients you worry about who have IOPs 20-25 mmHg pre-LASIK? What do you expect to see post-op, and what do you tell them about following their intraocular pressures post-LASIK? What do we expect?

Dr Cioffi: Thankfully, I have talked a number of these patients out of having LASIK, so I don’t have to deal with it too often. It is becoming more and more of an issue for all of us. I think that, in time, we will have some reasonable nomograms that will help with correction, but my gestalt at this point is that it is not a huge change that we are getting in the measured pressure – not really a change in pressure at all, most likely. I am still not convinced that, in an advanced glaucomatous eye, even the brief intraocular pressure rise with the suction ring is a good idea, but I just don’t know. I could suppose a lot of scenarios that, in a tenuous disc, 45 or 60 seconds might be too much at such extreme pressures. In general, for the basic LASIK patient, I don’t think the pressure measurement issue is going to be huge. The real truth is that we now monitor glaucoma less and less by pressure and more and more by fields and optic nerves. So, those are really the parameters that you are looking at anyway, and a pressure can change between 18 and 22 mmHg in ten minutes in your office. I don’t think that we use the guidance of IOP as much as we perhaps once did.

Glaucoma in the New Millennium, pp. 257–268

Proceedings of the 50th Annual Symposium of the New Orleans Academy of Ophthalmology, New Orleans, LA, USA, April 6-8, 2001

edited by Jonathan Nussdorf

© 2003 Kugler Publications, The Hague, The Netherlands

Dr Higginbotham: I think we have to recognize that there is a wide range of individuals out there that people are seeing as eye-care providers and, in some of those instances, pressure is the dominant factor. I still go to screenings and see someone there with their Tono-Pen doing glaucoma screenings. So, what I try to do when I talk to patients is to remind them of the importance of asking the question of whomever they are seeing: how is my optic nerve? To really try to get the patient to help derive the shift in the paradigm. But certainly I think that, for most of us, I agree with you Jack, that we are looking more at the disc and the visual field, and in that context, we won’t miss a lot of patients. But I worry about the broader context of the way people gain access to the health care system.

Dr Crandall: What about the difference? Do you recommend PRK over LASIK, for example, in the moderate and low myopes who are going to have refractive procedures, and have had trabeculectomy and/or are on treatment?

Dr Higginbotham: That sounds like a good discussion, but I do not actually get into that discussion with my patients. I just let them know what we don’t know. We don’t know what is going to happen ten years from now, and I don’t know whether the, albeit small, time that the pressure may be elevated might have anything to do with initiating their apoptotic cascade. We don’t really know that, so I leave it up to the individual, and just let them know what we do and what we don’t know, and then send them off to our cornea specialist who would actually be doing the procedure.

Dr Cioffi: It is my understanding – and I don’t do refractive surgery, one of the guys in our group does – that, because of the suction ring difficulties with the previous trabeculectomy, you often can’t get good suction. I often don’t want them putting a ring on my bleb anyway, then I would probably recommend PRK. Certainly, in patients with blebs that are a –9.00 or something, and you don’t want them wearing a contact lens because of the filtration bleb, I think there are cases that fit into the need for refractive surgery. I don’t discourage it, but in that case, PRK instead of LASIK would probably be the way I would go.

Dr Crandall: Let’s switch to the more common problems that we have. That is, how do you get an accurate reading on someone who has just recently had a corneal transplant? What do you think, and how do you do it?

Dr Higginbotham: Corneal thickness, I think is going to play a more important role in our consideration of glaucoma patients. There are some very interesting data that are about to emerge from the Ocular Hypertension Treatment Study (OHTS). One of these was shared at the Academy, where it was shown that patients who have ocular hypertension have thicker corneas, at least Caucasians have thicker corneas than African Americans. Given what we are learning, not only from the OHTS but also from other studies, about the importance of corneal thickness as it relates to the accuracy of measuring intraocular pressure by applanation, in those instances when I do have a thicker cornea, or high astigmatism, then I tend to go with the Tono-Pen versus applanation. If it is a cornea that I think is within a normal range, then yes, I would just stick with applanation, which I still consider to be the most accurate.

Dr Cioffi: I think the information that Eve was just talking about from the OHTS helps me with patients who don’t have disease. By that I mean the ocular hypertensives who you all see in your offices, who have been ocular hypertensives for the past ten years, and when you get a corneal thickness measurement, they have an unusually thick cornea, which tells you that it is probably an aberration of your measurement. They have been sitting at 23 all this time, and they probably have a fairly normal intraocular pressure, so this gives you yet another reassurance. For patients who have disease, I am not sure that it tells you that much, because it probably doesn’t matter whether their pressure is 18, 20, or 22. It’s got to be lower if that is your goal. For the post-PKP patient, this is a difficult dilemma, especially in a fairly stigmatic eye. I generally do two things: I find the major axis and measure both with and against the major axis, and then I average the pressure between those two and record it as such. Then I also record a TonoPen pressure. But I don’t think there is a great answer. Actually, at a recent grand rounds at our place, one of the residents presented another situation, and that was a LASIK patient who had an unusually low pressure, of 4 or 5 afterwards, and evidently I haven’t seen this, but you can get a little fluid bubble that is maintained between the interfaces. It’s another aberration from corneal surgery.

Dr Higginbotham: I will just add one comment. If you do have a patient who you think has what is called low-tension glaucoma, who may indeed have a thin cornea, I do think it helps to re-set your target pressure. If you are underestimating a pressure because the cornea tends to be on the thinner side, that will give you at least an indication of what might be a reasonable next step for that patient. So I think for those patients who we think might be low tension, I would certainly measure the corneal thickness.

Dr Long: One of the things that came up, and we have a couple of questions here, is about pachymetry on your glaucoma patients. Do you take pachymetry and record that for future reference on all your patients now?

Dr Crandall: No, I don’t.

Dr Higginbotham: I don’t either, but I think certainly as time goes on I will begin to.

Dr Cioffi: Right now, I don’t. In general, I don’t know what to do with the information in that patient I described, with a pressure of 23 or 24, I may get a spot pachymetry, but I don’t in general. If some nomograms are developed along the way, and they show a substantial enough difference – if it is more than a couple of millimeters that we have to correct for – then yes, maybe that would be reasonable to do, but right now we don’t have those nomograms.

Dr Long: Because when you discuss, well they had thin corneas and that may affect their pressures, you have to know whether they are thin or not. How would you know whether they are thin if you didn’t check pachymetry? Someone told me that, in their experience, in all corneas of less than 480-µm thickness, 100% of those patients had glaucoma. Did you ever hear of that? I couldn’t understand how he

would come to that, other than by the fact that maybe a thin cornea means a thin sclera, which means poor support for the optic disc.

Dr Cioffi: I have never heard of that. If it is, in fact, true, whoever this is should share it with us, because we could just screen on that basis. We would probably pick up more. Just do a two-second pachymetry, screen everybody.

Dr Long: It is certainly an easy test to do. The next question about diagnosis of glaucoma is sort of a quality or cost effectiveness question that came up, and Eve, you might be able to lead the discussion on this. How often in a managed care situation, do we need to do visual fields? How fast do you think the visual field is actually going to change? Yes, you don’t want to miss that one person who might lose a little bit of superonasal field, but is it worth doing visual fields on everybody you have every six months or every year, to find the one person that year who may be losing a little bit of field? So how often would you do that, and then we need to explain how often should you be doing gonioscopy?

Dr Higginbotham: Can you give me another piece of information with regard to the context. Are we talking about ocular hypertensive patients?

Dr Long: You have started treatment on someone and they are taking one medication and their pressures are in, say, the high teen range, around 18, 2 or 3 mmHg variation, their visual field test in the first scenario is normal, but they have cupping of 0.7, maybe sector thinning on one side, but they have a normal visual field.

Dr Higginbotham: So they have some structural change, but no functional change in their visual field, so I have made a decision to start them on meds. Primarily because of the meds, I will first of all see them as often as every four months. Then I may do a visual field about every eight months or so. This depends on once I have established that there is or is not a real field defect. Once I have a normal white-on-white, and I generally like to use SITA standard, then I will proceed to do blue-on-yellow, and if I do capture a field defect, then I will certainly confirm that in a subsequent field, perhaps even six months later than the first, because these are patients in whom nothing is happening very quickly. Once I have a confirmed defect, then I may go ahead and repeat the field about every six to eight months after that.

Dr Long: Are there any data to indicate that the patient is going to lose visual field in eight months with pressures of 18?

Dr Higginbotham: There are no data, but we hope that, with the Ocular Hypertension Treatment Study, these will be forthcoming.

Dr Long: You are basically playing the odds, and if the odds are saying that 2 or 4% will lose visual field and you have to select those patients who are going to lose visual field, that is an awful lot of visual fields to be done while searching for that 4% of patients who are going to lose a very small amount of visual field.

Dr Cioffi: But it is our only guide, and I showed you some data earlier that progression rates in treated patients ranged between 4 and 12%, and those were selected articles. Those are the ones I believe. They range up to as high as 20-30%. My rule of thumb is that, in the first year, I get two fields, and for glaucoma change probability plots with the standard white-on-white full threshold perimetry you need two fields to serve as your baseline, because the change probability plots average those as the baseline – that’s done in the computer in ‘Statpac’. I think that same thing will become available in the future, with SITA standard giving baseline data to anchor you. After that, I get fields about once a year – that’s my rule. If I don’t have any suspicion, I get them about once a year. And I think it is valid, even if the number is 5-10%, that is one out of ten patients in whom, if you don’t get fields once a year, you are missing the progression and they are moving on. So, I think that is the whole issue of monitoring chronic disease.

Dr Higginbotham: I’m sorry I missed your lecture Jack, but I think we have to recognize that people progress at different rates too. It is not so much the overall rate, but there are some people who progress at a linear rate, and some who progress at an exponential rate. I would say that, in 15 years of doing this kind of thing, I can think of two patients who progressed significantly all of a sudden. Most of the patients seem to be more of a slow, very insidious rate, but we just don’t know. With all the variability that we see in visual fields in these various studies, I am not sure whether I can necessarily believe a lot of the previous studies in terms of rates of progression of visual fields. Visual fields are very subjective.

Dr Cioffi: I agree with that. I made the point that you need 6-8 to really tell change, and I think we are basically on the same page. I think getting fields at least once a year is the minimum. If it were my mother being treated, that’s how I would treat her.

Dr Crandall: Also, initially, you are not sure whether your target pressure is the correct pressure until you can show that there is non-progression. That is one of things you are trying to establish, I think.

Dr Long: Would you say the same thing about optic disc photographs or disc imaging, if that was your choice, every year, in this mild glaucoma situation?

Dr Higginbotham: Yes, about five years ago I decided to buy the GDX technology, the nerve fiber analyzer, and I generally do that about once a year, certainly. If there is a patient who has been referred to me as a questionable glaucoma suspect, and if they have a normal comprehensive eye examination as well as a nerve fiber analysis, I may not do a visual field every year. I may just do the nerve fiber analysis once a year and just see them clinically without the visual field.

Dr Cioffi: I get baseline photos and then I get photos when I am suspicious, which ends up probably being every two to five years. For a research basis, we have a lot of patients whom we image either every 6 or 12 months with HRT, but that is not really helping me clinically. It is just because we are trying to sort out HRT.

Dr Long: How about gonioscopy? How fast does gonioscopy ordinarily change?

Dr Cioffi: A wide open angle in a myope, if I gonio them every five years, I would say that is a lot. If I had no suspicions or reason, I write down the initial exam. I am pretty qualitative about what I see in the angle, and if I am suspicious, I may gonio them every time I see them, but it may just be a two-second Zeiss-four mirror, it takes just a minute and I am done with it.

Dr Higginbotham: If it is a patient who has been identified as having narrow angles at some point, I will try to do those about once a year, and I would say generally, of course, in a busy clinical practice this parameter unfortunately sometimes gets dropped, but I try to do it at least every two years, particularly considering that I am taking care of a largely African-American population, insidious chronic angle closure is something I worry about. So, I at least try to touch base with the angle, at least periodically, just to be sure that I didn’t miss any new process.

Dr Crandall: About the same. The other group that I like to look at is pseudoexfoliation patients, because I find that their angles kind of tend to change on me.

Dr Long: Let’s talk about this non-penetrating trabeculectomy or surgery. Someone asked the question, have there been any problems with allergic reactions to the implant?

Dr Crandall: No, it is porcine collagen. The real reason for the study in the USA, as I mentioned, was not truly efficacy but safety issues. In none of the studies that I have seen, internationally or nationally, were there any reactions to it.

Dr Long: The person who asked the question made reference to bovine collagen being used in cosmetic surgery to inject in wrinkle lines, and there is a fair amount of allergy with that. But no problems with the porcine collagen? Okay. When you are using the ‘wick’ procedure, any antimetabolites used?

Dr Crandall: In the USA, that was not allowed, it was part of the study. In Europe, yes, they use it in almost every case.

Dr Long: Is this procedure FDA approved in the USA?

Dr Crandall: With conditions. They have to make some changes in terms of what the claim is, and we are starting a randomized trial in the USA, randomized against trabeculectomy with antimetabolites allowed, I think in both groups.

Dr Cioffi: Alan, what percentage of the patients who have had the procedure that has been tested in the USA have blebs?

Dr Crandall: Well most, the ones that work. One of the huge differences between the theory behind Stegman’s procedure and the theory, if you will, behind the collagen, is that in fact you should have a bleb in order for it really to be effective. It is a different kind of bleb. It is low-lying and a little bit thicker. It looks, to a

certain extent, like a non-mitomycin bleb. And Alan Robbin has been overlooking in Stegman’s cases and believes that the ones where Stegman’s worked the best, he also sees a bleb, although Stegman says he never sees a bleb.

Dr Cioffi: I think that is the overwhelming thought – these people do have blebs. So some of the things we think we are getting away from, we may not be.

Dr Crandall: There are a couple of other issues too. If you look at one of the studies I wanted to talk about but didn’t have a chance to is the fact that, in Europe, as many as 46% of the patients over an 18-month period will have what is known as a gonio-YAG to the trabecular descemetocele which then transforms it to a more or less penetrating procedure. I think that is something of an advantage, because it is a bail-out that you can use to lower the pressure at some point in time, and if it allows you to decrease your intraor perioperative complication rate and yet end up with a successful procedure, then it may in fact be a worthwhile procedure. It remains to be seen whether, after five or seven years, there will be a decrease in endophthalmitis and other complications. Those studies have not been done, and I think they need to be done. I think one of the questions then is, you can see the surgery, it’s technical, and is it worthwhile learning that procedure if we are not sure whether it is going to work? I think the answer is yes, because I think it has made us significantly better trabeculectomy surgeons, just understanding so much more about the anatomy of that region. I do believe that you may not want a mitomycin C trabeculectomy running around in underdeveloped countries, but possibly some form of this may be a reasonable thing and perhaps Stegman’s data are not transferable to the USA because we don’t see patients walking into my clinic who are, number one, black, number two, have pressures of 47, number three, are under 30 years of age, who have never been on a drop. That’s the population he operates on. I have seen that because I go to Africa every year. His population is different from ours, and I cannot duplicate his data. My overall success rate with just a viscocanalostomy is not that good. Pressure runs 18 to 21, and I have more failures than I do with my trabs. But the collagen does seem to add a little bit of a bail-out, so I think it will find a place in our armamentarium. It is not going to remove trabeculectomy, but I think it will find a place somewhere.

Dr Long: Well, Dr Crandall, it sounds like you are a proponent of it. How difficult is it to learn, and how difficult is it to find Schlemm’s canal and unroof it, and do all these procedures? How long do you think it takes you to learn that?

Dr Crandall: Do you remember going from intracap to extracap? And then from extracap to phaco? I think it is in that range.

Dr Long: Easy for some, hard for others.

Dr Crandall: Exactly. And I don’t think it’s going to be one for which you watch a video and then just go and do. I think it’s going to be taking a course, just like the phaco courses we all went to because we weren’t being taught in a residency.

Dr Long: Someone asked, okay, I’m trying this and I mess it up and I go straight into the anterior chamber.

Dr Crandall: Then you have done a trabeculectomy. But it is a different kind of trabeculectomy, because if you have done a good posterior dissection, then you are relatively close to the choroid posteriorly. When I am teaching my residents to do it, what I do is have them do the dissection not as posterior, so they are not way over or way back, because I am going to have them convert it to a trabeculectomy anyway. But if I perforate, I wish I had brought videos, because I do. The perforation rate in the first fifty of all the studies I have seen ran to around 15%.

Dr Long: Do you put your collagen implant in then?

Dr Crandall: Yes, I do. It depends on how big the perforation is. It’s not truly the same as a trabeculectomy because you have a large dissection posteriorly, so you have to seal that up.

Dr Long: Eve, you did your residency at LSU, and I know Thom Zimmerman was there at the time, and he was a big proponent of what he called non-penetrating trabeculectomy (NPT). Did you do those back then, and did you do them in your practice? Tell us what your experience was after you got out of practice, how long did you do them, what was your experience with them?

Dr Higginbotham: There are a number of us in the room who tried those procedures, and I just remember sweating bullets in the operating room. Oh my God, did I penetrate or not? As I recall from that experience, there was often a problem with the iris, coming up and adhering to the internal membrane, etc., and it sounds like maybe the modern-day version may have overcome some of these issues, but I am not totally unhappy with my trabeculectomy at this point. So I didn’t actually do this procedure once I left my residency and, as I recall, it was losing popularity even before I finished my residency. I think it is interesting that these ideas have come back.

Dr Long: So you considered it just one of the crazy ideas of your glaucoma professor? I also trained with Thom and a number of people did those. We would all get together or see each other at the AAO meeting, and would say, you know, hey I’ve stopped doing NPTs because they have been failing at a year, and I have a whole bunch of failed filters like that. I am going back to regular trabeculectomies now and they are working a lot better. I think we all kind of came to that, and so that when this procedure came back it was sort of, like, uh oh, here we go again, but maybe there are some improvements in the technique.

Dr Crandall: It’s surgically different from that procedure. I think, that failure of NPT is one of the main reasons why everybody, including myself, in glaucoma is initially sceptical of this new procedure, but it is technically different from Thom’s procedure.

Dr Higginbotham: This is a question that came up with the panel. If this implant actually dissolves at nine months, what is the benefit of it long term, considering that we want this procedure to work long term? Are you suggesting that there are some initial (and if you covered this in your lecture, I do apologize), but is there some initial benefit that kind of carries beyond that nine-month solution?

Dr Crandall: There appear to be a couple of things that may in fact happen. One is that, if you can maintain the lake, just the lake effect may be effective, and that may be why we all have, at least I do, lots of patients with trabeculectomies where I look and look and look and don’t find a bleb, and their pressure is still 12 and it was 24. So, there is that group of patients, where has that fluid gone? Maybe this is a subtle form of cyclodialysis, I don’t know. But, as I mentioned in the lecture, one of the things that is seen, at least in animal studies, is that there are a few increased channels in the area where that collagen was when it was dissolving. Now, why they are there or how they get there doesn’t make a lot of sense in terms of matrix remodeling, but that is a possibility. Once that matrix is there, it seems to stay open, at least in some of the studies that have been done. But in the USA, we only have 28 months and only 190 patients. Everyone in the study – most of us were doing twelve to fourteen, and I went back and looked at my first fifty videos, and then 350 patients later, I looked at my last fifty videos, and I can tell you that, when I looked at the first fifty this time round, I realized how bad I was on those first cases. I thought I was doing a really good job, but I wasn’t even close. I think there is a steep learning curve.

Dr Cioffi: How many people in the audience have done fifty trabeculectomies in the last two years? You are hearing that the learning curve in a guy that does a lot of glaucoma surgery is pretty steep, so take that into account. I think the one other warning is that you destroy a fair area of superior conjunctiva, and I don’t know how easy it is to revisit it if you decide you need to do a trabeculectomy. But my guess is that it’s a pretty big flap.

Dr Crandall: I take down – I measure it in these – I take down 6 mm of fornixbased peritomy and I do them all superonasally.

Dr Long: We have a question here about standard trabeculectomy. Basically, some people will dissect their trabeculectomy flaps forward into clear cornea and enter and make their sclerotomy more into cornea, more anterior, and some will make them right at the iris root. Is there any difference in the results, and if you do an anterior sclerostomy, do you really need to do a peripheral iridectomy?

Dr Cioffi: Do we all do anterior? I do anterior. I essentially do a keratectomy and, when I am teaching fellows, I urge them to do a keratectomy because they are less likely to get into trouble being in over the ciliary body and get bleeding. So, I dissect up into peripheral clear cornea. There are some people, and it may be you, Alan, I don’t remember, who are not doing iridectomies now. I can tell you that a local general ophthalmologist in our city came back from some meeting about four years ago and said that somebody said you don’t have to do iridectomies, and I got a series of about five or six patients over about a two-month period who

had all plugged. As you know, when a trab fails acutely like that they don’t get back to a pressure of 25, they go to 60. So he backed off very quickly, but I think you may not need the iridectomy.

Dr Crandall: Actually, I am one of them. I am selective about it. The question is, do you do peripheral iridectomies? The answer is yes. Do you do them routinely? The answer is no. Number one, I don’t generally do them in combined procedures because the lens is gone and there is tons of room, and I seal them down so, in general, I don’t have problems with shallow chambers. What I usually use as a number is, if somebody is hyperopic, they probably are going to have a PI. If they are myopic, they are probably not. I make the judgment at the time of surgery.

Dr Cioffi: I think the answer is you have to maintain the chamber. It has to be a deep chamber, it has to be tight.

Dr Crandall: If you have somebody who is +7, if you don’t do a PI, you’re dead, right?

Dr Long: Is there any difference in the results as far as failure rates and pressure lowering effect, anterior versus posterior are concerned?

Dr Crandall: I think Dave Apple once looked at the Iowa results over a tento fifteen-year survival when Phelps was there, and they found no difference between the two groups. They found that the more posterior with more bleeding had more complications than the more anterior ones.

Dr Long: Some people are starting to do LASIK on children, anisometropic children who otherwise might be severely amblyopic. Some of these children, we know, have highly distensible optic canals. What would be your feeling about children undergoing LASIK, again with that high pressure of 90 to 100, I guess in my case I would have to say, somewhere between fifteen and twenty seconds of the high pressure? Would you be concerned if this child was also plano on one side and –5.00 on the other side and had 0.6 cupping, healthy rims of course, but a slightly elongated eye?

Dr Higginbotham: This may actually be a good question for Dr Burgoyne to answer, given his studies on the optic nerve. Theoretically, I think children would have more compliance, greater elasticity in the lamina cribosa. I would be less concerned from a theoretical basis compared to an older adult who may actually not have as great compliance. I would recommend a really good informed consent process.

Dr Cioffi: I agree. Theoretically, they are probably safer because of the compliance of their optic nerve. I think older optic nerves are less compliant. I can tell you that, prior to LASIK, back when lamellar keratoplasty was being done with the double cut, I saw one massive choroidal infarct during the suction cup. They did it for a few minutes back then, but it was on a 55or 60-year-old, very prominent attorney in our city, and he was blind, and he was 20/400 in that eye ever after. I think that

not only the disc, but also the retina is at risk in these high myopes. It is not always a healthy eye.

Dr Long: If I threw in the fact that this was one of your patients who is eight years old, had congenital glaucoma, and was under control now, but was buphthalmic on one side and anisometropic, and you were fighting the amblyopia, given that scenario, what would you say?

Dr Higginbotham: In that case, I would discourage the parents from considering it. As long as the pressure is controlled and the nerve looks good, I would just seek out other measures to deal with the amblyopia that are time-tested.

Dr Long: Would you consider PRK instead of LASIK in this situation with the child with buphthalmos?

Dr Higginbotham: I guess I would have to defer to any pediatric ophthalmologist in the room. You have issues with glare. There is pupil size that needs to be considered. I wonder whether those other issues would actually detract from the potential benefit?

Dr Long: The possibility of subepithelial scarring and haze would probably be greater in a child, but I don’t think I have ever run into a discussion of a child having a PRK.

Audience: For Dr Crandall, considering that you say that ‘wick’ procedures work best if you get a bleb, how tightly do you sew down the scleral flaps?

Dr Crandall: Not very tightly. The collagen actually swells fairly quickly, so you place it and then you put a 10-0 suture around it so that it doesn’t migrate, and then you close the flap. Usually, by the time you have finished everything, it has swollen up enough so you can’t really get a great seal around it. In the cartoon, it looks like you do, but it is not a great seal. Maybe that’s why it works. You want a bleb in these things, a low-lying diffuse bleb.

Audience: When do you perform a combined surgery?

Dr Cioffi: I think you’re asking an ethical question, not necessarily a surgical one. Actually, the patient on a single drop, maybe even two drops, who is well controlled and has a cataract, I often just take out the cataract. My discussion with patients is, you have maybe a 5-7% chance of having more difficult-to-control pressure afterwards, but you have probably about a 20-30% chance of having a better pressure afterwards. We don’t really understand why that happens. Whatever the reason, in a lot of patients, especially pseudo-exfoliatives, you take out their lens and they get a better pressure afterwards. Their pressures are easier to control. I think that the discussion of when to do a combined is up in the air, and I don’t think any of us would support doing a combined that doesn’t need to be done.

Dr Crandall: These are not totally benign procedures. You have a reasonable chance of certainly perforating in your first 100 cases, at least a 15-20% chance, so I don’t think that is a good way to learn. If that is the reason behind it, that’s probably not a very wise way to do it. I would say, if you really want to learn it, get a video, try a few, then go and watch, and sit with somebody and go through the procedure, then have them possibly come and sit with you, because it is similar to when you converted to phaco. Remember how those days were.

Dr Long: I think we will have to wrap up the session. Thank you very much for a wonderful discussion.