CHAPTER 18  MEDICAL TREATMENT OF GLAUCOMA  185

KEY POINTS: COMMON SIDE EFFECTS OF TOPICAL GLAUCOMA MEDICATIONS

1.Prostaglandin analogs: Lash growth, iris and eyelid hyperpigmentation, allergic conjunctivitis, macular edema in pseudophakes, flu-like symptoms, and reactivation of herpetic keratitis.

2.β-Blockers: Bronchospasm, bradycardia, fatigue, poor exercise tolerance, depression, and decreased libido.

3.Carbonic anhydrase inhibitors: Stinging, metallic taste, rash, and nausea.

4.Adrenergic agonists: Dry mouth, allergic conjunctivitis, fatigue, and headache.

19.Is there any evidence that lowering intraocular pressure helps treat glaucoma?

Elevated IOP is not only the most important but also the sole modifiable risk factor in the development of glaucoma. Data from randomized, prospective controlled clinical trials such as the Collaborative Normal-Tension Glaucoma Study, the Advanced Glaucoma Intervention Study, the Ocular Hypertension Treatment Study, and the Early Manifest Glaucoma Study all indicate intraocular pressure reduction reduces the number of eyes that have continued glaucoma deterioration. Limited data suggest that the manner in which the pressure is reduced may be important. The Glaucoma Laser Trial found that patients initially treated with laser had less worsening of visual fields than patients who were initially treated with medication. This finding is probably due to the fact that the laser-first group had a 2-mm lower IOP on average, compared with the medicine-only group. On the other hand, the Collaborative Initial Glaucoma Treatment Study found no difference at 5 years of follow-up between medicine and trabeculectomy with regard to the rate of glaucoma worsening. These more recent data seem to support the current general approach that, in theory, it makes no difference how you lower pressure as long as you lower it adequately. There is no consensus as

to how much pressure lowering is adequate. This depends on several factors such as the amount of disease, the rate of change of the glaucoma, the patient’s wishes, and the life expectancy. Most glaucoma specialists would probably agree that, all things being equal, mild disease would require a 25 to 30% IOP reduction, moderate disease a 30 to 40% reduction, and advanced disease a 40 to 50% or more reduction.19-22

References

1.Konstas AG, Stewart WC, Topouzis F, et al.: Brimonidine 0.2% given two or three times daily versus timolol maleate 0.5% in primary open-angle glaucoma, Am J Ophthalmol 131:729–733, 2001.

2.Camras CB, the United States Latanoprost Study Group: Comparison of latanoprost and timolol in patients with ocular hypertension and glaucoma, Ophthalmology 103(1):138–147, 1996.

3.Filippopoulos T, Paula JS, Torun N, et al.: Periorbital changes associated with topical bimatoprost, Ophthal Plast Reconstr Surg 24:302–307, 2008.

4.Russo A, Riva I, Pizzolante T, et al.: Latanoprost ophthalmic solution in the treatment of open angle glaucoma or raised intraocular pressure: a review, Clin Ophthalmol 2(4):897–905, 2008.

5.Brooks AM, Gillies WE: Ocular beta-blockers in glaucoma management. Clinical pharmacological aspects, Drugs Aging 2(3):208–221, 1992.

6.Hayreh SS, Podhajsky P, Zimmerman MB: Beta-blocker eyedrops and nocturnal arterial hypotension, Am J Ophthalmol 128(3):301–309, 1999.

7.Schuman JS: Effects of systemic beta-blocker therapy on efficacy and safety of topical brimonidine and timolol. Brimonidine study groups 1 and 2, Ophthalmology 107(6):1171–1177, 2000.

8.Steward RH, Kimbrough RL, Ward RL: Betaxolol vs timolol. A six-month double-blind comparison, Arch Ophthalmol 104(1):46–48, 1986.

9.Reynolds A: Alpha agonists. In Shaarawy TM, Sherwood MB, Hitchings RA, et al.: Glaucoma volume 1: medical diagnosis & therapy, China, 2009, Saunders-Elsevier Ltd, pp 547–557.

10.Craven ER, Walters TR, Williams R, et al.: Brimonidine and timolol fixed-combination therapy versus monotherapy: a 3-month randomized trial in patients with glaucoma or ocular hypertension, J Ocul Pharmacol Ther 21(4):337–348, 2005.

11.Higginbotham EJ: Considerations in glaucoma therapy: fixed combinations versus their component medications, Clin Ophthalmol 4:1–9, 2010.

12.Motolko MA: Comparison of allergy rates in glaucoma patients receiving brimonidine 0.2% versus fixed-combination

brimonidine 0.2%-timolol 0.5% therapy, Curr Med Res Opin 24(9):2663–2667, 2008.

13. AAO Complementary Therapy Task Force, Hoskins Center for Quality Eye Care: Marijuana in the treatment of glaucoma CTA - 2014, one.aao.org. AAO, June 2014. Web. June 2014.

14.Chua B, Goldberg I: Neuroprotective agents in glaucoma therapy: recent developments and future directions, Expert Rev Ophthalmol 5(5):627–636, 2010.

http://ophthalmologyebooks.com

186  OPHTHALMOLOGY SECRETS IN COLOR

15.Piltz J, Gross R, Shin DH, et al.: Contralateral effect of topical β-adrenergic antagonists in initial one-eyed trials in the ocular hypertension treatment study, Am J Ophthalmol 130:441–453, 2000.

16.Realini T, Fechtner RD, Atreides SP, et al.: The uniocular drug trial and second-eye response to glaucoma medications, Ophthalmology 111:421–426, 2004.

17.Kass MA, Meltzer DW, Gordon M, et al.: Compliance with topical pilocarpine treatment, Am J Ophthalmol 101:515– 523, 1986.

18.Razeghinejad MR, Tania Tai TY, Fudemberg SJ, et al.: Pregnancy and glaucoma, Surv Ophthalmol 56(4):324–335,

2011.

19. Advanced Glaucoma Intervention Study (AGIS): 7. The relationship between control of intraocular pressure and visual field deterioration, Am J Ophthalmol 130:429–440, 2000.

20. Collaborative Normal-Tension Glaucoma Study Group: Comparison of glaucomatous progression between untreated patients with normal-tension glaucoma and patients with therapeutically reduced intraocular pressures, Am J Ophthalmol 126:487–497, 1998.

21.Heijl A, Leske MC, Bengtsson B, et al.: Reduction of intraocular pressure and glaucoma progression: results from the early manifest glaucoma trial, Arch Ophthalmol 120:1268–1279, 2002.

22.Kass MA, Heuer DK, Higginbotham EJ, et al.: The ocular hypertension treatment study: a randomized trial determines that topical ocular hypotensive medication delays or prevents the onset of primary open-angle glaucoma, Arch Ophthalmol 120:701–713, 2002.

1.What are the indications for trabeculectomy surgery?

Trabeculectomy is indicated when neither medical nor laser therapy sufficiently controls glaucoma progression and that progression is likely to diminish a patient’s quality of life. Because visual needs and visionrelated quality-of-life characteristics differ, patients should be assessed individually before a physician decides to perform surgery. Physicians should consider the likelihood of success and risk of complications from surgery prior to proceeding. Trabeculectomy surgery can also be considered as a primary treatment, especially in eyes with severe glaucoma at presentation. Outcomes from a large trial comparing primary trabeculectomy with medication were comparable. A smaller study comparing trabeculectomy with glaucoma drainage devices did not reach conclusive evidence about which technique is best.1-3

2.What is the goal of glaucoma surgery?

The goal of glaucoma surgery is to lower the intraocular pressure (IOP) sufficiently to prevent or minimize further damage to the optic nerve and visual function while avoiding severe complications. The target reduction of IOP will depend on individual factors. In the Advanced Glaucoma Intervention Study, patients with severe glaucoma with an average IOP of 12 mm Hg after surgery had stable visual function after long-term follow-up. Because many patients with glaucoma do not have elevated IOP, the goal of glaucoma surgery is not to reduce IOP to less than 21 mm Hg, but to tailor the pressure to the patient’s needs and characteristics.4

3.How do we inform patients about the risks of trabeculectomy surgery?

The risks and benefits of glaucoma surgery and alternative options must be carefully outlined to all patients in language that is easily understood. It is imperative to explain clearly the remote possibility of blindness or loss of the eye owing to hemorrhage or infection. Discussion should include the possibility of sudden or permanent visual loss, failure to control IOP (which may be too high or too low), the need for repeated surgery, droopy lid, discomfort, and significant blurring (common for the first 2 weeks). Failure to control the IOP and need to restart medication is not uncommon. Other risks include late-onset infection and endophthalmitis (rare) or cataract (common).

4.Describe the factors associated with failure of glaucoma filtering surgery.

Risk factors for the failure of filtering surgery include pigmented skin (nonwhite), younger age, intraocular inflammation, neovascular changes, shallow anterior chamber, previous trauma, dislocated lens, complicated cataract surgery, vitreous in the anterior chamber, inability to use corticosteroids, previously failed glaucoma surgery, previous retinal surgery, scarred or abnormal conjunctiva, and an inexperienced surgeon (Fig. 19-1).

5.Does a fornix versus a limbal–conjunctival approach affect outcome?

Fornix-based and limbal-based approaches produce similar results after trabeculectomy surgery regarding IOP control. With a limbal-based approach the risk of a wound leak is much smaller. However, this incision appears to increase the likelihood of having a thin avascular and localized filtering bleb (Fig. 19-2) and possible bleb-related infections. If a limbal-based flap is chosen, it should be made sufficiently posterior so that the closure is at least 10 mm or more from the limbus. If a fornix-based flap is chosen, it is imperative to ensure that the closure is watertight. There are many ways to close a fornix-based conjunctival flap and it depends on surgeon preference. Most commonly individual 10-0 nylon mattress sutures or a running 8-0 vicryl suture are used. A wet fluorescein strip at the end of the case to check for leaks is useful.

6.What medications should be stopped before filtration surgery?

Patients should continue their systemic medications. Coumadin or other blood thinners do not necessarily need to be stopped. However, it is convenient to confirm that the anticoagulation levels are within therapeutic range for the patient’s condition. If the surgeon desires to stop the Coumadin prior to surgery, it is imperative to discuss this with the patient’s internist, as in some cases stopping may not be advisable because of increased systemic risks.

187

188  OPHTHALMOLOGY SECRETS IN COLOR

Figure 19-1.  Failing filter with increased vascularization and inflammation surrounding the filtering bleb.

Figure 19-2.  Corneal dissection of bleb after a limbal-based trabeculectomy causing discomfort and astigmatism.

7.What are the choices of anesthesia?

General anesthesia is used in children and other patients unable to cope with a local anesthetic procedure. Sub-Tenon’s or subconjunctival anesthesia are our preferred choices. If a surgeon prefers regional anesthesia, peribulbar block is preferred to retrobulbar techniques. A detailed description of our current technique (“blitz” anesthesia) is as follows.

First, Xylocaine 1% jelly or lidocaine hydrochloride 2% jelly is placed in the fornix before surgery. In the operating room, a paracentesis is made temporally and a small amount of aqueous is released from the anterior chamber, followed by an irrigation of 0.1 mL of 1% nonpreserved lidocaine into the anterior chamber through a cannula. Next, inject a 1:1 mixture of 0.1 cc nonpreserved 1% lidocaine mixed with

0.1 cc mitomycin C (0.4 mg/cc). The total volume of 0.2 cc is injected under the conjunctiva with a 30-gauge needle. This precedes the formation of either a limbalor a fornix-based flap. If using this method, additional lidocaine is usually not necessary, but can be used at the surgeon’s discretion. For a fornix-based conjunctival flap, an initial cut is made at the limbus, and 0.5 mL of anesthetic is injected with a cannula under the Tenon’s layer both temporally and nasally. With a limbal-based flap, a 30-gauge needle is used to inject 0.5 mL, 10 mm posterior and parallel to the limbus, ballooning the Tenon’s capsule and conjunctival space in both the nasal and the temporal direction. When closing either a limbalor a fornix-based flap, additional lidocaine 1% is irrigated through the Tenon’s capsule so the patient has no discomfort.

8.Does a triangular versus a rectangular flap affect outcome?

No. The shape of the scleral flap is surgeon-dependent; there is probably no difference in clinical outcome with a triangular or rectangular flap. Although the shape of the flap is not important, its thickness may be. Thin flaps may offer better long-term filtration. However, very thin flaps should be avoided if mitomycin C is used. Regardless of the shape of the scleral flap, sufficient sutures are necessary to be able to control the outflow and prevent overfiltration.

9.Does the size of the internal block affect outcome?

No. A small (e.g., 1 mm) excision is sufficient, although some surgeons choose to create larger fistulas. Increased filtration results when one edge of the internal block coincides with one edge of the scleral flap. The internal block can be removed with Vannas scissors or a punch. Alternatively, a drainage implant under the scleral flap (Express) may be used.

CHAPTER 19  TRABECULECTOMY SURGERY  189

Figure 19-3.  Low diffuse bleb with releasable suture in place 1 week following a trabeculectomy.

10.Are iridectomy and paracentesis always necessary during filtration surgery?

An iridectomy is always performed in angle-closure glaucoma to ensure that pupillary block does not occur. In addition, if the chamber shallows, the iris is less likely to occlude the ostium. However, iridectomy may not be necessary in patients with open-angle glaucoma and particularly in pseudophakic eyes. A paracentesis is always done, and it can be made with either a sharp blade temporally or a 27-gauge needle on a syringe. A paracentesis is considered essential with each procedure because

it allows re-formation of the anterior chamber toward the end of surgery. By refilling the anterior chamber via the paracentesis, the surgeon has an appreciation of how much leakage is visible around the edges of the scleral flap.

11.How tight should I make the scleral flap?

The number of sutures and their tightness depend on the diagnosis, preoperative IOP, architecture of the scleral flap, location of the fistula, and how much leak is desired at the time of surgery. In general those patients at high risk for complications associated with hypotony should have tighter

scleral flaps. For example, patients with inordinately high IOP, shallow anterior chamber, angle-closure glaucoma, aphakic glaucoma, or increased episcleral venous pressure are more likely to develop complications if there is overdrainage.

With low-tension glaucoma, looser sutures with more flow may be indicated to ensure a low initial postoperative intraocular pressure. The sutures can be lysed with an argon laser anywhere from day 1 through the first 2 weeks or longer if antimetabolites are used.

12.Are releasable sutures necessary?

Although releasable sutures have some advantages, they are not necessary to achieve a good result. We tend to use additional releasable sutures as they allow tighter closure of the scleral flap, avoiding hypotony, and because of the ease with which they can be removed at the slit lamp (Fig. 19-3). The flap can be closed moderately loosely with permanent sutures, and the releasable sutures decrease the flow further. Selective removal between the first postoperative day and 1 month can easily be done at the slit lamp.

13.Does it matter how far I dissect the scleral flap anteriorly?

We aim to open the fistula anterior to the trabecular meshwork. In large myopic eyes, a perpendicular incision just anterior to the corneoscleral sulcus carries the flap well anterior to the trabecular meshwork. In removing the internal block, a satisfactory fistula results. In contrast, in small hyperopic eyes and those with angle-closure glaucoma or peripheral anterior synechiae, an incision at the same point terminates just in front of the iris root. In these patients, an anterior dissection well into the cornea is necessary both to ensure that the fistula will not be blocked by uveal tissue and to prevent bleeding (Fig. 19-4).

14.Should atropine be used during the procedure?

Atropine is needed only in patients with small eyes, shallow anterior chamber, or angle-closure glaucoma. Sterile 1% atropine drops are placed on the cornea to dilate the pupil maximally and to move the lens–iris diaphragm posteriorly. This technique decreases the likelihood of a flat anterior chamber in the early postoperative period.

190  OPHTHALMOLOGY SECRETS IN COLOR

Figure 19-4.  Spontaneous hyphema following a trabeculectomy in a 40-year-old woman with chronic angle closure and with no other risk factors.

Figure 19-5.  Flat anterior chamber, grade II (contact between peripheral and central iris and cornea), and resultant cataract following a trabeculectomy.

15.How often are steroids used in the postoperative period?

It varies according to the surgeon’s preference and the apparent inflammation, but at a minimum they should be used four times/day for at least 1 month (e.g., prednisolone acetate 1% or betamethasone 0.1%). In phakic eyes, topical steroids are tapered quickly after 4 to 6 weeks to reduce the risk of cataract. In pseudophakic patients or eyes with signs of increased conjunctival or intraocular inflammation, the steroid treatment can be intensified and maintained for 2 to 3 months. Some surgeons prefer the addition of a nonsteroidal anti-inflammatory drug one time/day in conjunction with the steroids over a 1 to 2-month period. A commonly used regime is to taper steroids every 2 weeks for a period of 8 weeks. Typically, four times a day for 2 weeks, three times for 2 weeks, etc., down to “off.”

16.How can you avoid a flat anterior chamber after trabeculectomy?

The most useful strategy is to prevent overdrainage and hypotony. The amount of leakage underneath the scleral flap ultimately determines the postoperative pressure. To minimize the chance of a flat anterior chamber (Fig. 19-5), additional 10–0 nylon sutures, with or without releasable sutures, should be used to minimize the flow at the end of the procedure. Laser suture lysis may then be used to increase selectively the flow under the scleral flap and improve control. If the sutures are cut too aggressively, a flat anterior chamber may result.

17.What do you do when a wound leak occurs in the immediate postoperative period?

Unless the leak is very brisk, it usually heals within the first few days. If the leak is near the limbus, either a collagen shield or a bandage contact lens may help. If a leak is very brisk or associated with a flat filtering bleb or with a shallow anterior chamber, surgical closure is necessary. If the leak is located at the wound, restitching is required. If there is a buttonhole, a purse-string knot with a rounded-body 11-0 nylon is very helpful. It is useful to use a fluorescein strip to confirm that the wound and buttonhole are Seidel negative before ending the procedure.

http://ophthalmologyebooks.com

CHAPTER 19  TRABECULECTOMY SURGERY  191

KEY POINTS: HOW TO AVOID COMPLICATIONS OF TRABECULECTOMY

1. Identify high-risk conditions (e.g., angle-closure, elevated episcleral venous pressure, previous conjunctival surgery).

2. Avoid hypotony with proper suture technique of the scleral flap (with or without releasable sutures). 3. Use paracentesis to evaluate the amount of filtration under the scleral flap and decide whether more

or fewer sutures are required.

4. After closing the conjunctiva, inject balanced salt solution into the anterior chamber to raise the bleb and confirm the absence of leaks.

Figure 19-6.  Sponge soaked with mitomycin C placed under the conjunctiva and Tenon’s capsule prior to making the scleral flap.

18.What do you do if there is vitreous loss at the time of the trabeculectomy?

A “dry” vitrectomy (without balanced salt solution (BSS) infusion) with viscoelastic can be very helpful. It can be done through the scleral flap and peripheral iridectomy. If an inordinate amount of vitreous is present, it is probably best to proceed with a full anterior vitrectomy. Vitreous loss is rare in phakic eyes that have no history of trauma, surgery, or other predilection toward lens dislocation. Vitreous loss is more frequent in eyes that are aphakic or pseudophakic in the presence of zonular weakening (see next question).

19.What ocular conditions may predispose to vitreous loss during trabeculectomy surgery?

Preoperative conditions such as ocular trauma, Marfan’s syndrome, pseudoexfoliation, homocystinuria, complicated cataract surgery, and high myopia may predispose to vitreous loss during trabeculectomy surgery.

20.Describe the indications for antimetabolites in trabeculectomy surgery.

Most surgeons routinely use mitomycin C in trabeculectomy surgeries. Both 5-fluorouracil and mitomycin C inhibit normal wound healing and facilitate the formation of highly functioning filtering blebs (Fig. 19-6). Although current antifibrotic agents have improved surgical outcomes, their associated complications should be considered. The use of antimetabolites is more important in eyes at high risk of failure, e.g., scarring of the superior conjunctiva, previously failed filters, younger age, pseudophakia, ocular inflammation, or advanced optic nerve and visual-field injury with desired postoperative pressure less than 14 mm Hg.5

21.How does 5-fluorouracil differ from mitomycin C?

Mitomycin C (0.1–0.5 mg/mL) is 100 times more potent than 5-fluorouracil (5-FU; 25–50 mg/mL). Whereas 5-FU affects primarily the S phase of the cell cycle, mitomycin C inhibits fibroblastic proliferation regardless of the phase of the cell cycle. Most surgeons prefer intraoperative mitomycin C. Intraoperative application is done with several Weck-cell sponges on the sclera under the conjunctiva and Tenon’s capsule, treating a large area of the superior globe. The sponges are left in place for 1–5 minutes depending on the perceived risk of failure. Alternatively mitomycin C can be injected subconjunctivally (0.2–0.3 mL) at the beginning of the surgery.

192  OPHTHALMOLOGY SECRETS IN COLOR

Figure 19-7.  Hypotony with chorioretinal folds at the macula. IOP was 4 mm Hg.

Figure 19-8.  Suprachoroidal hemorrhage 1 week after filtering surgery in a patient with known heart disease, valve replacement, on blood thinners.

Figure 19-9.  Leaking bleb following a mitomycin C trabeculectomy 6 months after surgery.

22.Are antimetabolites indicated in primary filtering procedures?

It depends on the surgeon’s choice, but most surgeons use mitomycin C for primary trabeculectomy. With modern surgical techniques postoperative complications of hypotony (Fig. 19-7), suprachoroidal hemorrhage (Fig. 19-8), choroidal detachment, flat anterior chambers, and bleb leaks (Fig. 19-9) are uncommon, and late endophthalmitis (Fig. 19-10) is rare.

23.What do you do when the iris blocks the trabeculectomy site in the immediate postoperative period?

One option is to place Miochol via the paracentesis into the anterior chamber in an attempt to constrict the pupil and dislodge it from the trabeculectomy site. A viscoelastic agent is then injected, and either a cannula or a 30-gauge needle can be used to remove the iris carefully from the trabeculectomy site. On occasion, the iris does not occlude the ostium completely, and good filtration may occur around it.

CHAPTER 19  TRABECULECTOMY SURGERY  193

Figure 19-10.  Endophthalmitis following a trabeculectomy resulting in poor vision.

Figure 19-11.  Superficial punctate keratopathy following repeated injections of 5-FU in a failing filter.

24.What if the ciliary processes roll anteriorly and block the trabeculectomy site during surgery?

Ciliary processes may block the trabeculectomy site in small hyperopic eyes, chronic angle closure, and nanophthalmos, especially if the fistula is not done anteriorly to the trabecular meshwork. After the fistula is done, the ciliary processes may roll into the filtering site. In most cases, closing the scleral flap, re-forming the anterior chamber, and reestablishing normal anatomy allow the ciliary processes to revert to their normal positions. If, after deepening the anterior chamber, the ciliary processes continue to block the trabeculectomy opening, they can be cauterized and cut away. Care must be taken not to disturb the vitreous face.

25.When is it necessary to give postoperative 5-fluorouracil injections?

Supplementary 5-FU injections, e.g., 0.1 mL (5 mg), may be given in the early postoperative period if the bleb is thickened, red, and vascularized. This option is left to the surgeon’s discretion. This

treatment is to decrease the chances of bleb scarring and failure. When repeated injections are used, corneal epithelial toxicity may appear and should be monitored. If there are signs of keratopathy, 5-FU injections should be delayed (Fig. 19-11).

26.What do you do if the bleb starts to fail?

If the bleb is thick, and injected, an increase in the topical steroid regimen and 5-fluorouracil injections is indicated. In addition, 2.5 mg of bevacizumab (Avastin) can also be injected into the bleb. Digital massage in the early postoperative period increases the outflow, but it is not effective in the long term to maintain the bleb function. Aggressive suture lysis should be considered. Sometimes, regardless of all efforts, the bleb fails and further glaucoma surgery may be required. Alternatively, bleb needling can be tried (see next question).6

KEY POINTS: HOW TO IMPROVE YOUR SUCCESS RATE

1. Use intraoperative mitomycin C.

2. Use postoperative 5-fluorouracil when the bleb shows early signs of scarring and failure. 3. Cut or release sutures when the function of the filtering bleb is suboptimal.

4. Consider needling with 5-fluorouracil or mitomycin C when the bleb has failed.

194  OPHTHALMOLOGY SECRETS IN COLOR

27.What is the technique of bleb needling?

Needling can be done in the operating room or at the slit lamp. A sterile technique is required, including the use of topical diluted Betadine. Sub-Tenon’s or subconjunctival anesthetic, associated with either 5-fluorouracil or mitomycin C, is injected. A mixture of 1:1 lidocaine 0.1 cc and 0.1 mitomycin C (0.4 mg/ cc) can also be injected first with a 30-gauge needle before the needling. The mixture is dispersed widely

over the surgical area. After waiting a few minutes, needling can proceed. It is important to detect where the resistance to filtration is occurring. Most often, scarring at the scleral flap is responsible for bleb failure. In this case a 27-gauge needle is introduced into the subconjunctival space 8–10 mm away from the scleral flap, directed toward the flap edge, and, if possible, advanced under the scleral flap to ensure an outpouring of aqueous. The surgeon can try to maximize the efficacy of the bleb revision with some careful movements of the needle. Postoperative topical antibiotics and steroids are used. Although the needling procedure can be done at the slit lamp, we now prefer needling in the operating room, as the situation is more controlled, bleeding can be handled more easily, and everything is done under sterile conditions.7

28.What is the differential diagnosis for a flat anterior chamber?

The most common cause of a flat chamber after glaucoma surgery is excessive filtration. Other possibilities include serous choroidal detachment, hemorrhagic choroidal detachment, pupillary block, and malignant glaucoma (Table 19-1). With excessive filtration and serous choroidal detachment, the IOP is low. With a hemorrhagic choroidal detachment, the IOP may be low, normal, or high and usually is associated with pain. With both pupillary block and malignant glaucoma, the IOP is typically elevated and the cornea often edematous.

29.How urgent is the management of a flat anterior chamber?

Grade I (contact between the peripheral iris and the cornea) can be managed conservatively. If it is due to overfiltration, treatment includes the use of cycloplegics and mydriatics and careful observation. Improvement is usually spontaneous. Progression from grade I to grade II (contact between the peripheral and the central iris and cornea) despite treatment may be a poor prognostic sign, especially if the pressure is falling and the bleb is flattening. Grade II may recover spontaneously or progress to grade III (contact between the corneal endothelium and the lens). Grade III is an emergency and must be corrected promptly or the corneal endothelium will be damaged.

30.What are the indications to drain a choroidal detachment?

Drainage of the associated choroidal detachment is indicated whenever the pressure consistently falls, the bleb flattens, and the chamber shallows despite re-formation with viscoelastic material. Appositional “kissing” choroidal effusions that do not improve after a few days to weeks should also be drained (Fig. 19-12). A full-thickness scleral incision is made in one of the inferior quadrants to reach the suprachoroidal space. Re-formation of the anterior chamber is done simultaneously with BSS through the paracentesis tract. If the choroidal detachment is determined to be hemorrhagic, it is recommended to wait at least 10 days before drainage so that the blood can liquefy.

Table 19-1.  Prevention of Malignant Glaucoma (Aqueous Misdirection)

1.Detect high-risk cases (angle-closure glaucoma, small, hyperopic eyes).

2.Minimize intraoperative shallowing of anterior chamber.

3.Perform a large peripheral iridectomy.

4.Avoid overfiltration.

5.Cautious suture lysis.

6.Use cycloplegics. Taper cycloplegics slowly.

Figure 19-12.  Ultrasound of kissing choroidals following a filtering procedure in an eye with chronic angle closure.