Ординатура / Офтальмология / Английские материалы / Glaucoma Surgery_Trope_2005

3.3.Observation

Observation is justifiable if the patient has previously been doing very well and there was a precipitating event. On occasion, a patient will have suffered a blow to the eye followed by a leak. In addition, some patients will recognize that eye rubbing during sleep is a problem. In both cases, a shield at bedtime may allow the leak to heal over a matter of weeks. Antibiotic coverage, although controversial, should be considered either for the duration of the leak or for the immediate administration at the first signs or symptoms of blebitis (pain, discharge, reduced vision, redness). Aqueous suppressants may decrease flow and help the leak to seal. We do not recommend patching at this time as the patch compresses the eye, increasing flow through the leak. If the leak is not resolved within 2 3 weeks, we recommend expedited incisional correction of the leak.

3.4.Nonincisional Correction of the Bleb Leak

Surgical correction of bleb leaks can be broken down into two categories: nonincisional and incisional. Suggestions for nonincisional maneuvers include patching, bandage lenses, laser, cryoacrylate glue, autologous fibrin tissue glue, and autologous blood injections.

Initial reports using blood injections for bleb leaks showed promise with resolution of leakage in four of seven eyes and four of six eyes, respectively (4,5). In a larger series of patients reviewed by Burnstein (6) and Choudhri (7), the results were less positive. Burnstein reported that 72% of 32 eyes failed outright and for the remaining nine eyes, bleb leaks recurred in 33%. Asrani (8) described the use of autologous fibrin tissue glue. In their study, different medical maneuvers were tried including fibrin tissue glue. Success was achieved in nine of 12 patients in the fibrin tissue glue group and, interestingly, overall only 31.4% of 35 leaks did not respond to nonincisional treatment. Geyer

(9) used the continuous wave Nd:YAG laser with some promising results.

3.4.1.Technique

The technique for autologous blood injection is very simple. It involves drawing 1 mm of blood from an arm vein, changing to a 30 gage needle, and then immediately inserting the needle under direct vision into anesthetized subconjunctiva 1 2 mm from the bleb. The needle is then advanced into the bleb area. The blood is then released into the bleb, filling the bleb itself. It is important to warn the patient that this procedure can result in blood reflux through the ostium into the anterior chamber causing temporary (up to 10 days) vision loss.

Burnstein (10) retrospectively compared surgical conjunctival advancement to nonincisional techniques in a review of 51 patients between 1986 and 1999. The bleb leaks occurred at least 2 months after trabeculectomy. Success was defined as resolution of bleb leak and intraocular pressures ,21 mmHg. Nonincisional treatment was successful in only 32% of cases (12 of 37 eyes). Of the 34 eyes in the surgical conjunctival advancement group, 100% had closure of the leak but leak recurrence eventually developed in two patients and 11 required glaucoma medication.

3.5.Incisional Repair of Bleb Leaks

As bleb leaks and hypotony occurred more frequently throughout the early 1990s, the need for better correction of the problem became more apparent. Initially, there was some reluctance to excise a filtering bleb, as there was concern that the glaucoma control would be

lost. With experience, we have realized that despite bleb revision, glaucoma control is maintained in the majority of cases (11 20). We, therefore, feel the best and most appropriate approach to late bleb leaks is expedited surgical repair of the leak depending to some degree on the clinical questions as outlined in Introduction.

3.5.1.Options for Incisional Repair of Bleb Leak

For the most part, the techniques involve the same principles. The choice of conjunctival repair initially depends on conjunctival availability/mobility at the time of surgery. For pedicle/conjunctival advancement, enough conjunctiva must be available behind the bleb to allow for advancement over the existing bleb site. If the bleb is large and/or surrounding conjunctiva is adherent to underlying sclera, an autologous flap should be used.

Management of the Existing Bleb. The existing bleb can be managed by either de-epithelialization, using mechanical scraping or alcohol, or by total excision of the bleb. Good results have been reported in literature using either technique, but we prefer not to remove the total bleb. We de-epithelialize the existing bleb with an alcohol prep and for the most part do not attempt to repair the scleral flap. Some clinicians, however, evaluate the trabeculectomy flap at the time of excision to determine whether patch grafting is necessary. It would also be reasonable to consider scleral re-enforcement if the eye is hypotonous without a leaking bleb. Re-suturing the sclera has not proven to be satisfactory, thus necessitating grafting of donor sclera, donor pericardium, or autologous tenons to increase resistance. LaBorwit (19) found autologous tenons the most satisfactory material, but Kosmin (20) achieved good results with donor sclera.

Conjunctival Repair. Conjunctival repair can be broken into two stages: preparing recipient tissue and mobilizing the conjunctiva for patching. Initially, dissection is done around the bleb undermining the conjunctiva to ensure adequate mobility. The peripheral cornea must also be prepared. Although some authors proposed lamellar keratectomy, we, as well as many others, feel that a simple debriding of the epithelium at the peripheral cornea will allow the conjunctiva to stick. Conjunctival mobilization can be done by advancement, pedicle grafts, or autologous autografts. After the conjunctiva has been mobilized, it can then be sutured into place using either wing sutures or continuous sutures. We prefer continuous suture of 9/0 nylon, 9/0 vicryl, or 10/0 nylon.

Conjunctival Advancement. If the conjunctiva is very mobile and the bleb is small, a simple mobilization of the conjunctiva can be performed. If the conjunctival flap is noted to be quite tight, a relaxing incision should be made in the conjunctiva posteriorly, the size depending on the requirements for relaxation. The posterior edge of the conjunctiva can be sutured to the sclera and the wound posterior to the incision left to re-epithelialize. A relaxing incision may decrease the possibility of ptosis or diplopia, two of the complications that can occur with conjunctival advancement.

Conjunctival Pedicle Flap. For moderate to large blebs, the use of a rotated conjunctival pedicle flap maintains a blood supply, allows a naturally curved limbal junction and minimizes ptosis.

Measure the bleb to determine the required flap width, and outline the flap with light cautery [Fig. 23.1(A) and (B)].

Figure 23.4 (See color insert) Edges trimmed as necessary and anchored to the limbus region.

necessary and anchored to the limbus region, using a continuous nylon suture, which prevents the conjunctiva from retracting. The posterior edge of the graft is tacked with Vicryl suture to the anterior edge of Tenon’s capsule, which epithelializes rapidly [Fig. 23.4(A) and (B)].

Autologous Conjunctival Graft. We prefer this technique especially when the bleb is of larger size or the surrounding conjunctiva is immobile and/or inflammed.

1.Measure the bleb size both anterior/posterior and side-to-side. Remember if the

bleb is high domed, add an additional 2 3 mm to the measurements all round in both diameters.

2.Using a pen, mark out the size of donor conjunctiva ideally in the inferonasal quadrant (keep the inferotemporal quadrant for possible later seton insertion).

3.Inject local anesthetic subconjunctivally into the delineated area and carefully dissect out the donor conjunctiva and tenons. Utilize enough conjunctiva to cover the leaking bleb without tension (or the conjunctiva will retract and expose the leak) including limbal conjunctiva if required. At all costs, avoid cutting underlying muscles. Place the donor conjunctiva epithelial side up (the pen mark side up) on a wet piece of cotton gauze. Keep the donor conjunctiva wet, while preparing its bed.

4.De-epithelialize the bleb with alcohol. Dissect around the bleb as close to the bleb as possible. Undermine the recipient conjunctiva, thus mobilizing it to receive the donor conjunctiva without tension.

5.Place the donor conjunctiva over the de-epithelialized bleb. Use four 10/0 nylon sutures to fixate the edge of the donor to the edge of the recipient conjunctiva. We then fixate the donor to limbus and recipient conjunctiva with a running 10/0 nylon suture.

6.Do not attempt to repair the inferior defect. It will heal over in a few days without problem.

7.Postoperatively, we recommend an eye patch and shield for 3 days with antibiotic steroid combination (e.g., Tobradex QID) for 4 days followed by steroid use for a further 3 6 weeks depending on reaction to the donor. The sutures can be removed after 4 6 weeks if required.

8.If the bleb continues to leak despite donor conjunctival grafting or conjunctival advancement, we then recommend closing the scleral trabeculectomy site with a donor scleral patch graft followed by repeat trabeculectomy at a distant site if necessary.

The table below summarizes the different techniques, the year of the study, the number of patients, and the success rate. Most authors define success as pressure .6 and ,21 mmHg with resolution of the leak and no need for subsequent glaucoma surgery. It should be noted that amniotic membrane transplantation is not included in the table. A large review by Budenz (21) reported that amniotic membrane transplant in 15 patients was not as helpful as conjunctival advancement.

% represents percentage of patients requiring glaucoma medication.

4.CONCLUSION

The management of bleb leaks continues to be a challenging problem. Fortunately, attempts at surgical repair can provide very good results that allow preservation of the bleb in most cases. It must be remembered, however, that many of these patients will go on to require glaucoma medications and some will need additional glaucoma surgery. It is always important to evaluate each individual patient to try to weigh the risk of visual

loss from hypotony or endophthalmitis vs. the risk of visual loss due to surgical complications or loss of glaucoma control. Depending on the urgency of the situation, conservative measures can be tried for a short while but fortunately should surgical repair be required, evidence shows that repair allows for safer outcomes much of the time.

REFERENCES

1.Greenfield DS, Liebmann JM, Jee J, Ritch R. Late onset bleb leaks after glaucoma filtering surgery. Arch Ophthalmol 1998; 116(4):443 447.

2.DeBry PW, Perkins TW, Heatley G, Kaufman P, Brumback LC. Incidence of late onset bleb related complications following trabeculectomy with mitomycin. Arch Ophthalmol 2002; 120(3):297 300.

3.Soltau JB, Rothman RF, Budenz DL, Greenfield DS, Feuer W, Liebmann JM, Ritch R. Risk factors for glaucoma filtering bleb infections. Arch Ophthalmol 2000; 118(3):338 342.

4.Leen MM, Moster MR, Katz LJ, Terebuh AK, Schmidt CM, Spaeth GL. Management of overfil

tering and leaking blebs with autologous blood injection. Arch Ophthalmol 1996; 114(5):633 634.

5.Smith MF, Magauran RG, Betchkal J, Doyle JW. Treatment of postfilteration bleb leaks with autologous blood. Ophthalmology 1995; 102(6):868 871.

6.Burnstein A, WuDunn D, Ishii Y, Jonescu Cuypers C, Cantor LB. Autologous blood injection for late onset filtering bleb leak. Am J Ophthalmol 2001; 132(1):36 40.

7.Choudhri SA, Herndon LW, Damji KF, Allingham RR, Shields MB. Efficacy of autologous blood injection for treating overfiltering or leaking blebs after glaucoma surgery. Am J Ophthalmol 1997; 123(4):554 555.

8.Asrani SG, Wilensky JT. Management of bleb leaks after glaucoma filtering surgery. Use of autologous fibrin tissue glue as an alternative. Ophthalmology 1996; 103(2):294 298.

9.Geyer O. Management of large, leaking, and inadvertent filtering blebs with the neodymium:YAG laser. Ophthalmology 1998; 105(6):983 987.

10.Burnstein Al, WuDunn D, Knotts SL, Catoira Y, Cantor LB. Conjunctival advancement versus nonincisional treatment for late onset glaucoma filtering bleb leaks. Ophthalmology 2002; 109(1):71 75.

11.Myers JS, Yang CB, Herndon LW, Allingham RR, Shields MB. Excisional bleb revision to correct overfiltration or leakage. J Glaucoma 2000; 9(2):169 173.

12.van de Geijn, Lemij HG, de Vries J, de Waard PW. Surgical revision of filtration blebs: a follow up study. J Glaucoma 2002; 11(4):300 305.

13.Budenz DL, Chen PP, Weaver YK. Conjunctival advancement for late onset filtering bleb leaks: indications and outcomes. Arch Ophthalmol 1999; 117(8):1014 1019.

14.Catoira Y, Wudunn D, Cantor LB. Revision of dysfunctional filtering blebs by conjunctival advancement with bleb preservation. Am J Ophthalmol 2000; 130(5):574 579.

15.Harris LD, Yang G, Feldman RM, Fellman RL, Starita RJ, Lynn J, Chuang AZ. Autologous conjunctival resurfacing of leaking filtering blebs. Ophthalmology 2000; 107(9):1675 1680.

16.Wilson MR, Kotas Neumann R. Free conjunctival patch for repair of persistent late bleb leak. Am J Ophthalmol 1994; 117(5):569 574.

17.Schnyder CC, Shaarawy T, Ravinet E, Achache F, Uffer S, Mermoud A. Free conjunctival autologous graft for bleb repair and bleb reduction after trabeculectomy and nonpenetrating filtering surgery. J Glaucoma 2002; 11(1):10 16.

18.Wadhwani RA, Bellows AR, Hutchinson BT. Surgical repair of leaking filtering blebs. Ophthalmology 2000; 107(9):1681 1687.

19.LaBorwit SE, Quigley HA, Jampel HD. Bleb reduction and bleb repair after trabeculectomy. Ophthalmology 2000; 107(4):712 718.

20.Kosmin AS, Wishart PK. A full thickness scleral graft for the surgical management of a late filtration bleb leak. Ophthalmic Surg Lasers 1997; 28(6):461 468.

21.Budenz DL, Barton K, Tseng SC. Amniotic membrane transplantation for repair of leaking glaucoma filtering blebs. Am J Ophthalmol 2000; 130(5):580 588.

Figure 24.2 Elevated bleb close to the disc margin. The tear film at the limbal margin of the bleb is unstable and will predispose to the formation of dellen.

2.3.The Elevated Bleb

In general, elevated blebs are thin walled and cystic in appearance and usually arise several months after filtration surgery. They tend to have a well-demarcated boundary and are relatively avascular. In contrast, Tenon’s cysts which occur in the early postoperative phase usually have diffuse with boundaries and are well vascularized. The management of blebs with Tenon’s cysts is dealt with in more detail in Chapter 6.

Elevated cystic blebs (Fig. 24.2) cause discomfort, either as a direct result of the configuration of the bleb or because of surrounding effects on the ocular surface. The commonest symptom is a foreign body sensation which is localized to the site of the bleb. In many cases, this may be associated with moderate epiphora and slight reduction in vision.

Large elevated blebs can cause difficulties with lid closure (Fig. 24.3). Patients may have to resort to placing the upper lid manually over the bleb so that full lid closure can be achieved. In some cases, a large bleb can also prevent lid elevation, resulting in a mechanical ptosis (Fig. 24.4). If untreated, this can cause long-term damage to the levator aponeurosis complex in which the ptosis persists following management of the bleb dysmorphology. The ptosis can usually be treated by resection of the levator aponeurosis. Large blebs also affect the margin of the upper lid and predispose to the development of

Figure 24.3 Elevated bleb which prevents lid closure. Manual placement of the upper lid was required to ensure that it would pass over the bleb for lid closure to occur.