Ординатура / Офтальмология / Английские материалы / Glaucoma Surgery_Trope_2005

Figure 26.2 Intravenous fluorescein angiogram note choroidal folds with no leakage of dye from the vessels.

with fluorescein angiography include alternating bands of hyper and hypofluorescence due to the choroidal folding, and leakage from the optic nerve but not from retinal capillaries.

4.INCIDENCE

The reported incidence of hypotony maculopathy after filtration surgery (as opposed to simple hypotony) varies, ranging from ,1% to as high as 25% (3,20 24). Major risk factors include younger age, myopia, and the use of intraoperative antimetabolites (20,25). Filtration surgery in younger myopes should always include consideration of the risks of hypotony maculopathy.

5.RISK FACTORS

The risk of hypotony maculopathy is higher with mitomycin C than with 5-fluorouracil (23,26), but does not correlate with increased concentrations or exposure times (15,20). Other reported risk factors include high preoperative IOP, younger age, myopic refractive error, preoperative use of oral carbonic anhydrase inhibitors, and possibly a higher rate in white patients than in black (20,21,25,27,28). A large case control study with over 200 cases showed significant risk factors to be young age, male gender, and myopia. The same report showed a protective effect from diabetes and the presence of choroidal effusions (19), whereas a smaller case control study suggested that patients younger than 60 years of age were more likely to develop maculopathy with hypotony than were patients over 60 (6).

6.MANAGEMENT

The best management is prevention. Surgeons should be careful to produce tight scleral closure, especially in young myopes in whom antimetabolites have been used. Meticulous

closure of the conjunctival flap is also important. If hypotony maculopathy is diagnosed, therapy is best aimed at the underlying cause of the hypotony. Simple treatment of the IOP, such as with repeated filling of the anterior chamber with viscoelastics, is rarely sufficient (2). Hyung and Jung (24) recommend a stepwise approach, from medical management to blood injection to bleb and flap revision, finding a 79% success rate in 24 treated eyes with this approach. These more advanced management options are discussed subsequently.

1.The bleb should be repaired if leaking, or revised if overfiltering (29). Repair of an overfiltering bleb has been shown to improve IOP in a good proportion of patients, in the range of 86% (30). The actual surgical techniques for management of the leaking or overfiltering bleb are covered in other chapters.

2.Potential treatments other than full surgical repair have also been tried and successfully performed. Several authors have reported the use of subconjunctival intrableb or peribleb autologous blood injection (31). The usual technique is to withdraw 0.1 0.3 mL of whole blood from the antecubital vein, and slowly inject it either into the bleb itself or around it. The technique involves inserting the needle under the conjunctiva starting at least 3 mm from the edge of the bleb. A sterile 30-gage needle is advanced under the conjunctiva into the center of the bleb area and the bleb is filled with blood. Autologous blood can also be used with compression sutures over the bleb (32,33). A risk with introducing a large subconjunctival hemorrhage into the bleb site is the tracking of blood through the scleral flap and surgical ostomy into the anterior chamber (34,35). Corneal blood staining, hyphema, and vitreous hemorrhage have all been reported with the use of autologous blood injections (36,37). Injecting behind and around the bleb may decrease the risk of intracameral extension, and may be equally effective at introducing fibroblasts into the area (33,38).

3.Variations of the technique include use of a Nd:YAG laser to induce subconjunctival bleeding by puncturing a subconjunctival blood vessel, and a case report included the introduction of intracameral viscoelastic prior to the laser, with resolution of hypotony (34,35). The laser settings reported were

1.8 mJ per pulse, and two pulses per burst. Success rates, in small reported series, are 50 60% (38). Care must be taken to avoid rupturing a thin walled bleb, and, although intracameral viscoelastic injection prior to the laser application can increase the resistance to blood flow into the eye, it can also increase the IOP and the risk of corneal blood staining if blood enters.

4.Cryotherapy, and both YAG and argon laser energy have been used to incite a bleb reaction and decrease filtration, rather than to induce bleeding. A reported technique described topical anesthetic and rose bengal instillation over the

bleb after light epithelial debridement. The laser settings used were a 100 mm spot size for 0.3 s duration at a power of 600 800 mW over two sessions to shrink the bleb. This technique successfully raised the IOP from zero to10 mmHg in a case report (39).

5.The technique for cryotherapy to the bleb involves five applications of the cryo

probe at 808C for 25 s each (3). Typically, 5 6 cryo treatments are applied under topical anesthesia to the bleb periphery until the patient “feels” the treatment about 10 15 s at 808C. We have successfully used this technique on a number of cases. For all of these techniques, complications include undertreatment, with lack of effect; over-treatment, with fibrosis and subsequent inadequate filtration; and inadvertent bleb perforation.

6.Other surgical options include cataract extraction (40). A report has shown that clear corneal phacoemulsification surgery resulted in increased IOP and increased vision in seven of nine eyes with hypotony maculopathy (41).

7.However, before cataract surgery is considered we primarily recommend exploration and suture of the scleral flap after identifying the leaking area. The conjunctiva should be closed in two layers. If the scleral flap is too thin or friable for suture closure, then a donor scleral flap should be sutured over the thin leaking area using 10-0 nylon. If a scleral patch is used, a pressure spike with pain should be expected after a few days. This should initially be dealt with using medical therapy, but repeat filtration surgery without antifibroblastic therapy may be needed if the pressure returns to a level above target for that patient. We have on occasion sealed a friable scleral flap with donor sclera followed by immediate trabeculectomy without mitomycin C at a distant site to prevent the expected pressure spike.

7.PROGNOSIS

Visual loss may be irreversible, but outcomes with a return of vision following resolution of the hypotony as late as 6 months, or even 7 years have been reported (34,42). As a rule, however, treatment of hypotony within a few weeks, is recommended to either prevent the development of maculopathy, or allow its resolution with an excellent chance of retaining or restoring vision (24,27,43).

ACKNOWLEDGMENT

We would like to acknowledge the generosity of Dr. Peter Kertes in supplying the color and fluorescein photographs used in this chapter.

REFERENCES

1.Bardak Y, Cuypers MH, Tilanus MA, Eggink CA. Ocular hypotony after laser suture lysis following trabeculectomy with mitomycin C. Int Ophthalmol 1997; 21:325 330.

2.Pederson JE. Ocular hypotony. In: Ritch R, Shields MB, Krupin T, eds. The Glaucomas. 2nd ed. St Louis: Mosby, 1996; Chap. 18.

3.Costa VP, Wilson RP, Moster MR et al. Hypotony maculopathy following the use of topical mitomycin C in glaucoma filtration surgery. Ophthalmic Surg 1993; 24:389 394.

4.Kee C, Kaufman PL. Profound long term hypotony without maculopathy after trabeculectomy with antimetabolite. Acta Ophthalmol (Copenh) 1994; 72:388 390.

5.Gass JD. Hypotony maculopathy. In: Bellows JC, ed. Contemporary Ophthalmology, Honor ing Sir Stewart Duke Elder. Baltimore: Williams & Wilkins, 1972.

6.Stamper RL, McMenemy MG, Lieberman MF. Hypotonous maculopathy after trabeculectomy with subconjunctival 5 fluorouracil. Am J Ophthalmol 1992; 114:544 553.

7.Zacharia PT, Deppermann SR, Schuman JS. Ocular hypotony after trabeculectomy with mitomycin C. Am J Ophthalmol 1993; 116:314 326.

8.Nuyts RM, Felten PC, Pels E et al. Histopathologic effects of mitomycin C after trabeculectomy in human glaucomatous eyes with persistent hypotony. Am J Ophthalmol 1994; 118:225 237.

9.Shaikh A, Ahmado A, James B. Severe cough: a cause of late bleb leak. J Glaucoma 2003; 12:181 183.

10.Keller C, To K. Bleb leak with hypotony after laser suture lysis and trabeculectomy with mitomycin C. Arch Ophthalmol 1993; 111:427 428.

11.Kennedy CJ, Roden DM, McAllister IL. Suprachoroidal effusion following argon laser trabe culoplasty. Aust N Z J Ophthalmol 1996; 24:279 282.

12.Morinelli EN, Sidoti PA, Heuer DK et al. Laser suture lysis after mitomycin C trabeculectomy. Ophthalmology 1996; 103:306 314.

13.Savage JA, Condon GP, Lytle RA, Simmons RJ. Laser suture lysis after trabeculectomy. Ophthalmology 1988; 95:1631 1638.

14.Schwartz AL, Weiss HS. Bleb leak with hypotony after laser suture lysis and trabeculectomy with mitomycin C. Arch Ophthalmol 1992; 110:1049.

15.Shields MB, Scroggs MW, Sloop CM, Simmons RB. Clinical and histopathologic observations concerning hypotony after trabeculectomy with adjunctive mitomycin C. Am J Ophthalmol 1993; 116:673 683.

16.Geijssen HC, Greve EL. Mitomycine, suterelysis and hypotony. Int Ophthalmol 1992; 16:371 374.

17. Macken P, Buys Y, Trope G. Glaucoma laser suture lysis. Br J Ophthalmol 1996; 80:398 401.

18.Faingold D, Francis CJ, Buys YM. Hypotony maculopathy and papilledema after trabeculec tomy in a patient with pseudotumor cerebri. J Glaucoma 2003; 12:374 378.

19.Fannin LA, Schiffman JC, Budenz D. Risk factors for hypotony maculopathy. Ophthalmology 2003; 110:1185 1191.

20.Bindlish R, Condon GP, Schlosser JD et al. Efficacy and safety of mitomycin C in primary trabeculectomy: five year follow up. Ophthalmology 2002; 109:1336 1341.

21.Costa VP, Moster MR, Wilson RP et al. Effects of topical mitomycin C on primary trabeculec tomies and combined procedures. Br J Ophthalmol 1993; 77:693 697.

22.Perkins TW, Gangnon R, Ladd W et al. Trabeculectomy with mitomycin C: intermediate term results. J Glaucoma 1998; 7:230 236.

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

24.Hyung SM, Jung MS. Management of hypotony after trabeculectomy with mitomycin C. Korean J Ophthalmol 2003; 17:114 121.

25.Hong C, Hyung SM, Song KY et al. Effects of topical mitomycin C on glaucoma filtration surgery. Korean J Ophthalmol 1993; 7:1 10.

26.Kitazawa Y, Suemori Matsushita H, Yamamoto T, Kawase K. Low dose and high dose mito mycin trabeculectomy as an initial surgery in primary open angle glaucoma. Ophthalmology 1993; 100:1624 1628.

27. Stamper R. Bilateral chronic hypotony following trabeculectomy with mitomycin C. J Glaucoma 2001; 10:325 328.

28.Suner IJ, Greenfield DS, Miller MP et al. Hypotony maculopathy after filtering surgery with mitomycin C. Incidence and treatment. Ophthalmology 1997; 104:207 214.

29.Schwartz GF, Robin AL, Wilson RP et al. Resuturing the scleral flap leads to resolution of hypotony maculopathy. J Glaucoma 1996; 5:246 251.

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

31.Wise JB. Treatment of chronic postfiltration hypotony by intrableb injection of autologous blood. Arch Ophthalmol 1993; 111:827 830.

32.Haynes WL, Alward WL. Combination of autologous blood injection and bleb compression sutures to treat hypotony maculopathy. J Glaucoma 1999; 8:384 387.

33.Okada K, Tsukamoto H, Masumoto M et al. Autologous blood injection for marked overfiltration early after trabeculectomy with mitomycin C. Acta Ophthalmol Scand 2001; 79:305 308.

34.Ascaso FJ, Loras E, Cristobal JA. Combination of Nd:Yag laser induced subconjunctival bleeding and intracameral viscoelastic injection to treat hypotony maculopathy. Ophthalmic Surg Lasers 2002; 33:504 507.

35.Bettin P, Carassa RG, Fiori M, Brancato R. Treatment of hyperfiltering blebs with Nd:YAG laser induced subconjunctival bleeding. J Glaucoma 1999; 8:380 383.

36.Ayyala RS, Urban RC Jr, Krishnamurthy MS, Mendelblatt DJ. Corneal blood staining follow ing autologous blood injection for hypotony maculopathy. Ophthalmic Surg Lasers 1997; 28:866 868.

37.Flynn WJ, Rosen WJ, Campbell DG. Delayed hyphema and intravitreal blood following intra bleb autologous blood injection after trabeculectomy. Am J Ophthalmol 1997; 124:115 116.

38.Leen MM, Moster MR, Katz LJ et al. Management of overfiltering and leaking blebs with autologous blood injection. Arch Ophthalmol 1995; 113:1050 1055.

39.Akova YA, Dursun D, Aydin P et al. Management of hypotony maculopathy and a large filter ing bleb after trabeculectomy with mitomycin C: success with argon laser therapy. Ophthalmic Surg Lasers 2000; 31:491 494.

40.Sibayan SAB, Igarashi S, Kasahara N et al. Cataract extraction as a means of treating postfil tration hypotony maculopathy. Ophthalmic Surg Lasers 1997; 28:241 243.

41.Doyle JW, Smith MF. Effect of phacoemulsification surgery on hypotony following trabecu lectomy surgery. Arch Ophthalmol 2000; 118:763 765.

42.Delagdo MF, Daniels S, Pascal S, Dickens CJ. Hypotony maculopathy: Improvement of visual acuity after 7 years. Am J Ophthalmol 2001; 132:931 933.

43.Schnyder CC, Shaarawy T, Ravinet E et al. Free conjunctival autologous graft for bleb repair and bleb reduction after trabeculectomy and nonpenetrating filtering surgery. J Glaucoma 2002; 11:10 16.

Bleb-associated endophthalmitis by definition refers to an infected bleb with associated intraocular infection. This is characterized by a hypopyon, a vitritis, and/or a positive vitreous culture. Bleb-associated endophthalmitis occurs early or late in the postoperative period. Acute endophthalmitis usually occurs within the first 2 weeks following surgery. Late-onset bleb-associated endophthalmitis, typically occurs months to years postoperatively.

2.RISK FACTORS

The major risk factor for infection is a leaking bleb (2). Other risk factors include chronic bacterial blepharitis or conjunctivitis, keratitis sicca, the use of contaminated eye drops or bottle tips, and contact lens wear (2). In addition, inferiorily placed trabeculectomies carry an increased risk of bleb-associated endophthalmitis compared with superior blebs (3). Inferior blebs are poorly protected by the lower lid, and may be exposed to chronic mechanical irritation by the lid margin during blinking. This results in a more friable conjunctival epithelium over the bleb. In addition, these blebs are exposed to both the bacteria-rich inferior tear film meniscus and the bacterial flora of lower eyelid margin.

Several authors have reported an increased risk of blebitis and bleb-associated endophthalmitis after filtering surgery with mitomycin C and 5-fluorouracil (3 6). This is attributed to the fact that these blebs are more likely to be thin, avascular, and cystic. Several histopathological studies of blebs after trabeculectomy with mitomycin have demonstrated irregularities in the conjunctival epithelium, breaks in the basement membrane, conjunctival and subconjunctival hypocellularity (7 10). Each of these findings predispose towards a late-onset bleb leak. Trabeculectomies combined with adjunctive 5-fluorouracil have a higher incidence of bleb leaks, and trabeculectomies performed with mitomycin have an even higher rate of bleb leaks (11,12). Soltau et al. (13), reported that eyes with bleb-related infections are 26 times more likely to have a concomitant bleb leak, than eyes without bleb-related infections.

Patients undergoing combined cataract surgery and trabeculectomy are less likely to develop bleb-related infections compared with patients who have a trabeculectomy procedure alone (14). This is due to the fact that the blebs in eyes following combined procedures tend to be thicker and therefore less susceptible to bleb leaks with secondary infection.

The intermittent or chronic use of topical antibiotics, beyond the early postoperative period, is also associated with an increased risk of bleb-related infections (14). It is possible that the prolonged use of topical antibiotics may select for more virulent and antibiotic resistant bacteria.

Other risk factors implicated as having a causal role in bleb-related infections include nasolacrimal duct obstruction, releasable sutures, dementia (poor hygiene), poor follow-up, the use of systemic corticosteroids, juvenile glaucoma, the use of epinephrine drops, bleb-needling, bleb remodeling, and trauma (14 16). Early postoperative complications such as early wound leak, flat anterior chamber (AC), and suprachoroidal hemorrhage are associated with an increased incidence of late-onset bleb-related infections (14).

3.INCIDENCE

The incidence of acuteand late-onset bleb-related infections ranges from 0.4% to 6.9%. In contrast, the reported incidence of acute postoperative endophthalmitis after other types

of intraocular surgery is significantly lower at 0.05% (17,18). Several studies have reported that the incidence of bleb-related infections ranges from 1.1% to 1.6% per year and it is postulated that this figure is increasing because of the increased use of adjuvant antifibrotic agents (3,4,12).

4.DIAGNOSIS

It is very important to differentiate between blebitis, which is considered a “localized bleb infection” without involvement of intraocular contents, and the more serious blebassociated endophthalmitis. The treatment and prognosis for these two entities are different.

4.1.Blebitis

Symptoms associated with blebitis include tearing, photophobia, ocular injection, foreign body sensation, and discharge. Patients present with a mucopurulent discharge and severe ciliary and conjunctival hyperemia. This is mostly localized around the infiltrated opalescent filtering bleb that has a milky-white appearance with loss of clarity (Fig. 27.1). Seidel test is often positive. Some patients with leaking blebs may have hypotony and even a shallow or flat AC. High intraocular pressure is also possible due to obstruction of the sclerostomy site with purulent debris.

4.2.Bleb-Associated Endophthalmitis

Patients with bleb-associated endophthalmitis have a rapidly progressive deterioration in their clinical presentation, characterized by worsening pain, discharge, reduction of vision, marked hyperemia, and increasing AC reaction with or without a hypopyon. A positive Seidel test is common. In contrast to patients with blebitis, patients with bleb-associated endophthalmitis have vitreous involvement which may range from just a few vitreous cells detectable on slit lamp examination with a dilated pupil to frank intravitreal abscess formation obscuring visualization of the fundus. In cases of poor posterior pole visibility B-scan ultrasonography is a useful method to detect vitreous involvement.

Figure 27.1 Avascular infiltrated opalescent filtering bleb surrounded by congested conjunctival vessels.

5.MICROORGANISMS

Early-onset bleb-related infections (blebitis and bleb-associated endophthalmitis) are reported to have a similar spectrum of causative bacterial organisms as that of acuteonset endophthalmitis postcataract surgery. In blebitis (early and late), the most commonly cultured organisms are Staphylococcus epidermidis and Propriobacterium acnes, which are considered to be part of the normal flora of the ocular surface (1,19 21). Other studies have reported an increased association between blebitis and Staph. aureus (22).

The diagnosis of blebitis should be established as soon as possible based on clinical presentation. The use of conjunctival cultures should be obtained if possible, before instituting appropriate antibiotic treatment (23). However, a positive bleb culture does not always differentiate a bleb infection from normal conjunctival colonization. Intraocular cultures from patients with blebitis are limited because these patients typically have a good response to topical and systemic antibiotic treatment, thereby obviating the need for further invasive diagnostic procedures.

In early-onset bleb-associated endophthalmitis, the most commonly isolated organisms are Staph. epidermidis and P. acnes (1). Unlike early and late blebitis as well as early bleb-associated endophthalmitis, the most common organisms isolated from late-onset bleb-associated endophthalmitis, are Streptococcus species (accounting for 41 57% of culture positive cases) and gram-negative organisms (23 31%) such as Hemophilus influenzae, followed by staphylococcal species (1,4,19,24 27).

To explain this discrepancy in causative organisms between earlyand late-onset bleb-associated endophthalmitis, it has been suggested that the perioperative introduction of normal host ocular flora is responsible for early-onset bleb-associated endophthalmitis. Late bleb-associated endophthalmitis is likely caused by transconjunctival migration of transiently present aggressive bacteria from the ocular surface. They gain access to the intraocular contents through thin walled and leaking blebs (1,24). It has also been suggested that patterns of causative organisms have changed over the past decade, with staphylococcal infections becoming more common (28). This may be due to the increased use of intraoperative mitomycin C that has led to more bleb leaks with infection caused by organisms that do not require transconjunctival migration.

The relationship between conjunctival and intraocular cultures in late-onset blebassociated endophthalmitis is equivocal. Mandelbaum et al. reported that in the majority of cases (72%), the organism cultured from the intraocular contents (aqueous and vitreous) was different from the organism isolated from the ocular surface. They reported that direct swabbing of the bleb does not improve the ability to identify the intraocular organism. They recommended that cultures obtained from the bleb surface not to be used as a guide for the selection of appropriate antibiotic therapy in bleb-associated endophthalmitis (24). Several studies have shown that cultures obtained from the AC in patients with blebitis and bleb-associated endophthalmitis are often negative, both in aphakic eyes and in eyes that have undergone posterior capsulotomy (24,25). If the vitreous is clinically not involved, then vitreous cultures are not required. However, when the vitreous is involved with cells and/or infiltrates, it is the intraocular site with the highest yield for microbial isolation.

6.PROGNOSIS

Early bleb-related infections tend to have a favorable prognosis with patients retaining relatively good visual acuity. This is attributable to the less virulent nature of these