frequently isolate different organisms than cultures from intraocular aspirates.84 Therefore, although a culture of the conjunctivae should be performed, it is not necessarily an accurate indicator of the intraocular pathogen. If there is marked anterior chamber reaction, an anterior chamber tap must be considered prior to starting antibiotics.46 If the vitreous is involved, a vitreous tap and/or vitrectomy with injection of intraocular antibiotics should be performed.46 Gram stains, cultures, and sensitivities should be performed on all specimens.

Management of blebitis and bleb-associated endophthalmitis depends on the extent of ocular involvement. Azuara-Blanco and Katz46 have outlined a logical approach for the treatment of blebitis and bleb-associated endophthalmitis. If the bleb is involved with minimal AC reaction, then topical administration (q30m to q1h) of a fluoroquinolone antibiotic may resolve the infection. Bacitracin ointment, which has good gram-positive coverage, may be added at bedtime. If there is significant reaction in the anterior segment but not the posterior segment, it is advisable to treat with fortified antibiotics. Fortified cefazolin (50 mg/mL) may be used as a single agent because it covers most of the organisms found in bleb-associated endophthalmitis. It may be preferable to use topical fortified vancomycin (25 mg/mL) and amikacin (50 mg/mL) or tobramycin (14 mg/ mL) to cover both gram-positive and gram-negative organisms. Topical steroids may be started when the infection appears to be controlled, usually after 24 to 48 hours of antibiotics. Steroids may help to prevent scarring of the filtering bleb, allowing it to continue functioning after resolution of the infection. The role of periocular and systemic antibiotics in the treatment of bleb-associated endophthalmitis has not been evaluated, but ofloxacin (400 mg po b.i.d.) may be beneficial because of its high penetration into the vitreous. If the vitreous is involved, intravitreal antibiotics should be given after a core vitrectomy for culture has been performed. The use of fortified antibiotic drops (same as intravitreal injections) and oral ofloxacin (400 po b.i.d.) is also recommended.46

The question as to whether prophylactic topical antibiotic usage is beneficial in preventing blebitis and bleb-related endophthalmitis has not been answered. Most ophthalmologists do not prescribe routine prophylactic topical antibiotics, but it seems logical in patients who may have an increased risk for infection (inferiorly located blebs, bleb leaks, patients with chronic blepharitis).46

CONCLUSION

This chapter has examined predisposing factors to complications as well as the intraoperative and post-

operative complications of phacotrabeculectomy and the NPTSs (deep sclerectomy and viscocanalostomy).

When comparing the three procedures, trabeculectomy with antimetabolite usage seems to have the greatest risk for postoperative complications. Viscocanalostomy, although the most difficult of the three procedures to perform, emerges as the safest procedure. This is because a bleb rarely forms. If one does form, it is usually not the ischemic thin-walled bleb caused by antimetabolites. Deep sclerectomy appears to lie between trabeculectomy and viscocanalostomy in terms of complication potential. A bleb is produced in deep sclerectomy surgery, and therefore a long-term risk of endophthalmitis exists.

Direct comparison of the postoperative IOP results of the three procedures is difficult because no study involving all three procedures in the same patient population has been performed. Mermoud et al19 compared deep sclerectomy with the Aquaflow collagen sponge to trabeculectomy (without antimetabolites at the time of surgery) and found a 48.2% lowering of IOP at 12 months in the deep sclerectomy group (13.8 3.7 versus 26.7 7.3 mm Hg preoperatively; p <.0001) compared to 53.2% lowering in the trabeculectomy group (11.9 4.4 versus 25.4 7.3 mm Hg preoperatively; p <.0001). The difference between groups was not statistically significant at 12 months.

Mermoud and colleagues91 also reported a study in which deep sclerectomy without Aquaflow implant was compared with deep sclerectomy with Aquaflow implant. At 18 months postsurgery, the mean IOP reduction was 48% (14.0 3.7 versus 26.9 8.8 mm Hg preoperatively) in the deep sclerectomy with Aquaflow implant group, compared with the mean IOP reduction of 31% (17.8 8.3 versus 25.8 8.5 mm Hg preoperatively) in the deep sclerectomy without Aquaflow group. This difference was not statistically significant.

Stegman et al22 has achieved impressive results with viscocanalostomy in their patient population of black Africans, a population that has fared poorly with trabeculectomy surgery. They report a mean IOP reduction of 64% (16.85 8.0 mm Hg postoperatively without additional medical therapy, versus 47.4 13 mm Hg preoperatively on no medical therapy).

The exact mechanism by which the viscocanalostomy works is unclear. Blanching of the collector system vessels when injecting BSS into the ostia of Schlemm’s canal supports the concept that this is a major pathway for aqueous outflow. The fact that some patients get small bleb formation even with a tightly sutured superficial flap indicates that some aqueous may drain transsclerally through the superficial flap. It is difficult to achieve single-digit IOPs with viscocanalostomy, and therefore at this time if a patient needs such a low IOP to protect residual optic

nerve fibers, a trabeculectomy with mitomycin-C may be a better choice of operation. If a patient has a relatively healthy optic nerve and needs to have a postoperative IOP in the middle to upper teens for glaucoma control, then viscocanalostomy may be the procedure of choice. Stegman has achieved singledigit IOPs in several patients after viscocanalostomy and he attributes this to the close proximity of the scleral lake to a large collector channel.26 As more is learned about the subtle nuances of this procedure, titration of postoperative IOP may be possible. I believe that viscocanalostomy will become an integral part of the glaucoma surgeon’s armamentarium.

ACKNOWLEDGMENTS

I would like to thank Dr. Robert Stegman and other pioneers of nonpenetrating trabecular surgery for revitalizing glaucoma surgery with less invasive surgery that causes fewer complications than trabeculectomy surgery.

REFERENCES

1.Abramowicz M, ed. Vitamin supplements. The Medical Letter 1998;40:75.

2.Del Toro M, Start WJ, Bell WR. Aspirin intake and bleeding during cataract surgery [letter]. J Cataract Refract Surg 1999;25:301–302.

3.Majerus PW, Broze GJ Jr, Miletich JP, et al. Anticoagulant, thrombolytic, and antiplatelet drugs. In: Goodman, Gilman, eds. The Pharmacological Basis of Therapeutics. 9th ed. New York: McGraw-Hill; 1996:1347– 1348.

4.Abramowicz M, ed. Drugs for pain. The Medical Letter 1998;40:79–80.

5.Abramowicz M, ed. Rofecoxib for osteoarthritis and pain. The Medical Letter 1999;41:59–61.

6.Abramowicz M, ed. Clopidogrel for reduction of atherosclerotic events. The Medical Letter 1998;40:59–60.

7.Abramowicz M, ed. Ticlopidine for prevention of stroke. The Medical Letter 1992;34:65–66.

8.Baudouin C, Pisella PJ, Fillacier K, et al. Ocular surface inflammatory changes induced by topical antiglaucoma drugs: human and animal studies. Ophthalmology 1999;106:556–563.

9.Lavin MJ, Wormald RPL, Migdal CS, et al. The influence of prior therapy on the success of trabeculectomy. Arch Ophthalmol 1990;108:1543–1548.

10.Broadway DC, Grierson I, O’Brien C, et al. Adverse effects of topical antiglaucoma medications. I. The conjunctival cell profile. II. The outcome of filtration surgery. Arch Ophthalmol 1994;112:1437–1454.

11.Herreras JM, Pastor JC, Calonge M, et al. Ocular surface alteration after long-term treatment with an antiglaucomatous drug. Ophthalmology 1998;99:1082– 1088.

12.Brandt JD, Wittpenn JR, Katz LJ, et al. Conjunctival impression cytology in patients with glaucoma using long-term topical medication. Am J Ophthalmol 1991; 112:297–301.

13.Schwab IR, Linberg JV, Gioia VM, et al. Foreshortening of the inferior conjunctival fornix associated with chronic glaucoma medications. Ophthalmology 1992; 99:197–202.

14.Cairns JE. Trabeculectomy: preliminary report of a new method. Am J Ophthalmol 1968;66:673–679.

15.Watson PG, Jakeman C, Ozturk M, et al. The complications of trabeculectomy (a 20 year follow-up). Eye 1990;4:425–438.

16.Stewart WC, Shields MB. Management of anterior chamber depth after trabeculectomy. Am J Ophthalmol 1988;106:41–44.

17.Ruderman JM, Harbin TS Jr, Campbell DG. Postoperative suprachoroidal hemorrhage following filtration procedures. Arch Ophthalmol 1986;104:201–205.

18.Kozlov VI, Bagrov SN, Anisimova SY, et al. Nonpenetrating deep sclerectomy with collagen. Ophthalmosurgery 1990;3:44–46.

19.Mermoud A, Schnyder CC, Sickenberg M, et al. Comparison of deep sclerectomy with collagen implant and trabeculectomy in open-angle glaucoma. J Cataract Refract Surg 1999;25:323–331.

20.Welsh NH, DeLange J, Wasserman P, et al. The “deroofing” of Schlemm’s canal in patients with openangle glaucoma through placement of a collagen drainage device. Ophthalmic Surg Lasers 1998;29: 216–226.

21.Gianoli F, Schnyder C, Bovey E, et al. Combined surgery for cataract and glaucoma: phacoemulsification and deep sclerectomy compared with phacoemulsification and trabeculectomy. J Cataract Refract Surg 1999;25:340–346.

22.Stegman R, Pienaar A, Miller D. Viscocanalostomy for open-angle glaucoma in black African patients. J Cataract Refract Surg 1999;25:316–322.

23.Tanihara H, Negri A, Akimoto M, et al. Surgical effects of trabeculotomy ab externo on adult eyes with primary open angle glaucoma and pseudoexfoliation syndrome. Arch Ophthalmol 1993;111:1653–1661.

24.Hopkins JJ, Apel A, Trope GE, et al. Early intraocular pressure after phacoemulsification combined with trabeculectomy. Ophthalmic Surg Lasers 1998;29:273– 279.

25.Honjo M, Tanihara H, Inatani M, et al. Phacoemulsification, intraocular lens implantation, and trabeculotomy to treat pseudoexfoliation syndrome. J Cataract Refract Surg 1998;24:781–786.

26.Kearney J, Stegman R, Kratz R, et al. Viscocanalostomy for glaucoma. ASCRS meeting 1999, Seattle. (This course is on videotape.)

27.Stegman R. Viscocanalostomy. Educational film distributed by Alcon and Pharmacia-Upjohn, 1998.

28.Sourdille P, Santiago P, Villain F, et al. Reticulated hyaluronic acid implant in nonperforating trabecular surgery. J Cataract Refract Surg 1999;25:332–339.

29.Cohen JS, Osher RH. Releasable scleral flap suture. Ophthalmol Clin North Am 1988;1:187–197.

30.Wilson RP. Adjuncts to filtering surgery: releasable sutures. In: McAllister JA, Wilson RP, eds. Glaucoma. Stoneham, MA: Butterworths; 1986:243–250.

31.Shin DH. Removable-suture closure of the lamellar scleral flap in trabeculectomy. Ann Ophthalmol 1987; 19:51–53.

32.Johnstone MA, Wellington DP, Ziel CJ. A releasable scleral-flap tamponade suture for guarded filtration surgery. Arch Ophthalmol 1993;111:398–403.

33.Hsu CT, Yarng SS. A modified removable suture in trabeculectomy. Ophthalmic Surg 1993;24:579–584.

34.Maberley D, Apel A, Rootman DS. Releasable “U” suture for trabeculectomy surgery. Ophthalmic Surg 1994;25:251–255.

35.Wilson R. Advanced phaco and combined glaucomaphaco surgery. AAO meeting 1998, New Orleans. (This course is on videotape.)

36.Pederson JE. Hypotony. In: Tasman W, Jaeger EA, eds. Duane’s Clinical Ophthalmology. Vol. 3. Philadelphia, PA: Harper Row; 1–9.

37.Hoskins HD, Migliazzo C. Management of failing filtering blebs with the argon laser. Ophthalmic Surg 1984;15:731–733.

38.Asrani SG, Wilensky JT. Management of bleb leaks after glaucoma filtering surgery: use of autologous fibrin tissue glue as an alternative. Ophthalmology 1996;103:294–298.

39.Sugar HS. Complications, repair and reoperation of antiglaucoma filtering blebs. Am J Ophthalmol 1967; 63:825–833.

40.Ritch R, Shields MB, Krupin T, eds. The Glaucomas. St. Louis: CV Mosby; 1989:282–290.

41.Blok MDW, Kok JHC, van Mil C, et al. Use of the megasoft bandage lens for treatment of complications after trabeculectomy. Am J Ophthalmol 1990;110:264–268.

42.Joiner DW, Liebmann JR, Ritch R. A modification of the use of the glaucoma tamponade shell. Ophthalmic Surg 1989;20:441–442.

43.Hill RA, Aminlari A, Sassani JW, et al. Use of a symblepharon ring for treatment of over-filtration and leaking blebs after glaucoma filtration surgery. Ophthalmic Surg 1990;21:707–710.

44.Weber PA, Baker ND. The use of cyanoacrylate adhesive with a collagen shield in leaking filtering blebs. Ophthalmic Surg 1989;20:284–285.

45.Zalta AH, Wieder RH. Closure of leaking filtering blebs with cyanoacrylate tissue adhesive. Br J Ophthalmol 1991;75:170–173.

46.Azuara-Blanco A, Katz LJ. Major review: dysfunctional filtering blebs. Surv Ophthalmol 1998;43:93–126.

47.Eder G, Numann M, Cerwenka R, et al. Preliminary results of a randomized controlled study on the risk of hepatitis transmission of a two component fibrin sealant. In: Schlag G, Redl H, eds. Fibrin Sealant in Operative Medicine. Vol. 2. New York: SpringerVerlag; 1986:51–59.

48.Wise JB. Treatment of chronic post filtration hypotony by intrableb injection of autologous blood. Arch Ophthalmol 1993;111:827–830.

49.Gehring JR, Ciccarelli EC. Trichloroacetic acid treatment of filtering blebs following cataract extraction. Am J Ophthalmol 1972;74:622–624.

50.Baum M, Weiss HS. Argon laser closure of conjunctival bleb leak [letter]. Arch Ophthalmol 1993;111: 438.

51.Lynch MG, Roesch M, Brown RH. Remodeling filtering blebs with the neodynium:YAG laser. Ophthalmology 1996;103:1700–1705.

52.Cleasby GW, Fung WE, Webster RG. Cryosurgical closure of filtering blebs. Arch Ophthalmol 1972;87: 319–323.

53.Ryams S. Repair of a leaking filtering bleb after trabeculectomy. Glaucoma 1988;10:148–150.

54.O’Connor DJ, Tressler CS, Caprioli J. A surgical method to repair leaking filtering blebs. Ophthalmic Surg 1992;23:336–338.

55.Buxton JN, Lavery KT, Liebmann JM, et al. Reconstruction of filtering blebs with free conjunctival autografts. Ophthalmology 1994;101:635–639.

56.Wilson MR, Kotas-Neumann R. Free conjunctival patch for repair of persistent late bleb leak. Am J Ophthalmol 1994;117:569–574.

57.Melamed S, Ashkenazi I, Belcher DC III, et al. Donor scleral graft patching for persistent filtration bleb leak. Ophthalmic Surg 1991;22:164–165.

58.Soong HK, Meyer RF, Wolter JR. Fistula excision and peripheral grafts in the treatment of persistent limbal wound leaks. Ophthalmology 1988;95:31–36.

59.Ormerod LD, Baerveldt G, Sunalp MA, et al. Management of the hypotonous cyclodialysis cleft. Ophthalmology 1991;98:1384–1393.

60.Simmons RJ, Belcher CD III, Dallow RL. Primary angle-closure glaucoma. In: Tasman W, Jaeger EA, eds. Duane’s Clinical Ophthalmology. Vol. 3. Philadelphia, PA: Harper Row; 28–43.

61.Suguro K, Toris CB, Pederson JE. Uveoscleral outflow following cyclodialysis in the monkey eye using a fluorescent tracer. Invest Ophthalmol Vis Sci 1985;26: 810–813.

62.Karwatowski WAS, Weinreb RN. Imaging of cyclodialysis cleft by ultrasonic biomicroscope. Am J Ophthalmol 1994;117:541–543.

63.Chandler PA, Maumenee AE. A major cause of hypotony. Trans Am Acad Ophthalmol Otolaryngol 1961;65:563–574.

64.Ormerod LD, Baerveldt G, Green RL. Cyclodialysis clefts: natural history, assessment and management. In: Weinstein GW, ed. Open-Angle Glaucoma. New York: Churchill Livingstone; 1986:201–225.

65.Naumann GOH, Volcker HE. Direct cyclopexy for persisting hypotony syndrome due to traumatic cyclodialysis. In: Koch DD, Parke DW, Paton D, eds. Current Management in Ophthalmology. New York: Churchill Livingstone; 1983:143–150.

66.McCannel MA. A retrievable suture idea for anterior uveal problems. Ophthalmic Surg 1976;7:98–103.

67.Barasch K, Galin MA, Baras I. Postcyclodialysis hypotony. Am J Ophthalmol 1969;68:644–645.

68.Maumenee AE, Stark WJ. Management of persistent hypotony after planned or inadvertent cyclodialysis. Am J Ophthalmol 1971;71:320–327.

69.Portney GL, Purcell T. Surgical repair of cyclodialysis induced hypotony. Ophthalmic Surg 1974;5:30–32.

70.Starita RJ, Fellman RL, Spaeth GL, et al. Shortand long-term effects of postoperative corticosteroids on trabeculectomy. Ophthalmology 1985;92:938–946.

71.The Fluorouracil Filtering Surgery Study Group. Fiveyear follow-up of the fluorouracil filtering surgery study. Am J Ophthalmol 1996;121:349–366.

72.Ewing RH, Stamper RL. Needle revision with and without 5-fluorouracil for the treatment of failed filtering blebs. Am J Ophthalmol 1990;110:254–259.

73.Shin DH, Juzych MS, Khatana AK, et al. Needling revision of failed filtering blebs with adjunctive 5- fluorouracil. Ophthalmic Surg 1993;24:242–248.

74.Mardelli PG, Lederer CM, Murray PL, et al. Slit-lamp needle revision of filtering blebs using mitomycin C. Ophthalmology 1996;103:1946–1955.

75.Latina MA, Rankin GA. Internal and transconjunctival neodynium:YAG laser revision of late failing filters. Ophthalmology 1991;98:215–221.

76.Kurata F, Krupin T, Kolker AE. Reopening filtration fistulas with transconjunctival argon laser photocoagulation. Am J Ophthalmol 1984;98:340–343.

77.Van Buskirk EM. Reopening filtration fistulas with the argon laser. Am J Ophthalmol 1982;94:1–3.

78.Oh Y, Katz LJ. Indications and technique for reopening closed filtering blebs using the Nd:YAG laser: a review and case series. Ophthalmic Surg 1993;24:617–622.

79.Swan KC. Reopening of nonfunctioning filters: simplified surgical techniques. Trans Am Acad Ophthalmol Otolaryngol 1975;79:342–348.

80.Schuman JS, Stinson WG, Hutchinson T, et al. Holmium laser sclerectomy: success and complications. Ophthalmology 1993;100:1060–1065.

81.Fink AJ, Boys-Smith JW, Brear R. Management of large filtering blebs with the argon laser. Am J Ophthalmol 1986;101:695–699.

82.Kirk HQ. Cauterization of filtering blebs following cataract extraction. Trans Am Acad Ophthalmol Otolaryngol 1973;77:573–580.

83.Scheie HG, Guehl JJ. Surgical management of overhanging blebs after filtering procedures. Arch Ophthalmol 1979;97:325–326.

84.Wolner B, Liebmann JM, Sassani JW, et al. Late blebassociated endophthalmitis after trabeculectomy with adjunctive 5-fluorouracil. Ophthalmology 1991;98: 1053–1060.

85.Greenfield DS, Suner IJ, Miller MP, et al. Endophthalmitis after filtering surgery with mitomycin. Arch Ophthalmol 1996;114:943–949.

86.Chandler PA, Grant WM. Lectures on Glaucoma. Philadelphia: Lea and Febiger; 1965:402.

87.Bellows AR, McCulley JP. Endophthalmitis in aphakic patients with unplanned filtering blebs wearing contact lenses. Ophthalmology 1981;88:839–843.

88.Tabbara KF. Late infections following filtering procedures. Ann Ophthalmol 1976;8:1228–1231.

89.Rosenberg LF, Siegfried CJ. Endophthalmitis associated with a releasable suture [letter]. Arch Ophthalmol 1996;114:767.

90.Mandelbaum S, Forster RK. Endophthalmitis associated with filtering blebs. Int Ophthalmol Clin 1987;27: 107–111.

91.Sanchez E, Schnyder CC, Sickenberg M, et al. Deep sclerectomy: results with and without collagen implant. Int Ophthalmol 1997;20:157–162.