Purpose: To assess the pressure-lowering effect and postoperative complications of the viscocanalostomy nonpenetrating filtering procedure.
Setting: A private practice ophthalmic surgery referral center.
Methods: Fifty-six eyes of 41 patients with medically uncontrolled primary open-angle glaucoma had a viscocanalostomy. After a superficial scleral flap was raised, a deep sclerectomy was performed in the scleral bed with deroofing of Schlemm's canal and preparation of a window of Descemet's membrane. The ostia of Schlemm's canal were probed and stretched with sodium hyaluronate 1.4% (Healon GV(R)), and the scleral flap and conjunctiva were sutured. Examinations were performed before surgery and 1, 3, and 14 days and 1, 3, 6, and 12 months postoperatively.
Results: Mean preoperative intraocular pressure (IOP) was 28.1 mm Hg +/- 7.4 (SD) with a mean of 2.4 +/- 0.7 medications. Mean postoperative IOP was 18.6 +/- 7.5 mm Hg with 0 medications at 1 day, 17.4 +/- 5.2 mm Hg with 0.1 medications at 3 days, 19.1 +/- 4. 3 mm Hg with 0.1 medications at 14 days, 19.4 +/- 4.3 mm Hg with 0.4 medications at 1 month, 18.3 +/- 3.6 mm Hg with 0.6 medications at 3 months, 18.0 +/- 2.6 mm Hg with 0.6 medications at 6 months, and 17. 8 +/- 3.8 mm Hg with 0.7 medications at 1 year. After 1 year, IOP was lower than 21 mm Hg without medication in 36% of patients and lower than 21 mm Hg with medication in 79%. Five patients (9%) required a second operation for pressure control. The following postoperative complications occurred: hyphema (2%); postoperative hypotony less than 10 mm Hg (2%); positive Seidel test (17%); further surgery to lower IOP (12%). Cataract surgery was performed in 1 patient (2%) at 4 months. Despite an attempt to close the scleral flap watertight, 26 patients had evidence of subconjunctival drainage (conjunctival microcysts or filtration bleb) at 1 year.
Conclusion: Viscocanalostomy lowered IOP and reduced the need for pressure-controlling medications with a low postoperative complication rate. The high success rates of earlier publications were not reproduced.