Results of viscocanalostomy for primary open-angle glaucoma

Viscocanalostomy is a nonperforating filtering surgical procedure that may avoid postoperative complications common with standard trabeculectomy. This study was conducted to determine the surgical outcome of this procedure after a postoperative observation period of 12 to 36 months.

Interventional consecutive case series. In a prospective study, a consecutive series of 67 eyes of 67 patients with chronic primary open-angle glaucoma underwent VCS. Excluded were patients with angle closure glaucoma, post-traumatic, uveitic, neovascular, or dysgenetic glaucoma, as well as patients who needed combined cataract-glaucoma procedures. The patients were examined postoperatively on the first day, first week, at 1 month, and then at 3-month intervals through 36 months. At each visit, best-corrected visual acuity, intraocular pressure (IOP), and the appearance of the surgical wound, anterior chamber, and indirect funduscopy were recorded.

Complete success was defined as IOP less than or equal to 20 mm Hg and greater than or equal to 30% IOP reduction without medical or additional surgical treatment compared with the IOP from a preoperative level with maximum tolerated medical therapy; qualified success IOP less than or equal to 20 mm Hg with treatment or an IOP reduction less than 30% from preoperative level with maximum tolerated medical therapy; and qualified failure of an IOP greater than 20 mm Hg with glaucoma medication, but no optic nerve or visual field deterioration and complete failure as an eye requiring further glaucoma surgery or lost visual function. The overall success rate was 88% at 1 year, 90% at 2 years, and 88% at 3 years, with a complete success of 68% at 1 year, 60% at 2 and 59% at 3 years. Four eyes had a perforation of the Descemet membrane, three of those needed peripheral iridectomy; six eyes had a microperforation not needing a peripheral iridectomy. Five eyes presented hyphema. Eight eyes presented deterioration of visual function after surgery: three eyes because of corneal astigmatism, one eye because of cataract, and four presented glaucomatous deterioration of the visual field despite pressures under 20 mm Hg. Four eyes had progressive cataract formation judged as independent from surgery.

VCS provides an overall success rate of 88% and a complete success of 59% 3 years after surgery. The major immediate complication is perforation of the Descemet membrane with a need for peripheral iridectomy. No serious long-term complications were noted in our small series. Visual function remained stable in 55 eyes (82%).