Mini-trabeculectomy in eyes with high risk of scarring: midterm follow-up

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PURPOSE: To report on the surgical outcome after at least 1 year of follow-up of mini-trabeculectomy (without scleral radial incisions), which took place in eyes at high risk of postoperative filtering bleb scarring. METHODS: In a prospective, institutional study, mini-trabeculectomy was performed on 26 eyes of 26 consecutive patients aged 40 years and older who had undergone a previous intraocular surgery or had had a post-traumatic recessed anterior chamber angle. The surgical procedure, a modification of the standard trabeculectomy, involved a 3-mm fornix-based conjunctival flap, sclerostomy at 1 mm from the limbus, and a sclerocorneal tunnel without radial incisions. During surgery, 0.4 mg per ml of mitomycin C was applied in the scleral pocket of each eye for 3 minutes. Of the 26 eyes, each of two eyes underwent an intraocular intervention during the first postoperative year and therefore was evaluated only for surgical complications. Another eye underwent inferior mini-trabeculectomy, and three other eyes did not complete 12 months of follow-up. Twenty eyes have completed 12 months or more of follow-up and were included in the midterm calculations of intraocular pressure control. RESULTS: Mean preoperative intraocular pressure (n = 20) was 32.2 ± 9.5 mm Hg with 3.3 ± 0.9 hypotensive medications. After 12 to 37 months (mean, 22.1 ± 6.6) of follow-up, intraocular pressure was 20 mm Hg or less in 18 of 20 eyes (90%) and the mean intraocular pressure was 17.4 ± 2.9 mm Hg (range, 12 to 23) with 1.1 ± 1.2 hypotensive medications (range, 0 to 4). At that time, the filtering bleb was low and fleshy in appearance in 15 eyes (75%). Postoperative complications of the 22 eyes included early postoperative aqueous leakage in one eye (4.5%); cataract extraction took place in one eye and vitrectomy was performed in another eye, 7 and 3 months postoperatively, respectively. The four eyes that were excluded from the study had controlled intraocular pressure at the last examination. CONCLUSION: Mini-trabeculectomy in eyes with high risk of scarring was found efficacious and relatively safe. The relatively small peritomy, the tunnel approach, and the avoidance of radial incisions seem to offer important advantages over the standard trabeculectomy.