Bilateral Nonpenetrating Deep Sclerectomy: Difference in Outcomes Between First- and Second-Operated Eyes at 24 Months

Background/Ann: The aim of this study was to assess the difference in outcome between the first-operated and the second-operated eyes after nonpenetrating deep sclerectomy (DS), and to identify potential success predictors for the second eye. Methods: This single-surgeon, retrospective study analyzed the outcomes of all bilateral nonsimultaneous DS with at least 24 months of follow-up. Its main outcome measure was surgical success, defined as unmedicated intraocular pressure (TOP) <= 15 mm Hg associated with a relative reduction >= 20%. Results: In all, 104 eyes of 52 patients who underwent bilateral (standalone or combined) DS, within a mean of 344.3 +/- 526.3 days of each other, were analyzed. Postoperatively, the mean medicated IOP decreased from 20.7 +/- 7.9 (first-operated eyes) and 19.3 +/- 6.6 mm Hg (second-operated eyes) at baseline (P = 0.107) to 13.8 +/- 4.8 [(-33.3%; P < 0.001) first-operated eyes) and 12.7 +/- 3.8 mm Hg [(-34.2%; P < 0.001) second-operated eyes] after 2 years (P = 0 .619) . Postoperative IOP and treatment reduction, respectively, showed fair (r = 0.53) and good (r = 0.71) levels of correlation between fellow eyes. The rates of complete success were comparable between first-operated and second-operated eyes (32.7% and 40.4%, respectively; P = 0.364). At 2 years, among patients whose first-operated eyes were considered a success, 82.4% of surgeries in second eyes were successful (P = 0.001). The odds ratio of a second-operated eye experiencing complete success were 6.32 (P = 0.011) if the first-operated eye experienced complete success. Conclusions: The present study demonstrated a strong association between first-operated and second-operated eyes after DS, in terms of surgical outcomes and IOP reduction. In effect, surgical success in the first-operated eye increases the odds of success in the second eye by 6-fold.