One Month Post-operative Intraocular Pressure Cutoff Predicting the Best Outcome One Year After Trabeculectomy According to Glaucoma Scale Severity

The objective of this study was to identify an early postoperative target intraocular pressure (IOP), which predicts the best long-term control after trabeculectomy with mitomycin C (MMC), based on the glaucoma severity scale. This is a retrospective study of seventy-eight eyes with primary open angle glaucoma in whom a trabeculectomy with MMC was performed between February 2015 and January 2017. Patients were stratified into 3 groups based on the mean defect (MD) and according to the Hodapp-Parrish-Anderson glaucoma grading scale and the European Glaucoma Society 2003 recommendations: group 1 defined as early stage (2 < MD < 6) with a target IOP of < 18 mmHg, group 2 as moderate stage (6 < MD < 12) with a target IOP of < 15 mmHg, and group 3 as severe stage (MD > 12) with a target IOP of < 12 mmHg. The early-stage group presented a 100% success rate; hence, a cutoff IOP is not of value. The cutoff IOPs that had the best sensibility and specificity as given by the receiver operating characteristic curve for the moderate as well as the severe glaucoma stage were 15.5 mmHg and 12.5 mmHg respectively. In the moderate-stage group, the 1-month postoperative IOP ≤ 15.5 mmHg is considered an early cutoff IOP that can predict the trabeculectomy success at 1 year. In the severe stage, the early IOP cutoff that predicts the same success is cut down to 12.5 mmHg. These results are useful for cases in which a slight change in the early postoperative IOP would affect the success of the surgery at 1 year.