Evaluation of bleb parameters using ultrasound biomicroscopy and its correlation to intraocular pressure control following trabeculectomy with adjuvant mitomycin C in high-risk glaucoma patients

Abstract

PurposeThe aim of this study was to study the relationship between bleb parameters (height and extent) evaluated using ultrasound biomicroscopy and intraocular pressure (IOP) after subscleral trabeculectomy with mitomycin C in high-risk glaucoma patients.DesignThis was a prospective interventional observational uncontrolled study.Patients and methodsForty eyes of 26 patients with chronic glaucoma with uncontrolled IOP undergoing subscleral trabeculectomy with intraoperative mitomycin C (0.4%) applied for 2 min were followed up for 3 months. An ultrasound biomicroscopy was performed at day 90 to measure the bleb height and extent and a correlation was found between the mean IOP, the percent reduction in IOP, and the bleb height and extent at the same interval.ResultsThe mean bleb height was 1.065 ± 0.991 mm (range 0-3.6 mm) and the mean bleb horizontal extent was 3.214 ± 1.997 mm (range 0-7.9 mm). A moderate positive linear correlation was observed for bleb horizontal extent between 1.8 and 4.97 mm and percentage change in IOP [ΔIOP (%), r = 0.374], and the results were statistically significant (P = 0.054). In terms of bleb height, the correlations with IOP and ΔIOP were found to be weak and of were not statistically significant.ConclusionWe concluded that bleb extent is more representative of bleb function than bleb height and it appears that the percent reduction in IOP is more influenced by the bleb dimensions than the mean IOP.