Follow-up of Primary Angle Closure Suspects After Laser Peripheral Iridotomy Using Ultrasound Biomicroscopy and A-Scan Biometry for a Period of 2 Years

Abstract

To determine the morphologic changes in the anterior segment of primary angle closure suspects (PACS) who underwent laser peripheral iridotomy (LPI) for a period of 2 years. PACS (n=82 eyes) of Asian Indian origin who attended the Glaucoma clinic of tertiary eye hospital underwent A-scan biometry and ultrasound biomicroscopy. Anterior chamber depth, anterior chamber angle (ACA), axial length, lens thickness, relative lens position, central corneal thickness, angle opening distance 500, trabecular-ciliary process distance, iris-ciliary process distance, and iris thickness were measured before LPI and after LPI at 1 week, 6 months, 1 year, 1.5 years, and 2 years. Variation in the parameters measured over a period of 2 years was analyzed. Fifteen eyes out of 52 eyes developed into primary angle closure (PAC) with synechial changes. Univariate analysis for the predictive factors of PAC showed no significant association for age, sex, narrow angle, ultrasound biomicroscopy parameters, and vertical cup-disc ratio. When analyzed as continuous variables, decreasing ACA was significant risk factor (95% confidence interval: 0.703, 0.989, P=0.037). Iris-ciliary process distance, ACA, lens thickness, and angle opening distance 500 were the parameters that varied significantly (P<0.05) between "before LPI group" and "after LPI groups." None of the subjects developed increased intraocular pressure after laser iridotomy. In this hospital-based study on the course of PACS subjects after LPI, as many as 28% progressed to PAC. Decreasing ACA was the predictive factor for the progression of PACS to PAC. There was no increase in intraocular pressure, history, or symptoms of acute attack of glaucoma among the study subjects after LPI.