Glaucoma is the second most common cause of blindness and the leading cause of irreversible type of blindness worldwide. Objective: To correlate the angles assessed and categorized by gonioscopy, with the quantified value of angles by the UBM. Method: Participants: Patients having open and closed angles coming to the glaucoma clinic were selected for this study. Grade 0 to Grade 4 were assigned to temporal quadrants of the angles of participants using Shaffer’s classification. Quantification of angles was done by ultrasound biomicroscopy (UBM) using following biometric parameters namely- Angle opening distance at 500µ (AOD 500) from the scleral spur and trabecular meshwork-ciliary process distance (TCPD). Schaffer’s Grade 0,1 and 2 were classified as “narrow angles” and Schaffer’s Grade 3 and 4 as “open angles”. Outcome Measures: Measurements of UBM were calculated and analyzed in relation to measurements of Gonioscopy. Results: Two hundred eyes of 100 patients were analyzed. 96 eyes had “narrow angles” and 104 eyes had “open angles” on gonioscopy. The difference of means calculated by UBM and angle grade estimated by Gonioscopy was significant (p<0.001). The Pearson correlation coefficient was calculated using all UBM parameters and gonioscopy grades which came out significant at the 0.01. Conclusions: The estimated of angle width done by gonioscopy significantly correlated with the angle dimensions those measured by the UBM. Gonioscopy, is thus a reliable method for estimation of the angle width, although it is a subjective test.

Keywords: Glaucoma; Ultrasound Bio-Microscopy; Gonioscopy; Aod; Tcpd.