A Comparative Study of Anterior Segment Optical Coherence Tomography and Gonioscopy in Detection of Narrow, Occludable Angles

Introduction Glaucoma is a group of progressive optic neuropathies and is a leading cause of blindness. Primary angle-closure glaucoma is a global health problem, and if left untreated, it can lead to irreversible vision loss. Anterior segment imaging with optical coherence tomography (AS-OCT) is a rapidly advancing field in ophthalmology. Early detection of narrow, occludable angles using AS-OCT can lead to early and prompt management, resulting in the preservation of vision. Methods We conducted a cross-sectional, outpatient department (OPD)-based study of 212 eyes of patients. Eyes with narrow angles were selected for this study. Eyes identified as having narrow angles on Van Herick (grade ≤2) were confirmed by gonioscopy, and the angles were graded according to the Shaffer gonioscopy grading system. These eyes were further tested using AS-OCT, and the angles, measured in degrees, were graded according to the degrees given in the Shaffer anterior chamber angle grading system. The grades obtained on AS-OCT were compared with those obtained on gonioscopy. The correlation between the narrow angles measured on AS-OCT and those measured on gonioscopy was determined. Results The mean age of the participants was 58.64 years. Of the 212 eyes found to have narrow angles on gonioscopy, 206 eyes (97.2%, 95% CI: 94.0%-99.0%) also had narrow angles on AS-OCT, while six eyes (2.8%, 95% CI: 1.0%-6.1%) were found to have open angles. The chi-square test for association yielded a p-value of <0.001, indicating a statistically significant relationship between AS-OCT and gonioscopy grading. Conclusion This study showed a high correlation between AS-OCT and gonioscopy for grading narrow angles. Gonioscopy remains the gold standard for detecting and managing narrow angles. AS-OCT can be used to identify narrow angles in busy OPDs where these cases can easily be missed. These patients can then be further evaluated with gonioscopy and managed if necessary.