Repeatability and reproducibility of anterior chamber angle measurement with anterior segment optical coherence tomography

Abstract

Aim: To evaluate the repeatability and reproducibility of anterior chamber angle measurement obtained by anterior segment optical coherence tomography. Methods: Twenty-five normal subjects were invited for anterior chamber angle imaging with an anterior segment optical coherence tomography (OCT) on one randomly selected eye in three separate visits within a week. Each eye was imaged three times under room light (light intensity = 368 lux) and three times in the dark during the first visit. In the subsequent visits, each eye was imaged once in the light and once in the dark. The angle opening distance (AOD 500) and the trabecular-iris angle (TIA 500) were measured by a single observer. Only the nasal angle was analysed. Intrasession and intersession within-subject standard deviation (Sw), precision (1.96 × Sw), coefficient of variation (CVw) (100 × Sw/overall mean), and intraclass correlation coefficient (ICC) were calculated to evaluate repeatability and reproducibility. Results: For intrasession repeatability, the Sw, precision, CVw and ICC of AOD/TIA were 45 μm/2.4°, 88 μm/4.7°, 5.8%/4.8% and 0.97/0.95 in the light; and 45 μm/2.1°, 88 μm/4.2°, 7.0%/5.0% and 0.98/0.97 in the dark. For intersession reproducibility, the Sw, precision, CVw and ICC of AOD/TIA were 79 μm/3.5°, 155 μm/6.8°, 10.0%/7.0%, 0.91/0.89 in the light; and 64 μm/3.4°, 124 μm/6.6°, 9.9%/7.8% and 0.95/0.92 in the dark. Conclusions: The anterior segment OCT demonstrated reliable anterior chamber angle measurement in different lighting conditions with good repeatability and reproducibility.