Background: To evaluate the repeatability and reproducibility of anterior chamber angle measurement obtained by an anterior segment optical coherence tomography.
Methods: 25 normal subjects were invited for anterior chamber angle imaging with the Visante anterior segment optical coherence tomography (OCT) (Carl Zeiss Meditec, Dublin, CA) on one randomly selected eye in 3 separate visits within a week. Each eye was imaged 3 times under room light (light intensity=368lux) and 3 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 analyzed. Intrasession and intersession within subject standard deviation (Sw), precision (1.96 x Sw), coefficient of variation CVw (100 x 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°, 88μm / 4.7°, 5.8% / 4.8% and 0.97 / 0.95 in the light; and 45μm /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°, 155μm /6.8°, 10.0% / 7.0%, 0.91 / 0.89 in the light; and 64μm/ 3.4°, 124μm / 6.6°, 9.9% / 7.8% and 0.95 / 0.92 in the dark.
Conclusions: The Visante anterior segment OCT demonstrated reliable anterior chamber angle measurement in different lighting conditions with good repeatability and reproducibility.
- anterior chamber angle
- anterior segment optical coherence tomography