Abstract
Purpose::
To evaluate the repeatability and reproducibility of anterior chamber angle measurement with Visante anterior segment OCT.
Methods::
15 normal subjects were invited for anterior chamber angle imaging 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 anterior chamber angle was imaged with the Visante anterior segment OCT (Carl Zeiss Meditec, Dublin, CA) anterior segment single protocol by a single examiner (CC). The angle opening distance (AOD 500) and the trabecular-iris angle (TIA) were measured by the same examiner. Only the nasal angle was analzyed in this study. Intrasession within subject standard deviation (sw), coefficient of variation CVw (100x sw / overall mean) and intraclass correlation coefficient (ICC) were calculated to evaluate repeatability. Intersession ICC was calculated to evaluate reproducibility.
Results::
The intrasession repeatability (2.77 x sw), CVw and ICC of AOD 500 / TIA were 124µm(95%CI 91-155µm) / 7.5°(95%CI 5.6-9.3°), 5.9%(95%CI 4.4-7.4%) / 5.6%(95%CI 4.1-6.9%) and 0.96 (95%CI 0.92-0.99) / 0.93 (95%CI 0.84-0.97), respectively, in the light; and 100µm(95%CI 78-122µm) / 7.0°(95%CI 5.2-8.7°), 5.9%(95%CI 4.6-7.2%) / 6.2%(95%CI 4.7-7.8%) and 0.99 (95%CI 0.97-1.00) / 0.96 (95%CI 0.90-0.98), respectively, in the dark. The intersession ICC of AOD 500 / TIA were 0.90 (95%CI 0.78-0.96) / 0.83 (95%CI 0.63-0.93) and 0.91 (95%CI 0.81-0.97) / 0.92 (95%CI 0.83-0.97), in the light and in the dark, respectively.
Conclusions::
The Visante anterior segment OCT demonstrated reliable anterior chamber angle measurement in different lighting conditions. The best repeatability and reproducibility were found in the measurements obtained in the dark.
Keywords: anterior chamber • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • image processing