Pilot Study of the Effects of Ambient Light Level Variation on Spectral Domain Anterior Segment OCT-Derived Angle Metrics in Caucasians versus Asians

ABSTRACTPurpose: To investigate the effects of ambient light level variation on spectral domain anterior segment optical coherence tomography (SD-ΟCT)-derived anterior chamber angle metrics in Caucasians versus Asians.Materials and Methods: Caucasian (n = 24) and Asian participants of Chinese ancestry (n = 24) with open angles on gonioscopy had one eye imaged twice at five strictly controlled, ambient light levels. Ethnicity was self-reported. Light levels were strictly controlled using a light meter at 1.0, 0.75, 0.5, 0.25, and 0 foot candle illumination levels. SD-OCT 5-line raster scans at the inferior 270° irido-corneal angle were measured by two trained, masked graders from the Doheny Image Reading Center using customized Image-J software. Schwalbe’s line-angle opening distance (SL-AOD) and SL-trabecular iris space area (SL-TISA) in different light meter readings (LMRs) between the two groups were compared.Results: Baseline light SL-AOD and SL-TISA measured 0.464 ± 0.115mm/0.351 ± 0.110mm2 and 0.344 ...