Dynamic dark‐light changes in anterior chamber and iris parameters in angle closure patients with novel automatic algorithm using anterior segment optical coherence tomography (AS‐OCT)

Abstract

AbstractPurpose To describe the dynamic dark‐light changes in anterior chamber (AC) measurements and iris parameters in angle closure patients compared to normal angle patients using a fully automatic algorithm developed for anterior segment optical coherence tomography (AS‐OCT).Methods 10 patients (17 eyes with closed angles) and 8 patients (15 eyes with normal angles) on gonioscopic grading were recruited. We acquired images in both dark and light conditions using Visante OCT. Custom software analyzed the images using the iris rim as the landmark instead of the sclera spur. The parameters analyzed included angle opening distance and angle recess area, at 750μm from the iris rim (AOD 750 & ARA 750), AC depth and width, lens vault and iris curvature, thickness, length and area. We analyzed the amount of change from dark to light in both groups of patients.Results In both conditions, angle closure patients had significantly smaller AOD and ARA, but there was no difference in iris parameters between the 2 groups. In both groups of patients, there was significant change in iris length, area, thickness and ARA when moving from dark to light conditions. The AOD changed significantly in normal patients but not in angle closure patients. There was no difference in the magnitude of change in the above parameters, when changing from dark to light conditions, in both groups of patients.Conclusion The automated algorithm can identify differences between the AC measurements and iris parameters in both groups of patients. The lighting condition affects the measurements taken regardless of diagnosis. As such, lighting control should be consistent.