Abstract
Abstract: :
Purpose: To measure anterior chamber (AC) dimensions with a new generation high–speed corneal and anterior segment optical coherence tomography (CAS–OCT) system. Methods: We used a new high–speed (2000 a–scan/sec), wide–field, 1.3µm wavelength CAS–OCT prototype with an internal fixation target. A horizontal section of the anterior segment is captured at 8 frames/sec. A computer program was developed to align and average 8 consecutive frames and measure the AC depth and width (recess–to–recess). The external corneal diameter (white–to–white) was also measured with a surgical caliper and the Holladay–Godwin gauge. Reproducibility was assessed by pooled standard deviation (S.D.) of repeat measurements. 6 eyes of 3 normal subjects were measured twice. Results: The reproducibility of OCT biometry was 0.004 mm for AC depth and 0.038 mm for AC width. The reproducibility of corneal diameter was 0.19 mm for surgical caliper and 0.23 mm for Holladay–Godwin gauge. The mean difference between the OCT AC width and corneal diameter was 0.71 ±0.32 mm with the caliper and 0.86 ±0.28 mm with the gauge. Conclusions: CAS–OCT provides non–contact, convenient, and reproducible measurement of AC dimensions. Reproducibility of AC width with the new high–speed CAS–OCT was more than twice better compared to our previous prototype. The improvement is likely due to the use of an internal fixation target and frame averaging. Estimation of AC width from white–to–white corneal diameter was relatively unreliable (∼0.3 mm SD v. 0.038 mm SD with OCT direct measurement). Validation with a larger study is needed and in progress. High–speed CAS–OCT may improve AC biometry and AC intraocular lens (IOL) sizing.
Keywords: anterior chamber • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • imaging/image analysis: clinical