Abstract
Abstract: :
Purpose: To map corneal thickness with a high–speed corneal and anterior segment optical coherence tomography (CAS–OCT) system. Methods: A high–speed (2000 a–scan/sec) 1.3–micron wavelength CAS–OCT prototype with an internal fixation device was used. The cornea was scanned within a 10–mm diameter area with 8 lines arranged in a radial spoke pattern centered on the apex reflection. Each 1024 axial–scan dataset was acquired within 0.5 second. We developed automated computer processing for 3–dimensional corneal reconstruction and measurement. Corneal thickness was measured normal to the anterior surface and presented as color pachymetry maps and sector statistics. The maps divided into a central region (<2mm) and 3 rings by diameter (pericentral, 2–5mm; transitional, 5–7mm; periphery, 7–9mm). The rings are subdivided into 4 quadrant sectors. The mean and minimum pachymetry were computed for each sector. 10 eyes of 5 normal subjects were scanned 3 times. Reproducibility is assessed by pooled standard deviation of repeat measurements. Results: The population average for mean corneal thickness in the central region was 575 microns. The reproducibility of average corneal thickness was 2.2 microns in the central region, 2.6 microns in the pericentral sectors, and 2.8 microns in the transition sectors. The reproducibility of minimum central thickness was 4.2 microns. Conclusions: High–speed OCT provided non–contact, rapid, and repeatable pachymetric mapping over a wide area. This could be valuable for the planning of keratorefractive procedures and diagnosis of corneal diseases.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • cornea: clinical science • refractive surgery