In-vivo imaging of keratoconic corneas using high-speed high-resolution swept-source OCT

Keratoconus (KC) is a progressive degenerative corneal disease that can lead to a strong deformation of the cornea and loss of clarity, causing distorted or blurred vision. Surgical treatment for severe cases requires precise evaluation of the corneal curvature, thickness, layer structure, and clarity. Current clinical instruments for assessing the corneal shape cannot resolve the internal structure, and high-resolution microscopy techniques are limited to a small field of view. We have implemented a swept-source OCT (SS-OCT) system that enables high-speed imaging (100 kA-scans/s) of the entire cornea and provides similar to 5.1 mu m axial resolution in corneal tissue. With an imaging range of 5.6 mm (in air), we can cover the full length from the cornea's apex to the anterior surface of the lens. We have acquired volumetric corneal images from human subjects with different stages of KC and from subjects who underwent surgery or cross-linking therapy. We developed an automatic algorithm for segmenting the outer and inner surfaces of the cornea in the images which will enable precise measurement of the corneal curvature and thickness. This makes SS-OCT an ideal instrument for comprehensive examination of keratoconic corneas.