Corneal, Limbal, and Conjunctival Epithelial Thickness from Optical Coherence Tomography

PURPOSE: To compare human central corneal, limbal and bulbar conjunctival epithelial thickness in vivo using an Optical Coherence Tomographer (OCT). METHODS: Thirteen healthy human subjects participated in this study. An OCT (Carl Zeiss, Meditec, Dublin, CA) was used to image central cornea, temporal corneo-scleral limbus and bulbar conjunctiva of the left eye. Two images were taken at each location. Thirty central measurements were averaged from each image for quantifying epithelial thickness. RESULTS: In addition to the central cornea and limbal region, a band corresponding to bulbar conjunctival "epithelium" is apparent in OCT images, with respective thicknesses of 54.7 +/- 1.9 microm (mean +/- SD), 79.6 +/- 7.4 microm and 44.9 +/- 3.4 microm that are statistically significant different (repeated measures analysis of variance p < 0.01, post hoc test shows all p < 0.01). CONCLUSIONS: This study demonstrates that it is possible to image the epithelial tissue in humans in vivo using optical coherence tomography, and in these subjects, the corneo-limbal epithelium is the thickest, while the bulbar conjunctival epithelium is the thinnest and the corneal epithelium has intermediate thickness.