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 comeo-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 mu m (mean +/- SD), 79.6 +/- 7.4 mu m and 44.9 +/- 3.4 mu m 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.