Evaluation of Corneal Epithelial Thickness Imaged by High Definition Optical Coherence Tomography in Healthy Eyes

Purpose: To evaluate corneal epithelial thickness (CET) and corneal thickness (CT) in healthy eyes using spectral domain optical coherence tomography. Methods: Thirty-six healthy eyes were imaged using the Cirrus high-definition (HD)-optical coherence tomography device. The average CET and CT were assessed using Cirrus Review Software within predefined concentric corneal ring-shaped zones. Specific regions of CET (superior, inferior, temporal, nasal, superonasal, inferotemporal, superotemporal, and inferonasal) were also assessed. The difference between zones was compared between males and females. Results: The average CET was 48.3, 47.1, 46.1, and 45.8 mm in the 4 concentric zones (0-2, 2-5, 5-7, and 7-9 mm), respectively (P< 0.001). The average CT was 533.5, 550.8, and 579.4 mm in the 3 zones (0-2, 2-5, and 5-7 mm), respectively (P< 0.001). There was no statistically significant correlation between CET and CT in any of the measured zones. Males had thicker corneas than did females in each of the 3 CT zones (P< 0.05), but CET did not differ significantly. The CET superonasal-inferotemporal in 2.0 to 5.0 mm and CET superotemporal-inferonasal in 5.0-to 7.0-mm zones were significantly thinner in males than in females (21.15 vs. 0.9 mm, 23.5 vs. 21.9 mm), respectively (P< 0.05). Conclusions: Optical coherence tomography-based analysis of CET reveals that it is thinner in the periphery, whereas the total corneal thickness is greater. Although total CT seems to be influenced by sex, CET is not. Regional and sex-based variations in CT may need to be considered when assessing corneal and epithelial alterations in the setting of disease.