Detailed Distribution of Corneal Epithelial Thickness and Correlated Characteristics Measured with SD-OCT in Myopic Eyes.

Yanan Wu,Yan Wang

doi:10.1155/2017/1018321

Abstract

Purpose To investigate the detailed distribution of corneal epithelial thickness in single sectors and its correlated characteristics in myopic eyes. Methods SD-OCT was used to measure the corneal epithelial thickness distribution profile. Differences of corneal epithelial thickness between different parameters and some correlations of characteristics were calculated. Results The thickest and thinnest part of epithelium were found at the nasal-inferior sector (P < 0.05) and at the superior side (P < 0.05). respectively. Subjects in the low and moderate myopia groups have thicker epithelial thickness than those in the high myopia group (P < 0.05). Epithelial thickness was 1.39 μm thicker in male subjects than in female subjects (P < 0.001). There was a slight negative correlation between corneal epithelial thickness and age (r = −0.13, P = 0.042). Weak positive correlations were found between corneal epithelial thickness and corneal thickness (r = 0.148, P = 0.031). No correlations were found between corneal epithelial thickness, astigmatism axis, corneal front curvature, and IOP. Conclusions The epithelial thickness is not evenly distributed across the cornea. The thickest location of the corneal epithelium is at the nasal-inferior sector. People with high myopia tend to have thinner corneal epithelium than low–moderate myopic patients. The corneal epithelial thickness is likely to be affected by some parameters, such as age, gender, and corneal thickness.

Highlights

The corneal epithelium plays a very important role in protecting eyes as it is the outermost layer and in maintaining high optical quality [1, 2] as well
It is found that the epithelium contributed 0.85 D alone in corneal refraction at the 3.6 mm diameter zone [3]
The corneal epithelial thickness is not of homogeneous depth and tends to alter its thickness profile to compensate for irregular corneal stromal surface to get a regular surface [4]

Summary

Introduction

The corneal epithelium plays a very important role in protecting eyes as it is the outermost layer and in maintaining high optical quality [1, 2] as well. Since the corneal epithelium contributes a lot in corneal refraction and it helps in the design of the above surgeries, it is very important to get a better knowledge of the characteristics of corneal epithelial thickness distribution. A few instruments have been invented and applied to corneal epithelium thickness measurement in vivo, including very high-frequency (VHF) digital ultrasound and confocal microscopy. A few studies on corneal epithelial thickness mapping have been done using very high-frequency (VHF) digital ultrasound and confocal microscopy [6,7,8].

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