A study on Central Corneal and Corneal Epithelial Thickness Distribution in Myopic Eyes Using Spectral Domain Optical Coherence Tomography (SD-OCT)

Abstract

Background: Myopia is a leading refractive error worldwide, with rising
prevalence in India, particularly in South Tamil Nadu. Corneal and epithelial
thickness play a vital role in ocular health and surgical outcomes, particularly
in myopic patients.
Objective: To evaluate and compare the distribution of central corneal and
epithelial thickness in myopic eyes using Spectral Domain Optical Coherence
Tomography (SD-OCT) among a South Tamil Nadu population.
Methods: A prospective observational study was conducted involving 150
myopic eyes (MRSE -0.50D to -12.00D) of patients aged 10–40 years.
Participants were categorized into low, moderate, and high myopia groups.
Corneal and epithelial thickness were measured using SD-OCT across
central, paracentral (2–5 mm), and midperipheral (5–6 mm) zones. Sectorwise epithelial thickness was also analyzed.
Results: A significant decrease in central corneal thickness was observed
with increasing myopia (p = 0.001). Epithelial thickness followed a similar
trend, with high myopes showing thinner epithelium compared to low and
moderate myopes. The nasal-inferior sector consistently showed the thickest
epithelium, while the superior sector was the thinnest. A negative
correlation was noted between epithelial thickness and age (r = -0.28, p =
0.03), and a positive correlation with MRSE (r = 0.31, p = 0.02).
Conclusion: Corneal epithelial thickness shows significant variation with the
severity of myopia and across different corneal regions. High myopia is
associated with thinner epithelial layers. These findings underscore the
importance of epithelial mapping in refractive surgery planning and myopia
management, particularly in populations with high prevalence like South
Tamil Nadu.