Corneal epithelial thickness measured by Fourier-domain optical coherence tomography

To characterize the corneal epithelial thickness profile with Fourier-domain optical coherence tomography (FD-OCT).

Epithelial thickness measurements were obtained by FD-OCT within the central 6-mm zone of the cornea in all subjects who were divided into groups of A (0–20 years), B (21–40 years), C (41–60 years), and D (> 60 years) according to age. Profile maps of the central, average, minimum, maximum, standard deviation, every ring, and radiate area of corneal epithelial thickness were plotted. Differences of the epithelial thickness values at the central cornea and peripheral locations were calculated.

The mean epithelial thickness was 54.48 ± 3.11 μm at the central cornea, 53.53 ± 3.06 μm at the 2–5 mm annular area, and 52.45 ± 3.13 μm at the 5–6 mm annular area, with no statistically significant differences between left and right eyes and between both genders. From the center to the edge, the corneal epithelial thickness became thinner obviously for all groups (p  = 0.000), and in the 5–6 mm zone, the epithelial thickness was inversely associated with age (p  = 0.000). The average epithelial thickness map showed that the corneal epithelium was 1.54 μm thicker inferiorly than superiorly (p = 0.000). The thinnest part was on the superior temporal region (52.49 ± 3.48 μm, 50.78 ± 3.68 μm), while the thickest was on the inferior nasal (54.56 ± 3.44 μm, 53.68 ± 3.72 μm).

Corneal epithelial thickness unevenly distributes, with the thinnest part on the superior temporal region and the thickest on the inferior nasal region. The 5–6 mm annular area corneal epithelium becomes thinned with aging, while the central corneal epithelial thickness has no obvious change.