Purpose
The corneal epithelium plays an important role in maintaining corneal surface smoothness and corneal power. Optical coherence tomography (OCT) is a noninvasive optical imaging technique, considered to be advantageous for imaging corneal epithelium. However, imaging the entire epithelial profile is a challenge. This study was to test the repeatability of measuring the entire thickness profiles of the corneal epithelium in vivo using newly developed ultra-long scan depth and ultra-high resolution spectral domain OCT (SD-OCT).
Methods
A custom-built, ultra-long scan depth SD-OCT was developed based on a complementary metal oxide semiconductor (CMOS) camera and the axial resolution was about ~3.3 μm in tissue. Forty-two eyes of 21 subjects were imaged 2 repeated with 16 lines radically by SD-OCT with high-resolution 2,048 × 4,096 pixels. All eyes were tested twice. The horizontal and vertical corneal epithelial thickness profiles were evaluated by semiautomatic measurement. The coefficient of repeatability (CoR) and intraclass correlation (ICC) of the tests were analyzed.
Results
The full width and depth of the horizontal corneal epithelium was detected, part of the superior corneal epithelium was not shown for covered super eyelid. The mean central corneal thickness is 52.0 ± 3.2 μm for the first measurement and 52.3 ± 3.4 μm for the second measurement (P > 0.05). The epithelial thickness increased towards the limbus. There was no difference between the two tests between horizontal and vertical meridians and right and left eyes (P > 0.05). The ICCs of the two tests ranged from 0.70 to 0.97 and CoRs ranged from 2.5 μm to 7.8 μm from the center to the periphery, corresponding to 5.6% to 10.6% (CoR%).
Conclusions
This study demonstrated the good repeatability of ultra-long and ultra-high resolution CMOS-based OCT to evaluate the entire thickness profiles of the corneal epithelium.
Keywords: 482 cornea: epithelium •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)