In vivo assessment of corneal epithelial cells in orthokeratology lens wearers

Abstract

Purpose : Central corneal epithelial thinning associated with mid-peripheral epithelial thickening has been reported as the main factor contributing to the effectiveness of orthokeratology (ortho-k) in myopia control. Yet the cellular mechanism governing the regional change in refractive power remains elusive. This study aimed to evaluate the correlation between the regional change in corneal epithelial thickness and cell density in ortho-k wearers

Methods : A new human prototype of polarization-dependent optical coherence microscopy (POCM) was developed to enable non-contact and non-invasive in vivo imaging of corneal epithelial cells in four ortho-k wearers with and without their ortho-k lens. The epithelial thickness and cell density were evaluated at the central and mid-peripheral corneal locations

Results : POCM achieved in vivo volumetric imaging of all epithelial cell types in ortho-k wearers with and without their lens over a field of view (FOV) of 0.5 x 0.5 mm² with an isotropic resolution of ~2.2 mm and a speed of one volume (500 x 500 x 2048 voxels) per second. It was observed that the nasal epithelium was on average 13.24% thicker than the temporal epithelium, which was also 16.40% thicker than the central epithelium. Cell density was 10.51% higher at the temporal mid-peripheral cornea compared to the central cornea and was also 6.49% higher at the central cornea compared to the nasal mid-peripheral cornea. There was no strong correlation between epithelial thickness and cell density, especially at the mid-peripheral cornea

Conclusions : Although the sample size was relatively small to infer a conclusive statistically significant correlation between regional epithelial thickness and cell density in ortho-k wearers, this study constitutes our first step toward uncovering the cellular mechanism underlying the effectiveness of ortho-k in myopia control. Future studies will focus on the longitudinal evaluation of epithelial cell dynamics in new ortho-k wearers before and during the treatment.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

Fig.1 POCM images of a 31 y.o. ortho-k wearer. (A1-A3) Cross-sectional images of the corneal with ortho-k showing distinct epithelial cells and the gap between ortho-k and the cornea filled with tear film fluid at the reverse zone. (B1-E3) En-face images at different depth locations of the anterior corneal depicting different cellular structures of the corneal epithelial cell types