Corneal epithelial morphological changes in orthokeratology lens wearers

PURPOSE: To investigate the utility of in vivo confocal microscopy (IVCM) combined with standardized image grading for identifying early morphological changes in the central corneal and superior limbal basal epithelial cells during short-term orthokeratology (Ortho-K) lens wear, and its potential for identifying subclinical limbal stem cell stress. METHODS: In this prospective study, 12 healthy participants (aged 18-29 years) with no prior Ortho-K experience wore 10.5 mm total diameter Ortho-K lenses for 14 days. IVCM was performed at baseline, Day 7, and Day 14 to assess central corneal and superior limbal basal epithelial cells regularity, and palisades of Vogt (POV) prominence. Clinical assessments included subjective refraction, visual acuity, and corneal topography. IVCM images were graded 0 to 3 (grade 0 = no irregularity, grade 1 = slight irregularity, grade 2 = moderate irregularity, grade 3 = marked irregularity) by three masked examiners. Inter-grader reliability was assessed using intraclass correlation coefficients (ICC), and changes were analysed with the Friedman test. RESULTS: No significant changes were observed in central corneal basal epithelial cells regularity (p = 0.05), superior limbal basal epithelial cells regularity (p = 0.20), or POV prominence (p = 0.61). Inter-grader reliability was moderate for central epithelium (ICC = 0.66) and POV prominence (ICC = 0.62), and low for superior limbus (ICC = 0.46). Clinically, a significant hyperopic shift in spherical refraction (p < 0.001) and central corneal flattening (p < 0.001) occurred, with stable visual acuity (p = 0.86). CONCLUSION: IVCM revealed subtle, non-significant changes in corneal and limbal basal epithelial morphology and POV prominence over 14 days Ortho-K wear. The technique provides a practical, non-invasive approach for monitoring ocular surface health in Ortho-K users. Larger studies are needed to validate these findings and refine diagnostic criteria.