Orthokeratology contact lenses achieve their refractive correction through which mechanism?

• A Permanent laser-like photoablation of anterior stroma
• B Scleral compression reducing axial length
• C Mydriasis during daytime wear eliminating accommodation requirement
• D Temporary mechanical reshaping of the corneal epithelium during overnight wear ✓

Explanation

Orthokeratology (Ortho-K) uses reverse-geometry rigid gas-permeable lenses worn overnight. The hydraulic pressure pattern from the lens temporarily redistributes corneal epithelial cells — thinning the central epithelium to flatten central corneal curvature and thickening the paracentral epithelium — creating relative myopic defocus in the periphery. This effect lasts through the day providing clear vision without spectacles. The refractive change is fully reversible. Ortho-K also has evidence for myopia control by inducing peripheral myopic defocus.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.