Orthokeratology (Ortho-K) lenses slow myopia progression in children by which proposed primary mechanism?

• A Increasing accommodative lag to reduce near-work-related axial elongation
• B Increasing retinal illuminance through improved contrast sensitivity
• C Reducing choroidal thinning by mechanically compressing the globe
• D Reducing axial length growth by flattening central corneal curvature and creating peripheral myopic defocus ✓

Explanation

Ortho-K lenses flatten the central cornea, correcting myopia for daytime wear. The off-axis (mid-peripheral) cornea bulges, creating myopic defocus on the peripheral retina. This peripheral myopic defocus signal inhibits axial elongation by promoting choroidal thickening and slowing scleral remodeling. Multiple RCTs (ROMIO, BE-SMART, CANDY) show ~40-50% reduction in axial elongation compared to single-vision spectacles. Low-dose atropine 0.01-0.05% acts centrally on dopaminergic pathways; combination ortho-K + low-dose atropine provides additive myopia control. This distinguishes ortho-K from spectacle correction which provides only central focus correction.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.