In orthokeratology (overnight corneal reshaping contact lenses) for myopia control, the primary mechanism of axial elongation inhibition is:

• A Flattening of central cornea shifts focus to retina, stopping global stretch
• B Contact lens pressure on the globe prevents axial elongation mechanically
• C Peripheral retinal defocus created by mid-peripheral corneal steepening sends stop-growth signals ✓
• D Reduced accommodative demand during lens wear inhibits ciliary muscle-mediated growth

Explanation

Orthokeratology lenses flatten the central cornea (correcting myopia) while steepening the mid-peripheral cornea. This creates myopic defocus in the peripheral retina (peripheral retinal images fall in front of the retina), which generates 'stop growth' signals from peripheral retinal amacrine cells. Peripheral myopic defocus is believed to inhibit axial elongation via dopamine and other local growth regulators. This contrasts with conventional glasses or contact lenses that correct central vision but create peripheral hyperopic defocus — a signal that may paradoxically stimulate axial growth. Studies show 40–50% reduction in axial elongation with orthokeratology.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.