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Corneal response to orthokeratology
H A Swarbrick1, G Wong, D J O'Leary
1School of Optometry, The University of New South Wales, Sydney, Australia.
Summary
Orthokeratology reshapes the cornea by redistributing tissue, leading to myopia reduction. This study tracked topographic and pachometric changes, revealing central thinning and midperipheral thickening of the cornea.
Area of Science:
- Ophthalmology
- Corneal Physiology
- Optometry
Background:
- Orthokeratology (OK) utilizes rigid contact lenses to reshape the cornea.
- Understanding the precise corneal changes induced by OK is crucial for myopia management.
Purpose of the Study:
- To investigate the topographic and pachometric corneal changes resulting from accelerated orthokeratology.
- To correlate these changes with refractive error reduction in myopic subjects.
Main Methods:
- Six young myopic subjects (11 eyes) wore accelerated orthokeratology lenses for 28 days.
- Corneal topography and epithelial thickness were measured using the EyeSys system and Holden-Payor optical micropachometer.
- High Dk material (AirPerm; Dk = 88) lenses were employed.
Main Results:
- A significant reduction in myopia of 1.71 +/- 0.59 D was observed after 28 days.
- Central corneal flattening progressed to 0.22 +/- 0.07 mm, accompanied by central epithelial thinning (7.1 +/- 7.1 microm).
- Midperipheral corneal thickening (13.0 +/- 11.1 microm) was noted, suggesting tissue redistribution.
Conclusions:
- The findings indicate that orthokeratology-induced refractive changes are primarily due to corneal tissue redistribution.
- This redistribution involves central thinning and midperipheral thickening, rather than overall corneal bending.
- These mechanisms explain the initial corneal response to orthokeratology lens wear.