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F. Lu, T. Simpson, L. Sorbara, D. Fonn; Moldability of the Ocular Surface in Response to Local Mechanical Stress . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2390.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the moldability of the ocular surface by examining the acute effects of local mechanical stress on optical performance, corneal shape and corneal/epithelial thickness after corneal refractive therapy for myopia and hyperopia (CRT® and CRT®H).
20 ametropes (spherical equivalent: – 2.08 ± 2.31D) wore CRT® and CRT®H lenses in a random order on one eye (randomly selected). The lenses were worn for three separate time periods of 15min, 30min and 1 hour (randomly ordered, with each time period taking place on a separate day). Refractive errors, aberrations, corneal topography, and corneal/epithelial thickness (using OCT) were measured before and after the lens wear. The measurements were performed on the control eyes at the 1 hour visit only.
With both CRT® and CRT®H lens wear, significant changes occurred in many parameters from the 15min time point. Refractive error, total aberration and defocus decreased after CRT® lens wear (all p<0.05) and increased after CRT®H lens wear from baseline (all p<0.05). Astigmatism did not change (both p>0.05). Higher order aberration (HOA), including spherical aberration (SA) and coma, increased after CRT® and CRT®H lens wear (all p<0.05) from baseline, but the signed SA shifted from positive to negative after CRT®H lens wear (p<0.05). The central cornea flattened and the mid–periphery steepened after CRT® lens wear, whereas the central cornea steepened and mid–periphery flattened after CRT®H lens wear (p<0.05). The central cornea swelled less than the mid–periphery after CRT® lens wear (p<0.05), whereas the central cornea swelled more than the mid–periphery after CRT®H lens wear (p<0.05). The central epithelium was thinner than the mid–periphery after CRT® lens wear (p<0.05) and thicker than the mid–periphery after CRT®H lens wear (p<0.05). Optical performance and corneal curvature did not change from baseline in the control eyes (all p>0.05).
CRT® lenses for myopia and hyperopia induce significant structural and optical changes in as little as 15min. The cornea is a highly moldable tissue.
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