Abstract
Abstract: :
Purpose: To examine the topographical corneal shape change across the horizontal meridian after one night of wearing CRTTM corneal reshaping contact lenses for the correction of hyperopia. Methods: Twenty participants wore a CRTTM HDS 100 contact lens in one eye designed to reduce hyperopia .The other eye served as the control. The lens was worn during 8 hours of sleep. Topography and refractive error was measured using the Humphrey AtlasTM corneal topographer the night prior to lens insertion, immediately after lens removal on the following morning and 1, 3, 6 and 12 hours afterwards. Recovery data was gathered 28 hours later. Topographic changes were measured over a 6–8mm chord in 1mm steps. Results: There were significant differences in corneal curvature over time; the central cornea was steepened by 0.85±0.67D (range 0.00 to 2.20D) and at the mid–periphery (3mm temporal from the centre) the cornea flattened 1.70±1.11D (range 0.00 to 4.30D) in experimental eyes (both p=0.000) compared to baseline, while no change was found in control eyes (p=0.139). The central corneal steepening regressed over time 50% centrally and 56% mid–peripherally. (both p=0.000) and did not recover to baseline after 12 hours. At the 28 hour (post–discontinuation) visit, the central cornea recovered to baseline, although it was still steeper (approx. 0.12D) and the mid–periphery was still flatter by 0.25D representing a 98% recovery (both p>0.05). Conclusions: After one night of lens wear, the CRTTM for Hyperopia lens wearing eye showed a moderate although significant central steepening which translates into hyperopic correction . The shape of the cornea did not recover to baseline at 12 hours after one night, but, recovered after 28 hours of no lens wear.
Keywords: contact lens • topography • cornea: clinical science