Abstract
Abstract: :
Purpose: : To determine the short–term corneal curvature and refractive changes with CRT and Contex OK orthokeratology lenses. Methods: Both eyes of 10 subjects were fitted, using the fitting guidelines provided by the manufacturer, with CRT® and Contex OK orthokeratology lenses. Each lens design was worn by each subject for 60 minutes. The eyes were closed and covered with a mask and the subject was asked to rest in a quite, dark room. Uncorrected visual acuity (UVA), spherical (SPH) and spherical equivalent (SPE) refractive correction, central flat (FK) and steep (SK) curvature were measured before and after lens wear. A three week wash–out period was used in between the tests with the two designs. Results: : Results: The average UVA, SPH, SPE, FK and SK readings before using CRT® and Contex OK lenses was 0.9 (±0.34) LogMAR, –3.63 (±1.74) D, –3.89 (±1.72) D, 44.05 (±1.32) D, and 44.86 (±0.88) D. Post treatment with CRT® and Contex OK orthokeratology lenses the UVA, SPH, SPE, FK and SK was 0.71 (±0.36) LogMAR, –2.99 (±1.84) D, –3.28 (±1.74) D, 43.48 (±1.43) D, and 44.24 (±0.98) D and 0.64 (±0.31) LogMAR, –2.85 (±1.72) D, –3.17 (±1.69) D, 43.59 (±1.3) D, and 44.22 (±0.94) D respectively. There was a statistically significant (p=0.001) difference in the data collected prior to and after each of he lenses were worn. While there is no statistical difference between the refractive and corneal responses to the two lens designs, the Contex OK lens consistently demonstrated a greater change Conclusions: The data shows that on the average, the two lenses produced significant but similar refractive and corneal change when used under a short–term closed eye conditions.
Keywords: myopia • contact lens • refraction