Topographic Keratometric Effects of Corneal Refractive Therapy After One Night of Lens Wear

Abstract

Abstract: : Purpose: To compare the extent of the corneal shape change topographically over a horizontal 6-8mm chord after a single night of wearing CRT^TM corneal reshaping contact lenses to wearing control (alignment) lenses and also to compare data collected using Orbscan^TM II and Atlas^TM corneal topographers. Methods: Twenty study participants wore CRT^TM HDS 100 contact lenses in one eye and control lenses (tetracurve design) of the same material in the contralateral eye, overnight. Measurements were performed at baseline on the night prior to lens insertion, immediately after lens removal on the following morning and at 20 and 60 minutes and 3, 6 and 12 hours later. Topographic changes were measured over a 6-8mm chord in 1mm steps. Results: There were significant differences in corneal radius of curvature between the two lenses (p=0.0058) and at various corneal locations (p=0.0000). The mean change in curvature centrally and at the 3mm mid-peripheral point was -1.49±0.73D and 1.96±2.10D respectively, for the CRT lens and -0.37±0.40 D and -0.15±0.92 D for the control lens immediately after lens removal. There were significant changes of shape over time (p=0.0043), but the 12 hour measurements were still significantly different from baseline (p=0.0005). There were strong and significant correlations (r=0.84-0.99, all p<0.05) between Orbscan^TM II and Atlas^TM data topographically, except at the first nasal (1mm) location (r=0.75, p=0.052). Conclusions: Despite only a single night of lens wear, the eye wearing the CRT^TM design had significant topographic keratometric changes compared to the control lens. The shape of the cornea did not recover to baseline values at 12 hours, indicating that the change in shape can be maintained. This work was supported by grants from Paragon CRT^TM Inc and the Canadian Foundation for Innovation (CFI).

Keywords: contact lens • cornea: clinical science • imaging/image analysis: clinical