Visual performance and aberration in keratoconus: A comparison between rigid gas-permeable and soft contact lenses—A pilot study

Abstract

Purpose: To compare visual functions (visual acuity (VA) and contrast sensitivity (CS)) and aberration patterns of keratoconus (KC) patients using spectacles and specific design contact lenses (rigid gas permeable and silicone hydrogel). The outcomes will improve the Optometric management of the disease. Method: This is a pilot study involving 13 eyes from 9 newly diagnosed keratoconus subjects. Subjects were fittedwith RGP and SH contact lenses. The VA and CS were measured using Snellen and Pelli-Robson charts respectively. Ocular aberrationsweremeasured using OPD scan II. All measurements were conducted before (during spectacles wear) and after contact lens wear. Results: Significantly better VA was obtained with RGP than spectacle or SH (P<0.001). Insignificant difference was detected in CS values between RGP and SH (P=0.06). Both SH and RGP significantly reduced total ocular and higher-order aberrations (HOAs) (P<0.001) than spectacles but RGP reduced trefoil, coma and spherical aberrations more than SH. Insignificant difference was also detected in astigmatic aberrations between RGP and SH (P=0.12). Negative correlation was noted between VA and coma aberration (P=0.04) and CS showed strong negative correlations with HOAs, coma, trefoil and astigmatic aberrations. Conclusions: The RGP lenses provided better VA and greater reduction of aberrations than spectacles or SH lenses in keratoconic eyes. However, more data is needed to confirm these findings. Dr. Bariah Mohd-Ali is a Professor and Optometrist at the Optometry and Vision Science Program, University Kebangsaan Malaysia. She is involved in teaching contact lens courses for undergraduate and postgraduate students and is fundamental in the development of specialty contact lens clinic within the university.