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Changes in Refraction, Ocular Aberrations and Corneal Structure after Suspending RGP Contact Lens Wear in Patients with Keratoconus

Faculty of Life Sciences, The University of Manchester, Manchester, United Kingdom

Commercial Relationships: Amit N. Jinabhai, None; Hema Radhakrishnan, None; Clare O'Donnell, None

Support: Amit N. Jinabhai is supported by a PhD scholarship from the College of Optometrists (UK).

Abstract

Purpose:This investigation reports on changes in visual acuity, ocular higher-order aberrations and refraction, after suspending RGP (rigid gas permeable) contact lens wear for one week in 16 patients with moderate to severe keratoconus. Alterations in the anterior surface central corneal powers and axes and central corneal thickness were also investigated.

Methods:Scheimpflug photography and Shack-Hartmann aberrometry were performed at two visits, seven days apart, after the patients had removed their habitual RGP lenses. Subjective refraction and both high- and low-contrast logMAR visual acuities were also recorded at both visits.

Results:Reductions in both high- (p = 0.001) and low-contrast visual acuity (p = 0.005), along with an increase in third-order RMS aberrations (p = 0.006), occurred after RGP lens wear was suspended in these keratoconic patients. However, no significant changes in subjective refraction were found over the one-week period (p > 0.082). Significant correlations were observed between third-order coma RMS aberrations and the measured high- (R² > 0.53, p < 0.034) and low-contrast visual acuities (R² > 0.55, p < 0.027). In addition to increases in the anterior surface central corneal powers (p < 0.02), a reduction in central corneal thickness was also found between the two visits (p = 0.00012).

Conclusions:Changes in the optical and structural parameters of the keratoconic cornea occur after suspending RGP contact lens wear. This information may be of interest to practitioners involved with prescribing aberration-controlling soft contact lenses for such patients.

Keywords: keratoconus • aberrations • visual acuity

© 2011, The Association for Research in Vision and Ophthalmology, Inc., all rights reserved. Permission to republish any abstract or part of an abstract in any form must be obtained in writing from the ARVO Office prior to publication.