Purchase this article with an account.
G. Yoon, L. Johns, O. Tomashevskaya, D. Jacobs, P. Rosenthal; Visual Benefit of Correcting Higher Order Aberrations in Keratoconus With Customized Scleral Lens. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3432.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To test the hypothesis that the residual higher order aberrations that are present in keratoconic eyes with the conventional scleral lenses degrade retinal image quality and customized scleral lenses correcting these aberrations have the potential to provide significant visual benefit.
Eleven keratoconic (KC) patients (13 eyes) and one normal eye were recruited in this study. Conventional scleral lenses were fitted to individual eyes and aberration measurements were performed on each eye with the scleral lens on using a Shack-Hartmann wavefront sensor. The aberration was calculated for the subject’s maximum natural pupil size under the mesopic illumination condition. From the measured aberration, the polychromatic modulation transfer functions (MTFs) were calculated to estimate expected improvements in retinal image quality by customizing the scleral lens. Theoretical visual benefit was defined as the ratio of area under the MTFs with customized scleral lens to with the conventional scleral lens.
Mean higher order RMS ± standard deviation in KC eyes with the conventional scleral lens was 0.72 ± 0.56 µm for averaged pupil size (5.33 ± 0.8 mm) which is approximately 3.4 times larger than that of the normal eye with the scleral lens. The most dominant residual higher order aberration in KC eyes with the conventional scleral lens was vertical coma and all keratoconic eyes except for one showed positive sign of vertical coma. The magnitude of both vertical and horizontal coma was 0.67 ± 0.25 µm (mean ± standard deviation). Averaged theoretical benefit with customized scleral lens over the conventional scleral lens was 5.3 ± 1.3. For one of the subjects, the stability of lens position and rotation at various time points was monitored after lens fitting was completed. Negligibly small amounts of decentration and rotation were observed up to 75 minutes.
Although the conventional scleral lens effectively neutralizes the higher order aberration induced by the anterior corneal surface, the significant amounts of the residual aberration were observed. These aberrations are resulted from mainly the posterior corneal surface and limit visual performance. Customized scleral lens has the potential to provide substantial improvement in visual performance stably in keratoconic patients.
This PDF is available to Subscribers Only