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Elizabeth Shumard, Gareth D Hastings, Raymond A Applegate, Lan C Nguyen, Roxana T Hemmati, Jason D Marsack; Optimizing Spectacle Prescriptions for Patients with Keratoconus. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4213.
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© ARVO (1962-2015); The Authors (2016-present)
To compare visual performance obtained with spectacle lenses determined using the clinically standard subjective refraction to a refraction objectively determined based on visual image quality and wavefront data from subjects with keratoconus.
Ten subjects (n = 19 eyes) with keratoconus underwent a subjective refraction starting from an autorefractor measurement. An optimized objective refraction was also determined by first measuring the total wavefront aberrations of the eye, mathematically applying every possible spectacle correction in the phoropter (at 2° axis steps), and identifying the refraction that provided the best visual image quality determined from the visual Strehl ratio (VSX). Two trial frames were prepared (double blind): one containing the subjective and one containing the objective refraction. High contrast acuity tasks were recorded monocularly for each prescription in a randomized order.
While on average, the mean objective prescription changed visual acuity by –0.04 ± 0.17 logMAR over the subjective refraction, the average change was not statistically significant at the p=0.05 level. When examined by subject, 1 eye gained more than 2 lines, 6 eyes gained between 1 and 2 lines while 4 eyes lost more than 1 line. When asked which of the prescriptions the subjects preferred, subjects chose the objective refraction 73% of the time. When asked to give a free response about their preference of the objective prescription, subjects used words such as “clearer”, “less doubling”, or “less distorted”.
Seventy-nine percent of eyes were either equivalent or gained at least one line in VA with the objective prescription over the subjective refraction, suggesting an optimized objective refractions based on wavefront data would be a useful starting point of spectacle refraction for keratoconus patients.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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