Utilising a visual image quality metric to optimise spectacle prescriptions for eyes with keratoconus

Abstract

AbstractPurposeTo compare optical performance, visual performance, and patient‐perceived quality of vision with: (1) spectacles determined using subjective refraction and (2) spectacles determined using an objective optimisation method based on wavefront aberration data for eyes with keratoconus.MethodsThirty‐seven eyes (20 subjects) with keratoconus underwent both subjective refraction and uncorrected wavefront aberration measurement. Wavefront aberration data were used to objectively identify a sphero‐cylindrical refraction that optimised the visual image quality metric visual Strehl ratio (VSX). The two refractions were assembled in trial frames and worn by the subject in a random order. High‐contrast visual acuity (VA), letter contrast sensitivity (CS), and the patient's short‐term subjective preference were recorded for each prescription.ResultsMedian magnitude of the dioptric difference (a measure of similarity between the subjective and objective refractions) was 2.77 D (range = 0.21–20.44 D, first quartile = 1.02 D, third quartile = 4.36 D). Sixty‐eight per cent of eyes had better VA with the objective refraction and 32% of eyes gained more than one line of VA. Monocularly, objective refraction was preferred 68% of the time when looking at a distant acuity chart and 76% of the time when viewing a real‐world dynamic scene.ConclusionsObjective refraction based on visual image quality derived from wavefront aberration data can be valuable in the determination of monocular spectacle refractions for individuals with keratoconus.