Is an objective refraction optimised using the visual Strehl ratio better than a subjective refraction?

Abstract

Purpose To prospectively examine whether using the visual image quality metric, visual Strehl (VSX), to optimise objective refraction from wavefront error measurements can provide equivalent or better visual performance than subjective refraction and which refraction is preferred in free viewing. Methods Subjective refractions and wavefront aberrations were measured on 40 visually-normal eyes of 20 subjects, through natural and dilated pupils. For each eye a sphere, cylinder, and axis prescription was also objectively determined that optimised visual image quality (VSX) for the measured wavefront error. High contrast (HC) and low contrast (LC) logMAR visual acuity (VA) and short-term monocular distance vision preference were recorded and compared between the VSX-objective and subjective prescriptions both undilated and dilated. Results For 36 myopic eyes, clinically equivalent (and not statistically different) HC VA was provided with both the objective and subjective refractions (undilated mean ±SD was −0.06 ±0.04 with both refractions; dilated was −0.05 ±0.04 with the objective, and −0.05 ±0.05 with the subjective refraction). LC logMAR VA provided by the objective refraction was also clinically equivalent and not statistically different to that provided by the subjective refraction through both natural and dilated pupils for myopic eyes. In free viewing the objective prescription was preferred over the subjective by 72% of myopic eyes when not dilated. For four habitually undercorrected high hyperopic eyes, the VSX-objective refraction was more positive in spherical power and VA poorer than with the subjective refraction. Conclusions A method of simultaneously optimising sphere, cylinder, and axis from wavefront error measurements, using the visual image quality metric VSX, is described. In myopic subjects, visual performance, as measured by HC and LC VA, with this VSX-objective refraction was found equivalent to that provided by subjective refraction, and was typically preferred over subjective refraction. Subjective refraction was preferred by habitually undercorrected hyperopic eyes.

Comparison of Two Wavefront Autorefractors: Binocular Open-Field versus Monocular Closed-Field

“…e results of the current study concerning the VX110 also contrast with other authors that did not report differences in the spherical refraction between the newest wavefront autorefractors and subjective refraction [2,[15][16][17][18]. Nevertheless, some authors reported more negative sphere values with different wavefront aberrometers in comparison with subjective refraction during the last decade [8,32,[34][35][36], coinciding with the results obtained with the VX110 in the current study. No studies assessing the performance of commercial open-field wavefront autorefractors were found in the scientific literature.…”

Evaluation of the Performance of Algorithm-Based Methods for Subjective Refraction

“…Instrument myopia can be induced with closed-field view of the autorefractometers and whether there is a fogging step used during autorefractometer measurement [ 5 , 6 , 7 ]. Image quality metrics based on the wavefront data is also widely used to optimize the objective refraction and predict the subjective image quality [ 8 , 9 , 10 , 11 ].…”

Visual and Physiological Optics: where will the journey lead us in 10 years?

“…The meeting also saw many contributions in the field of wavefront aberrations, such as the work by Hastings et al . that proposed using the visual Strehl visual quality metric to optimize the objective refraction.…”

“…The meeting also saw many contributions in the field of wavefront aberrations, such as the work by Hastings et al 8 that proposed using the visual Strehl visual quality metric to optimize the objective refraction. In myopic subjects these objective refractions led to visual acuities that were equivalent to those obtained by subjective refractions, but the subjects tended to prefer the objective refraction.…”