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Is an objective refraction optimised using the visual Strehl ratio better than a subjective refraction?
Author(s) -
Hastings Gareth D.,
Marsack Jason D.,
Nguyen Lan Chi,
Cheng Han,
Applegate Raymond A.
Publication year - 2017
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1111/opo.12363
Subject(s) - strehl ratio , refraction , refractive error , optometry , visual acuity , subjective refraction , contrast (vision) , optics , ophthalmology , medicine , wavefront , mathematics , physics
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 ) log MAR 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 ± S.D. 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 log MAR 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.