An autorefractor may measure more central hyperopia than an aberrometer upon refraction of a 5.0 mm pupillary area, according to a study published in Journal of Optometry.
Researchers compared central and peripheral refraction measurements taken by an autorefractor and aberrometer by enrolling 123 children, aged 8 to 18 years in a study. They began by performing a cycloplegic examination with subjective refraction to evaluate visual acuity. They obtained 3 measurements with both instruments along the horizontal visual field up to 30° (both nasally and temporally) in 10° steps, and assessed refractions on a 2.5 and 5.0 mm pupillary diameter.
While researchers observed similar defocus components between the autorefractor and aberrometer at a 2.5 mm diameter for most viewing angles, they noted significant differences with a 5.0 mm pupil in which the autorefractor measured more hyperopia, according to the report. An analysis of central refraction revealed that the autorefractor was 0.30 D more hyperopic than the aberrometer at a 2.5 mm pupillary diameter, and 0.50 D more hyperopic when measuring a 5.0 mm pupil.
The investigation also shows that the repeatability of autorefractor measurements was worse than that of the aberrometer. The autorefractor showed an average variability of 0.29 D for defocus between measurements for central refraction, and the coefficient of repeatability worsened with eccentricity.
Researchers expressed confidence in both instruments with respect to peripheral refraction. “Both instruments showed a similar trend in the relative peripheral refraction and can be used to obtain peripheral refraction in children despite poor repeatability with the [autorefractor],” according to the investigators.
Study limitations include ethnic homogeneity in the study population and failure to account for the effect of eye turns on peripheral refraction measurements.
Demir P, Macedo AF, Chakraborty R, Baskaran K. Comparison of an open view autorefractor with an open view aberrometer in determining peripheral refraction in children. J Optom. Published online January 10, 2022. doi:10.1016/j.optom.2021.12.002