Reproducibility and accuracy of measurements with a hand held autorefractor in children

Abstract

Aim: To determine reproducibility and accuracy of the Nikon Retinomax autorefractor when used with children who were made cycloplegic.

Methods: Autorefraction and retinoscopy or subjectively refined retinoscopy (where, under the patient's direction, the refraction was varied until the best visual acuity was achieved) were performed on the right eye of 47 children, age 11-93 months. Autorefraction was performed using the Nikon Retinomax, which provides up to eight measured values of refractive error and one representative measurement of refractive error.

Results: Autorefractor measurements were successfully obtained from 7/9 children age 3 years or younger, and from all older children. Vector methods were used to calculate differences. Retinomax reproducibility averaged 0.43 D. Unbiased Retinomax and retinoscopy measurements differed by an average of 0.82 D. Unbiased Retinomax and subjectively refined retinoscopy differed by an average of 1.03 D.

Conclusions: Reproducibility of Retinomax measured values in children is comparable with reproducibility of retinoscopy, subjective refraction, and autorefraction measurements in adults. Agreement between Retinomax and retinoscopy and agreement between Retinomax and subjective refinement in children is comparable with agreement between autorefraction and subjective refraction in adults. The study indicates that the Retinomax is a useful instrument for measuring refractive errors in young children.

Figure 1

Individual subjects' Retinomax measured values plotted by age of subject. Circles represent the vector dioptric difference between each Retinomax estimate of a subject's refractive error and the average dioptric value¹³ of that subject's measured values. The Retinomax representative measurement of refractive error is not the mean of the individual measured values, as outliers are discarded.