Evaluating refraction and visual acuity with the Nidek autorefractometer AR-360A in a randomized population-based screening study.

Abstract

The evaluation of visual acuity (VA) and refraction in the Northern Finland Birth Cohort Eye study was performed using the Nidek AR-360A autorefractometer. The accuracy of the method for this population-based screening study was assessed. Measurements of the refractive error were obtained from the right eyes of 1238 subjects (mean age 47), first objectively with the AR-360A and then subjectively by an optometrist. Agreement with the subjective refraction was calculated for sphere, cylinder, mean spherical equivalent (MSE), cylindrical vectors J45 and J0 and presbyopic correction (add). Visual acuity (VA) was measured using an ETDRS chart and the autorefractometer. The refractive error measured with the AR-360A was higher than the subjective refraction performed by the optometrist for sphere (0.007 D±0.24 D p=0.30) and also for cylinder (-0.16 D±0.20 D p<0.0005). The bias between the measurements of MSE, J45 and J0 was low: -0.07 D±0.22 D (p=0.002), 0.01 D±0.43 D (p=0.25) and -0.01 D±0.42 D (p=0.43), respectively. The amount of add measured by the autorefractometer was higher than the subjective 0.35 D±0.29 D (p<0.0005). There was a statistically significant correlation between VA (p<0.0005) and the difference between the subjective and objective refraction. In 99.2% of the measurements, visual values were within one decimal line of each other. The Nidek AR-360A autorefractometer is an accurate tool for determining the refraction and VA in a clinical screening trial.