Comparison of Dynamic Retinoscopy and Autorefraction for Measurement of Accommodative Amplitude.

SIGNIFICANCE

This study promotes the use of dynamic retinoscopy to obtain objective measures of accommodative amplitude (AA) in the clinical setting in lieu of the subjective push-up technique.

PURPOSE

This study compared the agreement between open-field autorefraction and a modified dynamic retinoscopy for the objective measurement of AA.

METHODS

Accommodative amplitude was measured using two objective techniques for subjects aged 5 to 60 years. Test order was randomized and monocular AA was measured as subjects viewed printed letters 0.9 mm in height with their dominant eye and distance refraction. For retinoscopy, subjects held a near rod and viewed the target at the nearest (most proximal) point of clear vision. The examiner then performed dynamic retinoscopy along the horizontal meridian and identified the physical location of neutrality of the reflex, which was converted to AA in diopters. Autorefraction was performed obtaining repeated measures of refraction beginning from a target demand of 2.5 D and increasing in discrete steps until there was no subsequent increase in accommodative response. Refractions were converted to power in the horizontal meridian and expressed as accommodation in diopters with the maximal value termed the AA. Distance overrefractions were measured for both techniques to adjust AA for any uncorrected refractive error. Difference versus mean analysis was used to compare agreement between tests.

RESULTS

The 95% limits of agreement between techniques were calculated after removal of two young outliers who responded poorly to one of the techniques. The overall mean difference for 95 subjects was 0.02 ± 0.97 D, with limits of agreement spanning -1.87 to 1.92 D. No significant linear relationship between the magnitude of the AA and the differences between techniques was observed.

CONCLUSIONS

Agreement between dynamic retinoscopy and open-field autorefraction was less than 2 D with no systematic bias, suggesting that dynamic retinoscopy may be a suitable clinical technique to measure objective AA.