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Rami Aboumourad, Heather A Anderson; Comparison of two objective techniques for measurement of accommodative amplitude. Invest. Ophthalmol. Vis. Sci. 2017;58(8):324.
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Studies of objective accommodative amplitude (AA) with open-field autorefraction (AR) have shown that the subjective push-up technique over-estimates AA. However, using AR to measure AA in the clinic is not practical and thus alternative objective techniques are needed that could provide more accurate information about AA than the commonly used subjective push-up amplitude test. The purpose of this study was to compare agreement between AR measurement of AA and a recently described objective technique using dynamic retinoscopy (DR).
One hundred subjects aged 5-60 were measured by two AA tests (order randomized) monocularly (dominant eye) while wearing their habitual distance correction and asked to keep clear a 0.9mm tall letter target. For DR, subjects held a near rod and pushed the target away until it became “first clear”. The examiner then viewed the retinoscopic reflex along the horizontal meridian and identified the location from the eye where neutrality was observed, which was then converted to diopters (D) to express AA. For AR, refraction measures were taken as subjects viewed the target first at a 2.5D demand and then subsequent demands increasing in proximity (up to a 30D demand maximum) until no additional increase in accommodation was observed. Refractions were converted to spherical equivalent and expressed as accommodation in D, and the maximum value termed the AA. Distance over-refractions were measured for both techniques and added to the AA to account for any uncorrected refractive error.
The group mean difference between AR and DR was +0.22D (95% LOA = -2.32D to +2.77D diopters), with 88% of subjects having differences between +/-1.50D. Three children were identified as likely outliers with differences between tests of 4.85D or greater (2 responded poorly to DR and 1 responded poorly to AR). Removal of these outliers improved the agreement to +0.16D (95% LOA = -1.73 to 2.05D). There was no significant linear relationship between subject age and the magnitude of the difference with or without the outliers (p≥0.07).
On average, AR measured greater amplitudes; however, the majority of subjects had differences less than 1.50D, indicating DR may serve as a substitute for AR in the clinic to measure objective AA.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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