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V. Fernandez-Sanchez, F. Lara, P. Hernández-Pastor, N. López-Gil; Objective Measurement of the Amplitude of Accommodation Based on Wavefront Outcomes. Invest. Ophthalmol. Vis. Sci. 2007;48(13):973.
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© ARVO (1962-2015); The Authors (2016-present)
Although the amplitude of accommodation (AA) gives relevant information about possible accommodation disorders and the addition prescription, its value depends strongly on the method used (usually subjective). We analyze an objective method to measure the AA based in wavefront measurements.
We evaluated the AA of 100 normal eyes (57 subjects) with ages among 20 and 48 years (24.6± 4.85) using 4 subjective methods: minus-lens procedure, Badal optometer and Push-up method both, with and without convergence. We used an Irx3 aberrometer (Imagine Eyes) to evaluate monocular aberrations while their accommodation was stimulated with a target of vergence varying from 0 (far point) to 10 or more diopters in steps of 0.5 D. Three different metric obtained in the pupil plane which included defocus and spherical aberration (SA) were used to compute the amplitude of accommodation. Subjective and objective values of AA were compared.
Objetive AA based in a metric that takes only into account defocus urderstimated in more than 1 D the AA obtained subjectively. When SA is included in the metrics, objetive AA differs from the one obtained using the Badal optometer or negative lenses in less than a quarter of diopter, not finding significant differences between methods. However, it was found a mean difference between objetive method and Push-up method of 1.69 D, being 1.92 D in the case of push-up with convergence.
AA can be obtained objectively by means of wavefront outcomes if spherical aberration is taken into account in the metric used. Push-up methods overstimates AA in accordance with studies performed previously. The method could be used to obtain objectively the value of the addition in presbyopes.
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