Comparison of Push-Up versus Push-Out Accommodative Amplitude Measurement Methods in a Pediatric Population

Abstract

Purpose : Accommodative amplitude (AA) is often measured using the push-up (PU) method, in which patients report when a target begins to blur as it nears their eye. The push-out (PO) method is an alternative approach, where patients report when a target becomes clear as it moves away from the eye. This study prospectively enrolled children and adolescents to compare the AA obtained using each method.

Methods : Participants meeting the following criteria were included: age 10 to <18 years, no history of amblyopia, 20/25 or better visual acuity in each eye, and wearing appropriate correction if > 2.00 D hyperopia, < -1.00 D myopia, > 1.00 D of anisometropia, or > 1.25 D of astigmatism. PU followed by PO monocular AA was tested three times in each eye (order randomized). Differences between measurements were analyzed using a linear mixed effects model and calculating 95% limits of agreement (LoA) adjusted for inter-eye correlation and repeated measures. Age-appropriate AA was calculated using Hofstetter’s formula; a result less than this value in at least one eye by average AA was considered abnormal.

Results : 57 participants (61.4% female; mean age 13.2 ± 2.3 years; 9 with pre-existing binocular vision diagnoses; 15 concussed in last 6 months) were enrolled. Average AA by the PU method was 11.5 ± 2.8 D (range = 5.1 – 17.7 D) and 11.3 ± 2.7 D (5.4 – 20 D) by PO. On average, AA measured by the PU method was greater than AA by the PO method (0.18 D; 95% CI 0.05 – 0.35; P = .01) after adjusting for testing protocol and inter-eye correlation. AA was greater in the eye that was tested second (0.17 D; 95% CI 0.02 – 0.32; P = .03). Adjusted LoA for PU and PO were [-2.7, 3.2]. 36 participants had age-appropriate AA as measured by both methods; 5 participants were abnormal by only PU, 6 by only PO, and 10 by both methods.

Conclusions : In general, PU gave greater AA measurements than PO, but the wide LoA shows that some participants had PO values greater than PU, suggesting the utility of measuring AA through both methods in a pediatric population. One possible explanation for these differences is the ability of a patient to understand the instructions and learn the task throughout testing, which may be supported by the significant effect of the second eye. Given the wide spread of LoA, averaging repeated PU and PO values could provide a more precise measurement of AA.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.