Subjective Binocular Amplitude of Accommodation and its Association with Refractive Error in a Nepalese Clinical Population

Abstract

Purpose To compare subjective binocular amplitude of accommodation (AA) between myopic and hyperopic individuals and examine its association with age, sex, and refractive error in a Nepalese clinical population. Methods This cross-sectional study included 160 participants aged 11–35 years, comprising 113 with myopia and 47 with hyperopia. Binocular AA was measured using the push-up technique with a Royal Air Force rule. Group differences were assessed using t-tests and analysis of variance, while associations with age, sex, and spherical equivalent refractive error were examined using multiple linear regression. Repeatability and agreement between push-up and pull-away measurements were also evaluated. Results Mean age was 21.49 ± 7.29 years, and 55.6% of participants were female. AA was greater in myopic than hyperopic participants (13.34 ± 2.80 vs 10.76 ± 3.15 D; mean difference 2.59 D, 95% CI 1.53–3.64; P < 0.001). After adjustment for age and sex, the difference remained significant (adjusted mean difference 1.94 D, 95% CI 1.28–2.60; P < 0.001). AA declined with age (r = −0.746, P < 0.001). In multivariable analysis, both age (B = −0.310 D/year) and spherical equivalent refractive error (B = −0.433 D/D) were independently associated with AA (both P < 0.001), whereas sex was not. Push-up measurements showed excellent repeatability (ICC = 0.997), while agreement with pull-away measurements showed a mean bias of 0.53 D and limits of agreement from −1.80 to 2.87 D. Conclusion Subjective AA was greater in myopic than hyperopic individuals and decreased with age. Age and refractive error were independently associated with AA, whereas sex was not. Although push-up measurements were highly repeatable, the limits of agreement with pull-away measurements suggest that the two techniques should not be used interchangeably for individual assessment.