Comparison of Push-Up and Minus Lens Techniques for Measuring Amplitude of Accommodation in Emmetropic Individuals: A Cross-Sectional Study

Abstract

Background: Amplitude of accommodation (AA) is a key clinical measure of near focusing capacity that declines with age and is used to identify accommodative dysfunction. Common subjective techniques—push-up and minus lens—often yield different AA values, complicating clinical interpretation and comparability across studies. Objective: To compare AA measured using push-up and minus lens techniques in emmetropic individuals and to evaluate age-related variation in technique-derived differences. Methods: A descriptive cross-sectional observational study was conducted at Chaudhry Muhammad Akram Teaching Hospital, Lahore, Pakistan (October 2021–July 2022). Seventy-five emmetropic participants aged 7–35 years (38 males, 37 females) were enrolled using purposive sampling (25 per age group: 7–12, 13–20, 21–35). Monocular AA was measured using a Royal Air Force (RAF) ruler with push-up and minus lens techniques under standardized conditions. Paired comparisons were performed using paired t-tests; correlations were assessed using Pearson’s r (SPSS v25; p<0.05). Results: Push-up AA exceeded minus lens AA across all age groups (all p<0.001). Mean AA (push-up vs minus lens) was 15.52±1.08 D vs 13.48±1.03 D (7–12), 12.16±1.37 D vs 9.72±1.27 D (13–20), and 9.76±1.02 D vs 6.80±0.95 D (21–35). The overall mean paired difference was 2.48 D (95% CI 2.12–2.84; p<0.001), increasing with age (2.04 D to 2.96 D). Conclusion: Push-up technique systematically overestimates AA relative to the minus lens method in emmetropic individuals, with a clinically meaningful discrepancy that increases with age; technique consistency is essential for accurate diagnosis and follow-up.