Comparison of accommodation amplitude measured by autorefractometry and the negative lens test

Purpose: To compare accommodation amplitude (AA) values obtained using an objective technique (autorefractometry) with those derived from a subjective method (negative lens test). Methods: In this prospective study, 142 participants were stratified into two age groups: <40 years (Group 1) and ≥40 years (Group 2). The dominant eye of each subject was identified using the Miles test. AA was first measured with an autorefractometer (Tonoref III, NIDEK Co., Ltd.) and subsequently with the negative lens test. Anterior segment biometric parameters were also recorded with an optical biometer (LS‑900, Haag‑Streit AG, Switzerland). Measurements were analyzed according to refractive status within each age group. Results: The mean age of the cohort was 36.4 ± 11.9 years (range, 18–60). Mean AA determined by autorefractometry was 1.89 ± 1.74 D, significantly lower than that obtained with the negative lens test (6.01 ± 2.56 D; p<0.001). In Group 1, no significant differences in AA were observed among myopic (n=48), hyperopic (n=10), and emmetropic (n=25) subjects using either method (p=0.430 and p=0.320, respectively). In Group 2, autorefractometric AA was significantly higher in myopic (n=11) and emmetropic (n=18) eyes compared with hyperopic eyes (n=30) (p=0.030 and p=0.020), whereas there was no difference between myopic and emmetropic eyes (p=0.980). Negative lens test results showed no significant intergroup differences (p=0.200). Conclusions: AA values measured with the negative lens test are not interchangeable with those obtained by autorefractometry. Additionally, objective methods yield lower AA values in hyperopic individuals over 40 years of age.