Amplitude of accommodation in an 11- to 17-year-old Iranian population.

PURPOSE: The aim was to determine normal values of accommodative amplitude (AA) during adolescence in Iran. METHODS: In this cross-sectional study, sampling was done from high school students in Kermanshah in 2015 through a multi-stage cluster sampling method and selected students were invited to participate in the study. Examinations were performed on-site at each sampled high school. All students had visual acuity and refractive examination followed by measurement of AA. Accommodative amplitude was tested with Donder's push-up method using a Royal Air Force (RAF) near point rule. RESULTS: Of the 1,070 selected students, 901 were included in the study and their mean age was 14.4 ± 1.7 years. Mean AA in this study was 11.53 ± 3.02 D (range: 5.00-28.50 D). Mean AA was 15.33 D in 11-year-olds and significantly decreased with age, until it reached 10.40 D in the 17-year-old age group. Mean AA in boys and girls were 10.09 ± 2.48 D and 11.65 ± 3.03 D, respectively. Based on the multiple linear regression model, younger age (coefficient = -0.774) and female gender (coefficient = 1.060) significantly associated with AA. CONCLUSION: This study showed that the AA in Iranian teenagers is lower than that calculated with Hofstetter's formula. It is important to take account of this point when making diagnostic and therapeutic decisions.