A longitudinal study of cycloplegic refraction in a cohort of 350 Japanese schoolchildren. Anisometropia.

The intereye difference of cycloplegic refraction was determined in a cohort of 350 rural Japanese schoolchildren aged 6 to 11 years. The intereye spherical difference remained statistically unchanged throughout 5 years, with mean value ranging from 0.21 to 0.28 D, median from 0.15 to 0.20 D, and the 95th percentile from 0.58 to 0.85 D. The prevalence of 1.0 D or greater spherical anisometropia was up to 3.1%. Linear regression analyses of the longitudinal data from individual children revealed that 295 (84.3%) children and remained unchanged while 55 (15.7%) showed significant increase or decrease in the amount of anisometropia with increasing age. The intereye astigmatic difference was also statistically unchangeable, with mean value ranging from 0.28 to 0.36 D, median from 0.20 to 0.39 D, and the 95th percentile from 0.70 to 0.90 D. The prevalence of 1.0 D or greater astigmatic anisometropia was up to 4.3%. There was a significant correlation between the spherical and astigmatic anisometropia. The results show the current state of intereye refractive difference in Japanese schoolchildren, demonstrating that it remains unchanged and significant anisometropia is rare during school age.