To investigate the change of refractive error between the full-correction and under-correction treatment groups of myopic anisometropic patients.

This study included 36 patients who had no amblyopia with myopic anisometropia > 3.00 diopters (D) and less than 6.00 D using the cycloplegic refraction test. The patients were divided into two groups involving the full-correction of both eyes (group 1) or full-correction on the less myopic eye and under-correction with −0.50 D of the more myopic eye (group 2). We monitored refractive changes every 6 months for 24 months.

At the first visit, the mean refractive error of the less myopic eye was −0.68 ± 0.54 D and that of the more myopic eye was −4.22 ± 0.77 D in group 1. The mean refractive error of the less myopic eye was −0.75 ± 0.58 D and that of the more myopic eye was −4.36 ± 0.73 D in group 2. There was no significant difference between the groups ( p = 0.713 and p = 0.585, respectively). At 24 months, the mean refractive errors of group 1 were −1.27 ± 0.54 D and −4.88 ± 0.81 D, respectively, and that of group 2 were 1.38 ± 0.54 D and −5.59 ± 1.01 D, respectively. The mean refractive error of the less myopic eyes showed no significant difference between both groups ( p = 0.555), but that of the more myopic eyes was significantly different ( p = 0.027). Between both groups, the degree of anisometropia at 24 months was 3.61 ± 0.60 in group 1 and 4.20 ± 0.86 in group 2. Group 2 showed a significant difference and more severe anisometropic changes ( p = 0.022).

Full correction of myopic anisometropia without amblyopia is a better method for reducing the progression of anisometropia.