Anisometropia and Changes in Anisometropia in School Myopia

Human anisometropia and changes in it were followed over a 3-year period in 238 schoolchildren who had uncomplicated school myopia in both eyes. Anisometropia of the spherical equivalent (ASFE) type increased in 27%, decreased in 6%, and remained unchanged in 67% of these children. When mean myopia increased from -1.43 to -3.06 D, mean ASFE increased from 0.30 to 0.51 D and the anisometropia of astigmatism (AAST) from 0.15 to 0.23 D. The faster the increase in myopia the greater was the increase in ASFE (r = 0.133, N = 238, p = 0.020). The higher the spherical equivalent at the end of the study the higher was the ASFE (r = 0.135, N = 238, p = 0.019). The initial refractive error or the amount or the axis of astigmatism did not have any prognostic value for the changes in ASFE. The higher the ASFE at the end of the study the higher also was the AAST (r = 0.136, N = 238, p = 0.018). The change in ASFE was independent of the wearing of spectacles. The distribution of the anisometropia of the spherical equivalent and its change followed a nearly normal distribution with the peak of eyes at about +/- 0 refraction.