Overcorrection as a means of slowing myopic progression.

Thirty-six subjects (18 males and 18 females) ranging in ages from 7.38 to 15.82 years received an overcorrection of 0.75 D over the power required to correct their myopia exactly. These 36 experimental subjects were matched by control subjects selected at random from the files of the Indiana University Optometry Clinics. The criteria used in matching were sex, beginning age, beginning refractive error, and duration of time covered by the record. The mean rate of change of refractive error for the experimental group was (minus indicating increase of myopia) -0.49 D/year (range, +0.37 to -1.95 D/year) on retinoscopy and -0.52 D/year (range, +0.21 to -1.32 D/year) on subjective refraction. The mean rate of change for the control group was -0.47 D/year (range, +0.06 to -2.03 D/year) on retinoscopy and -0.47 D/year (range, +0.28 to -1.72 D/year) on subjective refraction. Rates for the experimental and control groups were not significantly different. The results of this study do not support the hypothesis that an overcorrected myope has a lower rate of increase of myopia than a myope wearing a conventional spectacle correction.