Effect of bifocal lenses on the rate of childhood myopia progression.

Longitudinal records obtained from three optometry practices in the central United States were used to assess the effect of bifocal lenses on the rate of childhood myopia progression. Rates in D/year were derived by linear regression for age spans between 6 and 15 years of age. Records were available for 52 persons who wore single vision lenses (SV group) during this entire age span, and 60 persons who wore bifocal lenses (BF group) during the complete period of observation. The mean rates of myopia progression were -0.44 D/year for the SV group, and -0.37 D/year for the BF group (difference not statistically significant). When rates were determined as a function of nearpoint phoria and near binocular cross cylinder net, the BF group had rates of myopia increase which were lower in magnitude than the SV group in children with nearpoint esophoria and of higher cross cylinder net.