Variables related to the rate of childhood myopia progression.

This study was undertaken to examine the relations between the rate of childhood myopia progression and variables available in patient records. Data were obtained from four private optometry practices and two university-based longitudinal studies. Subjects were myopes with a minimum number of refractions between the ages of 6 and 15 years. Spectacle prescription types included single-vision lenses with exact distance correction or slight undercorrection, bifocal lenses, and single-vision lenses with overcorrection. Rates of progression were determined by linear regression. Three analyses were conducted: (1) for all patients, analysis of variance of rate as a function of heterophoria through the habitual nearpoint correction, an index of the amount of myopia at the initial examination age, sex, and clinical location; (2) for patients with esophoria through the distance ametropia correction, analysis of variance of rate as a function of correction type (full correction or slight undercorrection vs. bifocals), amount of myopia at the initial examination age, sex, and location; and (3) for patients with orthophoria or exophoria with ametropia correction, analysis of variance of rate as a function of correction type, amount of myopia at the initial examination age, sex, and location. The index of amount of myopia at the initial examination age was a significant variable, as was location. Patients with nearpoint esophoria through their habitual nearpoint correction had greater rates than patients with nearpoint orthophoria or exophoria with the habitual correction. For patients with nearpoint esophoria through the distance refractive correction, rates were less with bifocals than with full correction or slight undercorrection.