Factors Associated with High Myopia After 7 Years of Follow-up in the Correction of Myopia Evaluation Trial (COMET) Cohort

Purpose: To evaluate factors associated with the development of high myopia (worse than ?6.00 D) over 7 years of follow-up in the COMET cohort. Methods: COMET enrolled 469 ethnically diverse children (6–11 years) with myopia between ?1.25 and ?4.50 D. They were randomized to either progressive addition lenses (PALs) or single vision lenses (SVLs), and followed for 5 years in their original lens assignment and 2 additional years wearing either spectacles (PALs or SVLs) or contact lenses. Refractive error was measured annually by cycloplegic autorefraction and axial length by A-Scan ultrasonography. Myopia for each child was defined as the mean spherical equivalent refractive error (SER) of the 2 eyes. Analyses were based on 7 years of follow-up. Time to high myopia was analyzed by Cox proportional hazard models and linear regression. Parental refraction data were available from 240 COMET subjects. Results: Younger (6–7 years) versus older (11 years) age at baseline was a significant risk factor (adjusted hazard ratio (HR) = 6.6, 95% CI = 3.4, 12.7) for having high myopia within 7 years. More (SER from ?2.26 to ?4.50 D) vs. less (SER from ?1.25 to ?2.25 D) baseline myopia was also a significant risk factor for high myopia at 7 years (adjusted HR = 7.4, 95% CI = 4.4, 12.4). Gender, ethnicity, and treatment assignment were not associated with the risk of high myopia within 7 years. Increased number of myopic parents was associated with a significant risk of high myopia in the children (p = 0.008). Conclusions: Children who developed high myopia during 7 years of follow-up were younger and had more myopia at baseline. They also were more likely to have two myopic parents. These children may be at greater risk for sight-threatening conditions later in life.