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 theCOMETcohort. 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.