Abstract
Purpose: :
(1) To evaluate the 5–year effect of progressive addition lenses (PALs) versus single vision lenses (SVLs) on the progression of myopia in children enrolled in the Correction of Myopia Evaluation Trial (COMET), and (2) to describe the progression and stabilization of myopia at 5 years in the same children.
Methods: :
COMET enrolled 469 ethnically diverse children (ages 6 – 11 years) with myopia between –1.25 and –4.50 D. They were randomly assigned to either PALs with a +2.00 addition or SVLs, the conventional spectacle treatment, and have been followed for 5 years in their original lens assignment. The primary outcome measure was progression of myopia (spherical equivalent) by cycloplegic autorefraction. Other measurements included accommodative response (AR) and phoria. Analyses were based on the mean of the 2 eyes. Results were adjusted for potentially important factors (e.g., age, sex, AR) with multiple linear regression.
Results: :
After 5 years of follow–up the adjusted progression of myopia (mean ± se) was –1.97 ± 0.09 D in children wearing PALs and –2.10 ± 0.09 D in children wearing SVLs, resulting in a difference of 0.13 ± 0.10 D, which was not statistically significant. This is less than the previously reported 3–year treatment effect of 0.20 ± 0.08 D (p = 0.004). At 5 years children with reduced AR (< 2.56 D for a 33 cm target) and near esophoria had a statistically significant treatment effect of 0.49 ± 0.24 D (p < 0.05). Only 7 % (32/433) of the children had stable myopia at 5 years, defined as a change from the previous year of less than or equal to 0.25 D for 3 years in a row.
Conclusions: :
At 5 years the progression of myopia was similar between children wearing PALs and SVLs. Children with poor accommodation and near esophoria showed a statistically significant treatment effect of approximately 0.50 D, although the clinical significance of this result is uncertain. These children, who often are prescribed PALs or bifocals to improve visual performance, may have an additional benefit of slowed progression of myopia after 5 years. The results also show that the majority of myopic children aged 11 to 16 years have progressing myopia.
Keywords: myopia • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials • refraction