PURPOSE. The purpose of the Correction of Myopia Evaluation
Trial (COMET) was to evaluate the effect of progressive addition lenses (PALs) compared with single vision lenses (SVLs) on
the progression of juvenile-onset myopia.
METHODS. COMET enrolled 469 children (ages 6–11 years) with
myopia between 1.25 and 4.50 D spherical equivalent. The
children were recruited at four colleges of optometry in the
United States and were ethnically diverse. They were randomly
assigned to receive either PALs with a 2.00 addition (n
235) or SVLs (n 234), the conventional spectacle treatment
for myopia, and were followed for 3 years. The primary outcome measure was progression of myopia, as determined by
autorefraction after cycloplegia with 2 drops of 1% tropicamide
at each annual visit. The secondary outcome measure was
change in axial length of the eyes, as assessed by A-scan
ultrasonography. Child-based analyses (i.e., the mean of the
two eyes) were used. Results were adjusted for important
covariates, by using multiple linear regression.
RESULTS. Of the 469 children (mean age at baseline, 9.3 1.3
years), 462 (98.5%) completed the 3-year visit. Mean (SE)
3-year increases in myopia (spherical equivalent) were
1.28 0.06 D in the PAL group and 1.48 0.06 D in the
SVL group. The 3-year difference in progression of 0.20 0.08
D between the two groups was statistically significant (P
0.004). The treatment effect was observed primarily in the first
year. The number of prescription changes differed significantly
by treatment group only in the first year. At 6 months, 17% of
the PAL group versus 30% of the SVL group needed a prescription change (P 0.0007), and, at 1 year, 43% of the PAL group
versus 59% of the SVL group required a prescription change
(P