Correction of Myopia Evaluation Trial (COMET)

Myopia (nearsightedness) is an important public health problem, which entails substantial
societal and personal costs. It is highly prevalent in our society and even more frequent in
Asian countries; furthermore, its prevalence may be increasing over time. High myopia
contributes to significant loss of vision and blindness. At present, the mechanisms involved
in the etiology of myopia are unclear, and there is no way to prevent the condition. Current
methods of correction require lifelong use of lenses or surgical treatment, which is
expensive and may lead to complications. The rationale for this trial, the Correction of
Myopia Evaluation Trial (COMET), arises from the convergence of research involving (1) the
link between accommodation and myopia in children and (2) animal models of myopia showing
the important role of the visual environment in eye growth. A contribution of this research
is that blur is a critical component in the development of myopia. The primary aim of COMET,
to evaluate the efficacy of progressive addition lenses, a noninvasive intervention, in
slowing the progression of myopia, follows from this line of reasoning. These lenses should
provide clear visual input over a range of viewing distances without focusing effort by the
child. The comparison of myopia progression in children treated with PALs versus single
vision lenses will allow the quantification of the effect of PALs on myopia progression
during the followup period.

The COMET is a multicenter, randomized, double-masked clinical trial to evaluate whether
PALs slow the progression of juvenile-onset myopia as compared with single vision lenses.
The study is a collaborative effort that involves a Study Chair at the New England College
of Optometry; four clinical centers at colleges of optometry in Boston, Birmingham,
Philadelphia, and Houston; and a Coordinating Center at the State University of New York at
Stony Brook.

The sample size goal, 450 children with myopia in both eyes who met specific inclusion and
exclusion criteria, was attained with the enrollment of 469 children in one year. Children
were identified from school screenings, clinic records, and referrals from local
practitioners. Eligible children were randomly assigned to receive progressive addition or
single vision lenses. Participating children are being examined at 6-month intervals
following baseline, for at least 3 years, to measure changes in refractive error and to
update prescriptions, according to a specified protocol. A dilated examination to evaluate
the study outcome measures is performed at the annual study visits. A standardized, common
protocol is used at all centers.

The primary outcome of the study is progression of myopia, defined as the magnitude of the
change relative to baseline in spherical equivalent refraction, determined by cycloplegic
autorefraction. The secondary outcome of the study is axial length measured by A-scan
ultrasonography.

Children between the ages of 6 and 12 years with myopia in both eyes (defined as spherical
equivalent between -1.25 D and -4.50 D in each eye as measured by cycloplegic
autorefraction), astigmatism less than or equal to 1.50 D, and no anisometropia (defined
as a difference in spherical equivalent between the two eyes greater than 1.0 D) are
eligible for inclusion. Exclusion criteria include visual acuity greater than 20/25,
strabismus, use of contact lenses, birth weight less than 1,250 grams, use of bifocal or
progressive addition lenses, or any conditions precluding adherence to the protocol.