Correction of Myopia Evaluation Trial 2 (COMET2): A randomized trial of the effect of progressive addition lenses versus single vision lenses on low myopia associated with large accommodative lags and near esophoria in children

• To determine if progressive addition lenses (PALs) versus single vision lenses (SVLs) slow the progression of low myopia in children with poor accommodative responses (i.e., large accommodative lags) and near esophoria.

Myopia is a significant public health problem that affects at least 25% of adults in the United States and a much higher percentage of people in Asia. It is a predisposing factor for retinal detachment, myopic retinopathy, and glaucoma, thus contributing to loss of vision and blindness. As might be expected for such a prevalent condition, treatment costs are high. If interventions to retard myopia progression are successful, sight-threatening complications might be avoided and costs should be reduced.

At present, the mechanisms involved in the etiology of myopia are unclear and methods for prevention are unproven. Even without a sound scientific rationale, many options for slowing the progression of myopia have been evaluated. Results of studies using spectacle lenses, mainly bifocals and PALs vs. SVLs, have been equivocal. In addition, compared to single vision lenses (SVLs), bifocals and progressive addition lenses (PALs) are more expensive and their long term effect on accommodation is unknown.

The overall 3-year difference in progression between children wearing PALs vs SVLs in the Correction of Myopia Evaluation Trial (COMET) was 0.20D, statistically significant but not clinically meaningful.

Reduced accommodative responses in association with near work has been shown in previous research to be a factor in the development and progression of myopia. The COMET study found in a secondary analysis that children with larger accommodative lags (> 0.43D for a 33 cm target, based on a median split) wearing single vision lenses (SVLs) had the most progression at 3 years, and that progressive addition lenses (PALs) were effective in slowing progression in these children, with statistically significant adjusted 3-year treatment effects for those with larger lags in combination with near esophoria (0.64D), or lower baseline myopia (0.48D). The treatment effects also were observed in these groups at 1 year and became larger from 1-3 years. These results suggest that PALs are a clinically-viable spectacle treatment for slowing progression in myopic children with large accommodative lags in conjunction with near esophoria and lower amounts of myopia.

The study has been designed as a simple trial that, other than the type of lenses being determined through the randomization process and the addition of accommodation testing using an autorefractor, largely approximates standard clinical practice.

Screening consists of non-cycloplegic procedures of subjective refraction, testing of oculomotor alignment, and testing of accommodative response using the Grand Seiko autorefractor.

Patients who appear to be eligible for the randomized trial will be tested with their eyes dilated to determine whether refractive error in each eye is within the eligibility range for the randomized trial. Patients will be randomized to either progressive addition lenses (PALs) with a +2.00 D addition or to single vision lenses (SVLs). Children will have three years of follow up, with visits every 6 months.

The primary outcome visit is timed 3 years from randomization, with the primary analysis being a comparison of the average change from baseline to 3 years in amount of myopia between children in the single-vision lens group and the children in the progressive-addition lens group. The primary outcome is change in spherical equivalent refractive error (SER) in diopters (D) as measured by cycloplegic autorefraction.

A separate ancillary study nested within the screening process will collect data on two additional methods of measuring accommodation, Monocular Estimate Method (MEM) retinoscopy and Nott retinoscopy. The aim of the ancillary study to help determine whether a simple, effective measure exists that can be easily used by clinicians to identify children with reduced accommodative response who, if they have low myopia and esophoria, might benefit from the treatment with PALs.

Sample Size: The randomized trial will enroll 100 children.

1. Refractive error determined by cycloplegic autorefraction which meets all of the following:
   - Spherical equivalent: -0.50 to -3.00 D in both eyes
   - Astigmatism <=1.5 D in both eyes
   - Anisometropia <=1.00 D difference between eyes in spherical equivalent
   
2. Visual acuity is at least 20/20 with best subjective refraction in both eyes
3. Accommodative response at near (33 cm) is less than 2.00D by non-cycloplegic autorefraction
4. No strabismus present by cover-uncover test at far, near, and/or near with +2.00D over best subjective refraction
5. Near esophoria (>=2.0 PD) present by alternate prism and cover test (APCT) at near using best refractive correction determined from non-cycloplegic subjective refraction
6. No current or prior use of PALs, bifocals, or contact lenses in either eye (prior or current use of SVLs is allowed)

No longer recruiting. Comments: Recruitment began April 2005 and ended on March 31, 2007 with 118 patients enrolled.

Ongoing. Comments: Patient follow up will continue until approximately March 2010.

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