Abstract
Purpose :
Progressive addition lenses (PALs) have been used as a treatment to slow myopia progression; however, clinical concerns exist about potential long-term effects of PALs on binocular posture. This study investigates the impact of PALs versus single vision lenses (SVLs) on previously reported age-related changes in phoria magnitude in children with myopia.
Methods :
114 myopic subjects (baseline age: 6 to <12 yrs, refractive error range: -1.25 to -4.50D) from the University of Houston College of Optometry COMET cohort were included in this study, with data collected annually for 10 yrs. Subjects were randomized to SVLs or PALs (+2.00D) for the first 5 yrs, with SVLs, PALs, or contact lenses permitted thereafter. Distance and near alternate cover test with prism neutralization was performed annually in adherence with the COMET protocol. During the treatment phase of the study (years 1-5), distance and near phoria were measured through trial framed distance refractions by masked examiners. In years 6-10, examiners were unmasked to the subject treatment groups and phoria was measured through subjects’ presenting correction modalities, with the exception of the 6 who elected to remain in PALs and were tested with a trial frame, or the distance portion of their PALs. A linear mixed modeling approach was used to compare change in phoria magnitude over time between the two treatment groups for both distance and near measures with negative values indicating exophoria and positive values indicating esophoria.
Results :
Baseline phoria did not differ between groups at distance (PALs: -0.02±2.2pd, SVLs: -0.2±2.3pd, p=0.60) or near (PALs: 2.3±4.3pd, SVLs: 2.5±5.9pd, p=0.88). There was no overall significant change in distance phoria over 10 years (p=0.15), but there was a significant change in near phoria in the exophoric direction (-0.48pd/yr, p<0.001), as previously reported. Application of linear mixed modeling to evaluate the effect of PALs now demonstrates the rate of change in near phoria over time was not significantly different by treatment group (PALs group: 0.13 pd/yr less than the SVLs group, p=0.098).
Conclusions :
Distance phoria remained stable throughout the study duration, whereas near phoria became more exophoric over time. There was no observed long-term effect of PALs on phoria magnitude.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.