Abstract
The literature on myopigenesis suggests an active emmetropization mechanism regulated by optical defocus. The strongest evidence comes from compensatory ocular growth in response to lens-induced defocus in different species of animals. Based on these results, it has been suggested that, however useful, spectacle intervention for the optical correction of human myopia would lead to its exacerbation. The present study seeks to evaluate the progression of juvenile-onset myopia in children differentiated by their lens wear patterns. Data from 43 myopes from our longitudinal study of refraction were evaluated, with myopia defined as a spherical equivalent of at least -0.50 D. Refractions were obtained in the laboratory by noncycloplegic retinoscopy performed by one experienced optometrist at regular intervals. Information regarding the subjects' prescription lens-wearing history was obtained from the subjects and their eye care providers. Based on their wearing patterns, subjects were divided into four categories: (1) full-time wearers; (2) myopes who switched from distance to full-time wear; (3) distance wearers; and (4) nonwearers. Exponential functions were fit to the individual refraction data. The age of onset of myopia, the mean myopia at onset of spectacle wear, and the refractive shift over a period of at least 3 years were derived from these fits. Results show that the 3-year refractive shifts are not significantly different among the four groups. A comparison of the extreme conditions, i.e., full-time vs. nonwear categories, also revealed no significant difference when the data were corrected for age effects despite the fact that the nonwearers exhibited an age-adjusted 3-year progression approximately one-half that of the full-time wearers. In summary, the present study failed to demonstrate any overall effects of spectacle intervention on the progression of human myopia. Further investigation using a larger sample is warranted.
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