Adult Myopia Progression.

Purpose: To explore evidence for myopic shift between the ages of 20 and 50 years.

Methods: Three usable sets of data with long-term adult refractive progression were identified: (1) US population-based prevalence data for those 18 to 24 years of age in 1971 and 1972 and 45 to 54 years of age from 1999 to 2004; a logit transformation of prevalence values at different refractive error thresholds allowed estimation of myopic progression in this group. (2) German clinical data describing 5- to 10-year progression for different refractive error groupings across 5-year age bands from 20 to 49 years; these were extracted, adjusted, and analyzed. (3) Five-year progression rates with similar breakdown of age and refractive error groups as the German data but in a Japanese clinical population.

Results: Estimates of progression between 20 and 50 years for the given studies were: (1) -1.1, -1.4, and -1.9 diopters (D) for baseline refractive errors of -1, -3, and -6 D, respectively; (2) a range from -1.0 to -2.9 D, increasing with degree of baseline myopia; (3) a weighted average of -1.0 D for males and -0.9 D for females but with decreasing progression with increasing myopia. In all studies, average progression rates fell with increasing age, with most progression occurring between 20 and 30 years.

Conclusions: All three studies provide evidence of around -1 D myopia progression between the ages of 20 and 50 years. This has implications for intervention to slow progression during adulthood, as well as projections of visual impairment associated with myopia.