Abstract
Purpose: :
The Beijing Myopia Progression Study (BMPS) is a three-year clinical trial cross- sectional investigation of the natural history of myopia progression, as well as near-work induced transient myopia (NITM) progression, in children between 7 and 17 years of age. An aim of BMPS is to investigate the magnitude and dynamics of NITM, and its possible relation to the progression of permanent myopia, in children of different age groups and refractive errors. One-year follow-up results of the refractive error changes are being reported here.
Methods: :
A total of 293 children have been followed over the past year, including 149 males and 144 females. The mean ages (years) of these children comprised of primary level and senior grade level were 9.4±1.1 (range: 7.2 to 13.3) and 15.2±1.7 (range: 11.8 to 19.4), respectively. There were a total of 198 myopes, 37 emmetropes, and 58 hyperopes at the initial baseline testing. Refractive group categorization was based on the baseline visit cycloplegic results.
Results: :
Group median (quartile range) (diopter) one-year change in myopia in the primary and senior level students was: -0.75 (-1.13, -0.50) (n=90), and -0.31 (-0.50, -0.13) (n=108), respectively. Group mean change from baseline emmetropia in the primary and senior level students was: -0.75 (-1.13, -0.38) (n=27), and 0.00 (-0.88, 0.13) (n=10), respectively. Group mean change in hyperopia in the primary and junior level was: -0.25 (-0.75, 0.00) (n=55) and -0.13 (-0.25, 0.00) (n=3), respectively. A total of 12 subjects progressed from hyperopia to emmetropia, 1 subject from hyperopia to myopia, and 21 subjects from emmetropia to myopia; the remaining subjects exhibited an increase in their pre-existing myopia.
Conclusions: :
The present findings demonstrate that there were relatively large myopic shifts in refractive error in all three groups after 1 year. These shifts were always larger in the younger group, thus suggesting greater susceptibility to genetic and/or environmental factors in the young children, especially the hyperopes.
Keywords: refractive error development • myopia • accommodation