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KMID : 1159320170190040403
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Korean Journal of Vision Science
2017 Volume.19 No. 4 p.403 ~ p.410
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Comparison of Changes in Myopia Distribution and the Progressive Rate of Myopia for Generations
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Kim Jung-Hyun
Lee Hyun
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Abstract
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Purpose: To compare changes in refractive error distribution and the progressive rate of myopia in subjects aged 6 to 24 years.
Methods: Data on refractive error for 64,292 subjects (male 15,567, female 48,725) were obtained from optical shops in Chungju and Chunan restricts from 1987 to 2012, and were statistidally analyzed. Progress rate of myopia per a year was determined with factors such as MOD (magnitude of difference) and VDD (vector difference in diopter) of the power vector component, and the number of visiting the optical shops from 1987 to 2012 was applied.
Results: The subjects aged 6 to 24 years were classified into five groups according to an educational system, and also classified by the interval of 5-year. In the distribution of low, moderate and high myopia according to visiting year, low myopia was reduced, moderate and high myopia was increased, the differences of change rate were significant. The mean of refractive errors in all groups except for 6-7 years group were showed statistically significant in the negative direction. The difference in the trend was same in all age groups except for the 6-7 years group. Progressive rates of myopia converted into power-vector showed significantly different in a consecutive visit the times to the optical shops between 8-13 and 14-16 age groups. Progressive rate of myopia according to visit per a year was ?0.344 D in all subjects (p=0.000). The progressive rate of myopia of a 6-15 age group was -0.542 D (p=0.000), and rate was the highest in the age group.
Conclusion: In the same age groups, the mean of refractive error was changed in the negative direction depending on visiting per a year, and the rate of high myopia was higher, the visiting year was closer. In addition, the rate of progressive myopia was appeared to be faster in the present than in the past.
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KEYWORD
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Myopia, Power vector, MOD, VDD, Progressive myopia
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