縦断的にみた視力低下の現状とその要因

概要

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Longitudinal study of visual acuity (VA) from 6 to 17 years old have been carried out using the medical examination records of the graduates of a high school in Akita City in 1978 and 1988. The study subjects were completed their elementary and junior high school in Akita City and their numbers were 114 out of 236 male graduates in 1978 (78M), 54 out of 79 females (78F), 150 out of 322 male graduates in 1988 (88M) and 67 out of 115 females (88F). VA of decimal notation have been changed to visus logarithmus and then the mean values were caliculated. The highest values of mean-VA of each group were 1.21 at 8 years old(y) of 78M, 1.18 at 9y of 78F, 1 .17 at 7y of 88M and 1.15 at 8y of 88F, and their mean-VAs were fallen to about 0.4 at their 17y and the speed of decline of mean-VAs of 88M and 88F were faster than those of 78M and 78F . The cases of the lower vision at 17y showed earlier decline of VA. Stability of VA which showed the same VA more than continuous 3 years were 1.5+ and it seems that the normal VA of Japanese is 1.5 or more. Lower facial mascular strength that comes from the softness of foodstaff s makes trouble to control the mascules participate to lens . It would be a major cause of decline of VA.