Relationship between astigmatism and aging in middle-aged and elderly Japanese

Purpose: To study the effect of aging on astigmatism in adult Japanese. Methods: Measurements of refractive errors and keratometry were performed oil 2161 randomly selected Subjects (aged 40-79 years). The relation between age and the net value in diopters (D) of astigmatism was evaluated with a trend test. The relation between age and the polar value was also examined by linear regression analysis. Results: The mean (+/- SD) value of total and corneal astigmatism was -0.97 +/- 0.72 D and -0.86 +/- 0.63 D. respectively. and the net value of both increased with age (P trend < 0.001). The prevalence of either type of astigmatism also increased with age, according to the Cochran-Mantel-Haenzel test (P < 0.0001 for total and P < 0.01 for corneal astigmatism). The prevalence of against-the-rule astigmatism increased with age for either type of astigmatism (P < 0.0001 for total, P < 0.0001 for corneal). According to the analysis of polar values by age the regression coefficient (+/- SE) for total and cortical astigmatism was -0.024 +/- 0.002 (P < 0.0001) and -0.028 +/- 0.002 (P < 0.0001). respectively. There was no statistical difference between these two regression coefficients. Conclusions: The prevalence of astigmatism increases and the axis turns to against-the-rule with age. The result of the linear regression analysis indicates that the age-related change in astigmatism is mainly associated with changes in the cornea. (c) Japanese Ophthalmological Society 2005.