Abstract
Purpose :
There has been no large-scale research to analyze the distribution of prescribed astigmatic axis according to astigmatic power. Therefore, we undertook a fourteen year large-scale follow-up study of 550,000 eyes of Japanese patients who had been prescribed glasses or contact lens (CL) to correct ametropia. The distribution of astigmatic axis, according to astigmatic power, was analyzed.
Methods :
The subject of this study is the 549,985 eyes (glasses: 216,971 eyes, CL: 333,014 eyes) of patients with astigmatism in the 10 to 40 year age range, prescribed glasses or CL to correct ametropia. Prescriptions were made at the Okada eye clinic in Kanagawa, Japan between January, 2001 and December, 2014.
Results :
As a result of analysis, among the glasses wearers, the most common axis was 180° (96,389 eyes (44.42%)), with the next most common being 90 ° (30,495 eyes (14.05%)), followed by 170° (15,739 eyes (7.25%)). Among the CL wearers, the most common axis was 180° (237,932 eyes (71.45%)), followed by 90° (45,904 eyes (13.78%)), and 160° (18,552 eyes (5.57%)).
By dividing the astigmatic power into 5 groups (C < -2.25D, -2.25D ≤ C < -1.75D, -1.75D ≤ C < -1.25D, -1.25D ≤ C < -0.75D, -0.75D ≤ C), the subjects were analyzed by astigmatic power. In both glasses and CL wearers, 180 ° was the most common axis in all groups, but as the astigmatic power got stronger, the ratio of 90° dropped significantly. (glasses: P for trend < 0.0001, CL: P for trend < 0.05).
Conclusions :
The two main axis, 180° and 90°, accounted for 58.47% of the glasses wearers and 85.23% of the CL wearers. Analyzed by astigmatic power groups, 180° was the most common axis among both glasses and CL wearers in all groups. On the other hand, 90° was mainly distributed in the groups with weaker astigmatic power, and for both glasses and CL wearers, there were few 90° axis in the groups with strong astigmatic power.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.