Prevalence and variation of astigmatism in a military population.

Astigmatism is a common refractive anomaly. Observations on 1112 consecutive patients from a military optometric clinical population were taken to establish the prevalence of astigmatism and the incidence of its different variations. Astigmatism was found to exist in about 63% of the eyes. It was found that with-the-rule (WTR) and against-the-rule (ATR) astigmatism were the predominant types of astigmatism, and that approximately 70% of astigmatism found required 1.00D of correcting cylinder power or less. One objective of the study was to discover if a statistically significant difference existed between right and left eyes when comparing the mean correcting minus cylinder axes for WTR, ATR, and oblique types of astigmatism. This was shown to exist for WTR and ATR astigmatism. Further studies to determine the etiology of this difference are indicated.