Age-related changes in with-the-rule and oblique corneal astigmatism.

Corneal astigmatism is stable until the age of 50 years; thereafter both keratometric and total corneal astigmatism show a 0.25 D ATR change per 10 years. The average 0.25 D ATR PCA compensates the predominant keratometric WTR astigmatism in the younger patients and increases the TCA in the elderly with keratometric ATR astigmatism. The gender-based differences in age-related astigmatism require further studies.