Age‐related changes in with‐the‐rule and oblique corneal astigmatism

Purpose To describe the age‐related changes in with‐the‐rule (WTR) and oblique keratometric astigmatism ( KA ), posterior corneal astigmatism ( PCA ) and total corneal astigmatism ( TCA ). Methods We used a Pentacam HR (high‐resolution) rotating Scheimpflug camera to determine the KA, PCA and TCA in the right eyes of 710 patients, aged from 20 to 88 years. The age‐related changes along the vertical, horizontal and oblique meridians were analyzed with Næser′s polar value method in a cross‐sectional study. Results In the whole group, all meridional astigmatic powers and polar values were stable in the age groups from 20 to 49 years, followed by a 1.0 dioptre (D) against‐the‐rule (ATR) change in KA and TCA , and a 0.12 D reduction in against‐the‐rule PCA . A nasal rotation of the steep meridian in KA and TCA was noted in the 70–88 years old. The PCA averaged approximately 0.25 D ATR in all age groups. Females displayed the same early astigmatic stability as in the whole group, while male eyes demonstrated a linear decay from 1.5 D WTR at 20 years to 0.5 D ATR astigmatism for the oldest patients. Conclusion 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.