Changes in Corneal Astigmatism With Age

An analysis of the changes in corneal astigmatism over a mean period of 24.14 years was performed on data obtained by repeated keratometric measurements of the corneas of clinical patients. Patients aged 5 to 29 years at the time of their first measurement showed, as they aged, an increase in the amount of with‐the‐rule corneal astigmatism (or a decrease in against‐the‐rule) at an average rate of 0.0033 D a year. Those aged 30 and over showed a change in the direction of increasing against‐the‐rule at a mean rate of (0.0057 D) a year. However, the corneas of more than 70% of all these patients manifested a change of 0.25 D or less in their astigmatism in 10 years. Changes in the axis of corneal astigmatism averaged less than 4 degrees in 10 years. In over 70% of the subjects the axis was shifted closer to the 90th meridian and in 20% the axis shifted closer to the 180th meridian. The small size and random nature of these changes suggest that these statistical trends offer limited guidance for predicting changes in a specific patient's astigmatic error.