Relationship between age, corneal astigmatism, and ocular dimensions with reference to astigmatism in eyes undergoing routine cataract surgery

Purpose To assess the relationship between age, corneal astigmatism, and ocular dimensions with reference to astigmatism correction during cataract surgery. Methods In this cross-sectional study of right eyes of 2247 consecutive patients attending cataract surgery preassessment, data on patient demographics, axial length (AL), anterior chamber depth (ACD), and keratometric astigmatism were collected. Astigmatism was further analyzed as against-the-rule (ATR: steepest meridian 180 +/- 30 degrees), with-the-rule (WTR: 90 +/- 30 degrees), and oblique (OB: 30-60 degrees or 120-150 degrees). Results Mean age, AL, and ACD were 72.28 +/- 13.84 years, 23.99 +/- 1.85mm and 3.08 +/- 0.52 mm, respectively. In all, 20.4% eyes had <= 0.50 diopters (D), 55.2% had 0.51-1.50 D, 7.9% had 2.01-3.00 D, and 3.7% eyes had >3.00 D of astigmatism. Overall, 44.2% of eyes had corneal astigmatism >1.00 D. Average astigmatism in age ranges 40-49, 50-59, 60-69, 70-79, 80-89, and 90+ years were 0.82, 1.04, 1.04, 1.02, 1.15 and 2.01 D, respectively. The magnitude of preoperative astigmatism positively correlated with age (P<0.0001), with increasing and decreasing prevalence of ATR and WTR astigmatism, respectively, with advancing age. The magnitude of ATR astigmatism inversely correlates to AL (P<0.0001). ATR astigmatism is more prevalent with increasing magnitude of astigmatism (P<0.0001). Conclusions A majority of patients for cataract surgery have astigmatism between 0.51 and 1.5D. ATR astigmatism increases, whereas WTR decreases with age. ATR astigmatism inversely correlates to AL. With increasing age, the magnitude of astigmatism increases and ATR astigmatism becomes increasingly prevalent. The likelihood of a patient requiring astigmatic correction increases with age.