[Corneal astigmatism among 2 085 age-related cataract patients before surgery]

Objective: To investigate the characteristics and distribution of corneal astigmatism before surgery among age-related cataract patients in the Hubei area. Methods: Retrospective study. From January 1, 2012 to July 31, 2016, IOL Master measurements of all qualified cataract surgery candidates were retrospectively collected. Descriptive statistical analysis was used to assess the degree, distribution and type of corneal astigmatism. Kolmogorov-Smirnov (K-S) test was used to evaluate the normal distribution of variables. One-way analysis of variance and Kruskal-Wallis test were applied for the comparison of variance for normally and non-normally distributed quantitative data among different age groups. Spearman's rank test was used to assess the relationship between age and corneal astigmatism. Results: The mean age of the 2 085 patients (3 586 eyes) involved was (73.1±9.43) years old, with more women (58.3%) than men. The mean value of corneal curvature was 44.33 D (95%CI: 44.28-44.39), and the mean corneal astigmatism was 1.06 D (range, 0.05 D to 6.74 D). K-S test indicated the distribution of corneal curvature was normal (P=0.18), while corneal astigmatism did not obey the normal distribution (P<0.01). Corneal astigmatism was between 0.25 D and 1.25 D in 67.7% of the eyes, >1.25 D in 29.7%, and<0.25 D in 4.2%. Corneal astigmatism degree increased with the age increase (P<0.01). There was no statistical difference in corneal astigmatism between women and men (P=0.075). However, women had steeper corneal curvatures than men with statistical difference (P<0.01). Corneal astigmatism with the rule was observed in 29.0% of the eyes, while astigmatism against the rule was found in 53.0%. And astigmatism against the rule increased with age. Conclusion: Corneal astigmatism mostly distributes between 0.25 D and 1.25 D in age-related cataract patients who lived in Hubei. Corneal astigmatism degree increased with age, and the dominant type was astigmatism against the rule. There was no difference in astigmatism between men and women patients aged 50 years and above, but in 70- to 79-year-old patients, women had a higher astigmatism degree than men. The corneal curvature of women was steeper than men in general and in each age group. (Chin J Ophthalmol, 2017, 53: 522-527).