Researchers found a significant increase in astigmatism in participants sampled in the US during the years 1999 to 2008 compared with those in 1971 to 1975 (14% [95% CI: 13.2-14.5] vs 24% [22.8-24.6]), according to an investigation published in the Journal of Cataract and Refractive Surgery. Astigmatism risk increases with age, as well as for patients with myopia, while risk of against-the-rule astigmatism is increased in patients who are men, White, and who do not have myopia, the report shows.
In this retrospective cross-sectional study, researchers examined 4681 US citizens (aged 20-74 years) who completed the National Health and Nutrition Examination Survey (NHANES) during one of the following time periods: 1971 to 1975 and 1999 to 2008. The study uses multivariate logistic regression analysis to examine the influence of demographic variables on rule and presence of astigmatism, as well as assessing changes in prevalence between the 2 periods. The researchers defined astigmatism as 1.0 D or more, and divided patients into the 3 subtypes of against-the-rule (ATR), with-the-rule (WTR), and oblique (OBL). Demographic variables are identified as sex, race, educational level, socioeconomic status, age, and ametropia.
The study shows a 10% increase in prevalence of astigmatism between the 1970s and 2000s populations (14% [95% CI: 13.2-14.5] in 1970s vs 24% [22.8-24.6] in 2000s). This increase was more prominent in men (12% [10.8 to 12.7] vs 23% [21.9-24.2]) than women (16% [14.9-16.8] vs 24% [23.0-25.7]). Researchers conducted an adjusted analysis odds ratio for ametropia on the 2000s population and found that participants with myopia were 8.34 (CI: 7.30-9.54) times more likely to have astigmatism than participants without myopia. The odds of ATR astigmatism is higher in men, patients without myopia, and those aged 60-74 years, the study shows.
This research documents the upward trend of astigmatism cases in the United States between the years of 1971 to 2008 and the impact of race, sex, and aging on decreased vision. Researchers hypothesize this could be due to “thickening of the stromal collagen bundle and decreases in interfibrillar spacing, and this process may occur sooner in men than women” or changes in sex hormone receptors in the eye that occur during aging.
Strengths of this study include the use of detailed national data in the US from the NHANES, use of algorithms that allowed for accurate comparison across time periods and classifications of astigmatism, and the use of multiple logistics regression and confounding variables. The limitations of this study include the exclusion criteria and the use of noncycloplegic refraction in NHANES.
Valluru G, Klawe J, Liu B, Ramulu P, Ahmad S. Characterizing astigmatism in the United States. J Cat Refract Surg. 2022;48(5):519-527. doi:10.1097/j.jcrs.0000000000000786