Astigmatism Varies Among Age, Gender, Ethnic and Education Groups Interview with:

Sumayya Ahmad, MD Assistant Professor of Ophthalmology Icahn School of Medicine at Mount Sinai

Dr. Ahmad

Sumayya Ahmad, MD
Assistant Professor of Ophthalmology
Icahn School of Medicine at Mount Sinai What is the background for this study?

Response: The cornea is usually curved like a basketball or a globe. Roughly all of the edges are about equal distant from the center. With this shape, light enters the eye normally and the image is not distorted.  However, not all eyes are shaped that way.

About 30% of eyes have  astigmatism, in which the cornea is shaped like a football, or elongated in one axis. If the longest diameter is up and down, we call that with the rule astigmatism, and if it is to the side, we call that against-the rule astigmatism.

A lot of studies have been devoted to astigmatism over the years, but nobody has looked at it from a population perspective in the United States and tried to figure out the relationships it may have. Most studies are from one center or other country’s databases, but not ours. The National Health and Nutrition Examination Survey, or NHANES, is a survey composed in the United States each year that looks at a representative sample of people from across the country. It’s a great way to study the relationship between the environment and people. We tried to look at demographic factors (like age, gender, race) and ocular factors related to against and with the rule astigmatism. What are the main findings?

Response: We found that with the rule (WTR) astigmatism decreased iwih age, and against the rule increased with age. There were higher odds of being WTR for females (1.39), Mexican Americans (1.79), college graduates (1.48) compared to male, non-hispanic whites with less than a 9th grade education.

Myopic patients (or near sighted patients)  had higher odds (1.53) of having WTR astigmatism than people who did not have far or near-sightedness. What should readers take away from your report?

Response: There are clear differences in astigmatism between groups of people, and it’s not clear why. We have speculations as to why these trends exist, but because we looked at a general population, it is difficult to extrapolate these results to individual people. However, it is useful for a cataract surgeon to know that, for instance, women tend to have more WTR astigmatism than men and tend to have it for longer during their lives.  This could affect  surgical planning for patients receiving cataract surgery. What recommendations do you have for future research as a result of this work?

Response: We hope that this study will shed some light into trends of astigmatism and ultimately help ophthalmologists and vision researchers to optimize results for patients getting cataract surgery.

Thank you for the opportunity to present my research!


Characterizing Astigmatism in the U.S. Population 

AAO 2019 Abstract

Sumayya Ahmad, MD,Assistant Professor of Ophthalmology at the Icahn School of Medicine at Mount Sinai

9am Saturday – 1pm Tuesday, Poster 0335, Location E-poster and video terminals
Purpose-To identify demographic associations with astigmatism in the United States.
Methods-Keratometry and demographic data from the National Health and Nutrition Examination Survey (NHANES) from 1999-2008 was analyzed using multinomial logistic regression and adjusted for confounders.
Results-With-the-rule (WTR) astigmatism decreased with age: a 20-24 year old had a 20 times higher odds of having WTR astigmatism than an 80-85 year old. Females (39%), Mexican Americans (79%) and college graduates (48%) had higher odds for having WTR compared to males and non-Hispanic whites with less than a ninth grade education. Myopes with >1.5 D sphere had a 53% higher chance of ATR than emmetropes Higher degrees of astigmatism (>1.5 D) was 48% more common in WTR patients than in ATR.
Conclusion-There is a significantly higher odds of having WTR astigmatism with younger age, myopia, having lower educational status and being female. These findings require further study for mechanistic insight. is not a forum for the exchange of personal medical information, advice or the promotion of self-destructive behavior (e.g., eating disorders, suicide). While you may freely discuss your troubles, you should not look to the Website for information or advice on such topics. Instead, we recommend that you talk in person with a trusted medical professional.

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Last Updated on October 14, 2019 by Marie Benz MD FAAD