dr claytonWe sometimes take our eyes for granted. They are so central to our well-being that many common phrases borrow sight-related metaphors: "Vision for the future," "Focus on what's important," "Keep your eyes on the prize."

As an ophthalmologist, I am especially attuned to the importance of this amazing organ, as well as the ability of eye health to be a barometer of general health. Eye changes, often only uncovered after a visit to an eye doctor, can signal the presence of many underlying conditions: high blood pressure, diabetes, cancer, and autoimmune diseases like lupus and rheumatoid arthritis.

Several years ago, an unusual experience with one of my patients revealed yet another surprising link. My patient was a young woman, yet her eyes looked very dry, like those of someone much older. Dry eye is a common symptom in older, post-menopausal women with declining estrogen levels.

As it turns out, my young patient's eye problems were a symptom of premature ovarian insufficiency, a disorder in women under 40 that is associated with fertility issues and other health problems. Her dry eyes were related to low estrogen levels. This new observation would set in motion new ideas about the role of hormones and health of the surface of the eye.¹

The case fascinated me. Beyond the effect of hormones, I wondered, were women's and men's eye disorders different in other ways? May 12-17 is National Women's Health Week and it is worth noting that two-thirds of people worldwide who are visually impaired or blind are female. You can learn more about the prevalence of eye disorders in women at Women's Eye Health.org .

As an investigator at the National Eye Institute, I was in a great position to learn more. Through a collaboration I initiated with NICHD investigators, we determined that some girls and women with the rare disease Turner syndrome — caused by a female's absence of one of her two X chromosomes — also report symptoms consistent with dry eye. I put together a clinical study to determine how many females with Turner syndrome have dry eye, compared to women with premature ovarian insufficiency and women without either condition.

The goal of this research is to see how dry eye is related to hormones, genetic effects, or both. What we learn should help us understand causes of dry eye and point to new ways to treat it in women and in men.

In my current position leading the NIH Office of Research on Women's Health, I am fortunate to be able to continue working in ophthalmology and investigating the connections between sex, gender, and ocular abnormalities. These and other projects underway are uncovering brand-new information about the role of sex as an important factor in the biology of human health.