At first, it felt like something was in her eye. Then her eyes turned red, watery and irritated. Her vision became blurry, and she found it difficult to read. It was painful to fly, and to be in air conditioning. Ilene Gipson, a scientist who studies eye disorders, didn't need a specialist to tell her what she had. "I knew what it was," she says.
Gipson had dry eye disease, an ailment that occurs when the eye does not produce enough tears, or when the tears evaporate too quickly. It is the most common eye problem that older women experience, and it disproportionately affects women: more than 3 million women vs. about 1.7 million men, according to the American Academy of Ophthalmology.
And it's not the only one. Many eye disorders — some of them quite serious — seem to favor women over men.
"Women make up two-thirds of the people who are visually impaired or blind in the world," says Janine Clayton, an ophthalmologist who heads the office of research on women's health at the National Institutes of Health. "Most people would say, 'That can't be the case in the United States.' But it is. Unfortunately, we don't know why."
Blindness or vision impairment can disrupt quality of life, affecting the ability to work, travel, care for one's family, live independently and stay socially active. An estimated 2.7 million American women older than 40 have low vision or are blind, according to NIH's National Eye Institute (NEI). Yet an estimated three-quarters of cases are preventable or correctable, according to Women's Eye Health, an educational organization of eye disease researchers.
Women are especially prone to dry eye disease, age-related macular degeneration (AMD), glaucoma, cataracts and Fuchs corneal endothelial dystrophy, in which a layer of cells on the inner part of the cornea die, causing vision to become cloudy or hazy. All except dry eye can lead to blindness or low vision.
Women with diabetes face an elevated risk of developing eye problems, among them diabetic retinopathy, which causes the blood vessels in the retina to bleed or leak fluid. Pregnancy also can prompt eye complications, such as temporary swelling of the cornea, a condition that results from increased fluid in the body.
Experts don't know why women seem to be more vulnerable than men to eye disorders. They speculate hormones are involved because many eye diseases occur after menopause, dry eye in particular. But there is no evidence that shows a link.
"Hormones probably play a role somewhere in this incredibly complex interconnection of molecules that we may never find," says Gipson, who studies ocular surface diseases at Harvard's Schepens Eye Research Institute. "But to try to sort it out is mind-numbing."
Clayton agrees, noting that the female hormone "estrogen is protective of the optic nerve," although "it doesn't prevent dry eye," and women who take post-menopausal hormones still experience a high rate of dry eye, she says.
Experts point out that one reason women seem to suffer these disorders in larger numbers than men probably has to do with longevity. Women live longer than men, and many eye diseases occur in older people. In the United States in 2010, for example, 65 percent of AMD cases were in women, compared with 35 percent in men, according to the NEI. AMD causes damage to the macula, a small spot near the center of the retina that is needed for sharp, central vision.
Still, even adjusting for age still leaves more women than men suffering from AMD.
"The numbers [for AMD] are huge for women," says Emily Chew, deputy clinical director at the NEI and the primary investigator in studies that found taking certain combinations of vitamins slows the progression of AMD. "Even if you adjust for age, you still see a larger number of women."
These vitamin combinations are formulated specifically for this purpose and are available over-the-counter. However, experts recommend that people take them only if their eye doctor recommends it.
While the hormone connection remains murky, other research indicates that exercising, eating a healthy diet and shunning smoking can help prevent certain eye problems and that genes and vitamin D deficiency also may play a role. Several studies looking at the impact of diet and exercise on AMD have found that women who regularly worked out, didn't smoke, and ate lots of leafy green and orange vegetables, fruit, dairy, grains and legumes lowered their risk, while having a genetic predisposition raised it.
There is also evidence that consuming fish full of omega-3 fatty acids — salmon and tuna, for example — at least three times a week is protective against certain eye diseases. (Pregnant women are advised that exposure to mercury, which is present in certain fish, can harm a developing fetus.)
Experts think women's eye problems may have some relationship to autoimmune diseases, which also overwhelmingly strike women. Inflammation, a hallmark of autoimmune disorders, also shows up in many of these eye conditions. One autoimmune disease, in fact, Sjogren's syndrome, is characterized by dryness of the mouth and the eyes, often severe.
"The fact that women are very much more susceptible to autoimmune diseases and dry eye may mean they are more likely than men to develop inflammation in response to eye injury — for example, drying of the surface of the eye," Gipson says.
Dry eye disease "is the most common [eye] problem that older women experience," says Rachel Bishop, chief of the NEI's consult services section. "Most eye doctors regard it as a nuisance condition. Dry eye merits a work-up that it usually doesn't get. Because it's not something that causes blindness or something a doctor can take to surgery, it doesn't always get the attention it deserves. But it's not just a nuisance condition. It's not as simple as it sounds."
Dry eye disease can be debilitating, according to Clayton of the women's health research office at the National Institutes of Health. "The cost of treating dry eye annually in the United States is $3.84 billion, including prescription drugs," she says. "If you account for people not working, that number goes up to $55 billion."
It can be treated — but not cured — by using artificial tears or stronger prescription drops. Sunglasses that have side shields to block wind and dry air can reduce symptoms in windy or dry conditions.
"This is not a minor thing for people who have it," Clayton says. "It makes you light-sensitive and affects your ability to work at a computer. You blink a lot. You have to take more breaks. You don't want to go to movies where you have to read subtitles. Because the wind dries out your eyes, you can't tolerate leisure activities. Doctors often don't take it seriously, but it's a real disease that causes a real impact."
Gipson agrees. She was lucky. Her dry eye disease resolved on its own several years ago, although she doesn't know why. This is unusual, as it is typically chronic.
"During the period I had it, I couldn't go into an arid environment," she recalls. "Flying was so painful, I had to sit with a wet cloth over my face. I'm also a birdwatcher, and I had to wear goggles with a moisture component to go birdwatching. I used [over-the-counter] ointments to protect the surface of my eyes when I went to bed, which makes you bleary-eyed, so you can't do it during the day. I thought I would have to live with it for the rest of my life."
Women, older women in particular, should never ignore their eyes — although many do, experts say. Too often, they are so busy caring for others that "they tend to take care of themselves last," Clayton says. A thorough annual eye exam for women is no less important than a mammogram or Pap smear, she adds.
"Eyes indicate overall general health," Clayton says. "The eye is part of your entire body. It's not a separate system. Diseases that affect your body — high blood pressure, for example — can show up in your eye. An ophthalmologist can diagnose a disease you didn't know you had by examining your eyes. A trip to the [eye] doctor not only could save your eyes, but your life."