Dry eyes can cause misery but no tears
Dry-eye syndrome is not fatal and it only rarely leads to blindness.
But for more than 10 million older Americans, most of them women, dry eyes can be anything from annoying to life-wrecking.
The eyes feel gritty, scratchy, parched, as if they are being slowly sanded away. Perhaps because eyes have so many more nerves than other parts of the body, they can hurt so much that all a person wants to do is to crawl off in a corner and close them. Sunlight can make things even worse; so can wind. Wearing contact lenses can be impossible.
For psychologist Teri Rumpf, 55, of Newton, it sometimes gets so bad that "you can't open your eye because the lid sticks to the cornea," she said. "You kind of pry it open."
For Barbara Bamford, 47, of Andover, "it's like having something stuck in your eye all the time."
Dry eye is a condition in which there is a reduction in either the quality or quantity of tears, said Debra Schaumberg, director of ophthalmic epidemiology in the division of preventive medicine at Brigham and Women's Hospital and an assistant clinical scientist at the Schepens Eye Research Institute, both in Boston: "The function of tears," she said, "is to lubricate the ocular surface and keep it healthy."
Scientists now have a much better handle on the causes of dry eye, and there are also promising new drugs that are either already approved by the US Food and Drug Administration or are getting there -- a potential boon not just to folks with dry eye but to contact-lens manufacturers who want to maintain their large market. In addition to over-the-counter "artificial tears" that provide temporary relief, there are a number of other treatments for dry eye, including supplements of omega-3 fatty acids or eating fish such as tuna.
In a procedure called "punctal occlusion," a doctor inserts silicone plugs into the ducts near the corner of the eye by the nose to keep the tears from escaping. Some people have their ducts cauterized (surgically scarred) for more permanent relief. Others turn to thick, swimming-type goggles that enclose the eyes to keep air out. In rare cases, people have their eyelids sewn partly shut to keep moisture in.
But the most exciting advances are in new prescription drugs. One called Restasis reduces inflammation on the eye surface and is already on the market. Another drug, not yet approved, is diquafosol, designed to increase fluid volume on the surface of the eyeball. Anti-inflammatory drugs for dry eye are in the works. Finally, studies are underway on topical androgen eye drops made by
Tears are not just water but a complex filmy fluid consisting of three layers. The two most common forms of dry eye are the "aqueous-deficient" type in which there's not enough production of the watery middle layer of tears, and the "evaporative" type, in which there's not enough of the lipid (outer) layer of tears to avoid evaporation.
Autoimmune diseases such as lupus, rheumatoid arthritis or Sjogren's syndrome are the leading causes of the aqueous form, said David Sullivan, a senior scientist at Schepens. One reason women get almost three times the dry eye problems as men is that women get more autoimmune diseases.
In Sjogren's syndrome, for instance, which includes dry mouth as well as dry eyes, immune cells mistakenly attack the lacrimal and salivary glands, said Dr. Douglas Jabs, a professor of ophthalmology and medicine at Johns Hopkins University School of Medicine. This autoimmune damage eventually leads to destruction of the lacrimal glands and, thus, decreased production of the watery portion of tears.
But other factors are at play as well, said Sullivan of Schepens, most notably the hormone androgen, which is present in both men and women, but at higher levels in men. Both the lipid-making meibomian glands and the water-making lacrimal glands respond to androgens. With aging, both sexes make less androgen, but this is particularly pronounced in women because they have less androgen to start with.
Androgen has another role as well, damping down the immune system, including the inflammatory response. Women who are androgen-deficient thus face a double-whammy: They don't have enough androgen to make tears and they don't have androgen's soothing effect on inflammation in the lacrimal glands.
"Curiously, estrogen-replacement therapy does not help," said cell biologist Ilene Gipson, director of the Women's Eye Health Task Force at Schepens. In fact, it makes things worse, said Schaumberg of Brigham and Women's. Her research shows that women taking hormone-replacement therapy actually have an increased risk of dry eye, perhaps because estrogen may decrease the function of meibomian glands.
Judy Foreman is a freelance columnist who can be contacted at foreman@globe.com.
