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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 4 million older Americans with moderate to severe forms
of the condition, most of them women, and for 6 million more with
milder forms of the problem, 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. 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 says. “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 syndrome “is often pooh-poohed because it doesn’t usually cause blindness,” says Dr. Janine Smith, deputy clinical director of the National Eye Institute in Bethesda, Md. But it can destroy quality of life. “You have to blink all the time. You can’t keep your eyes open. If you have a job, it’s hard to do it.” “Dry
eye doesn’t kill anybody, but it can drive some people to want
to kill themselves,” adds Dr. Anthony Aldave, director of cornea
and refractive surgery at the Jules Stein Eye Institute at UCLA.
It can also make it impossible to wear contact lenses. But
scientists now have a much better handle on the causes of dry eye.
There are also promising new drugs that are either already
approved by the US Food and Drug Administration or getting there,
a potential boon not just to folks with dry eye but to contact
lens manufacturers who want to maintain their large market. Dry eye is a condition in which there is a reduction in either the quality or quantity of tears, says 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 is to lubricate the ocular surface and keep it healthy,” she says. Tears
are not just water, but a complex fluid consisting of three
layers. The bottom layer, closest to the eyeball, is called mucin,
which is made in three types of cells on the surface of the
eyeball. The watery, middle layer is made in lacrimal glands,
which lie under the eyebrow. And the outermost layer, made of
lipids, is made in the meibomian glands behind the upper and lower
eyelashes. The two
most common forms of dry eye are the “aqueous deficient” type
in which there’s not enough production of the watery layer, and
the “evaporative”
type, in which there’s not enough of the lipid (outer) layer to
keep tears from evaporating. A
leading cause of the aqueous form is auto-immune disease like
lupus, rheumatoid arthritis or Sjogren’s syndrome, says 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 auto-immune disease. In
Sjogren’s syndrome, for instance, which includes dry mouth as
well as dry eyes, immune cells mistakenly attack the lacrimal and
salivary glands, says Dr. Douglas Jabs, a professor of
ophthalmology and medicine at Johns Hopkins University School of
Medicine. This auto-immune 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, says 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,” notes cell
biologist Ilene Gipson, director of the Women’s Eye Health Task
Force at Schepens. In fact, it makes things worse, says 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. 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
like 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 Allergan of Irvine, CA, designed to combat the androgen deficiency of many cases of dry eye.
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