WHAT IS DRY EYE DISEASE?
Some people do not have enough tears on the surface of their eye to lubricate the eye and keep it comfortable; this is known as dry eye disease. It is a common complaint among middle-aged and older adults, especially women, and can be a cause of great discomfort and frustration to its sufferers. Dry eye is one of the leading causes of visits to eye care professionals.
Technically, dry eye disease is a group of disorders of the tear film due to insufficient tear production or excessive tear-film evaporation. This can cause irritation and damage to the ocular surface, especially the cornea (the clear, dome-shaped tissue covering the iris and pupil), the conjunctiva, and the eyelids. The tear film is spread over the eye by blinking and makes the surface of the eye smooth and clear. The film consists of three layers: An oily layer, produced by the Meibomian glands, forms the outermost surface; this reduces evaporation of the tears. The middle, watery (aqueous) layer makes up most of the film; it is produced by the lacrimal glands and cleanses the eye by washing away foreign particles and irritants. The inner layer consists of mucus produced by the conjunctiva; it helps the tears adhere to the eye. There is no single cause of dry eye disease. Deficiencies can occur in any of the components of the tear film layers covering the front surface of the eye, due to defects in any of the glands synthesizing tear components (collectively called the lacrimal system). Meibomian gland dysfunction is a major factor. There appears to be an inflammatory component to dry eye syndrome.
Dry eye disease seldom leads to blindness; however, the condition causes lots of suffering and a diminished quality of life. It can also impair functional visual acuity, leading to a decreased ability to read and to drive, especially at night. Furthermore, it increases the risk of eye infection. As is the case with other diseases involving chronic pain, the constant pain of severe dry eye disease sometimes results in poorer psychological health.
Severe dry eye is sometimes caused by Sjögren’s syndrome, which is a chronic, multi-organ autoimmune disorder that also results in dry mouth and often arthritis. There are fewer than one million Sjögren’s syndrome cases in the US, but their symptoms are very serious, and the health of their eyes is at risk. These patients should be under close care by a specialist.
WHO IS AT RISK FOR DRY EYE DISEASE?
Tear production normally decreases as we age, because increased inflammatory and oxidative stresses alter the glands of the lacrimal system. Therefore, the risk of getting dry eye syndrome increases with age. The condition is extremely common in people over age 55 of both sexes. However, it is intrinsically two to three times more common in women than in men at any age.
WHY ARE WOMEN SO MUCH MORE SUSCEPTIBLE TO DRY EYE DISEASE?
Research is showing that androgens (male hormones) are good for lacrimal and Meibomian gland structure and function. Men have a greater supply of these hormones throughout life, although the levels decrease in both sexes as people get older. Menopause itself, or lack of estrogen, does not appear to be a factor in the greater prevalence of dry eye in older women. Recent research shows that hormone-replacement therapy makes dry eye worse, not better and that taking estrogen increases the risk of having the condition by 70 percent. Refractive surgery (such as LASIK) can cause dry eye in some people. Contact lenses often make it worse, and dry eye sufferers usually cannot wear contacts. The condition is also more common in people with allergies. A wide variety of common medications (both prescription and over-the-counter) can reduce tear secretion and cause dry eye; this list includes some diuretics, beta-blockers, antihistamines, sleeping pills, anti-anxiety drugs, and pain relievers. Be sure to tell your eye care professional if you are taking any of these medicines.
WHAT ARE THE SYMPTOMS OF DRY EYE DISEASE?
The symptoms of dry eye disease are persistently painful, stinging, burning, or itchy eyes. The sensation is often referred to as gritty or scratchy, and it often worsens as the day goes on. There may be stringy mucus in or around the eyes, eye irritation from smoke or wind, and difficulty wearing contact lenses. Patients with the most severe disease are at increased risk of developing corneal scarring or ulceration. Therefore, seek help from an eye care professional if your symptoms occur frequently or interfere with functioning because it is important to rule out corneal injury or infection.
WHAT CAN BE DONE TO HELP PREVENT OR MITIGATE DRY EYE?
Anything that may cause dryness, such as an overly warm, dry room, hairdryers, smoke, or wind, should be avoided by a person with dry eye. A humidifier in heated rooms may help. Eye makeup can worsen symptoms in some women. Many people with dry eye complain of scratchy eyes when they wake up; this symptom can be lessened by using an artificial tear ointment at bedtime. There is some preliminary research suggesting that frequently eating fatty fish (such as tuna or salmon) may help prevent dry eye disease.
WHAT TREATMENTS ARE AVAILABLE FOR DRY EYE DISEASE?
Artificial tears are the mainstay of treatment. Artificial tear solutions and ointments give some temporary relief, but do little to arrest or reverse any damaging conditions. Many brands are available without a prescription; for mild cases, try several to find the one you like best. The preservatives in some eye drops can irritate the eye; preservative-free artificial tears may be required. Some new artificial tear solutions are formulated to normalize the electrolyte balance while lubricating the ocular surface; these should help to minimize irritation.
Anti-inflammatory agents can help combat the inflammation associated with dry eye. Topical steroids are appropriate for short-term use but can cause serious side effects when they are used for a long time.
Tears constantly drain out of the eye, through a small channel, into the nose. Your eye care professional may decide to close these channels either temporarily or permanently to keep tears on the surface of the eye. For some forms of dry eye disease, tiny plugs in these channels (a procedure called punctal occlusion) can boost tears by slowing the rate of drainage from the eye. A laser is sometimes used instead and can be effective.