Dry Eye Syndrome
Dry eye syndrome is one of the most common problems treated by eye physicians. It is usually caused by a problem with the quantity or quality of the tear film that serves to lubricate and protect the eye.
Tears are composed of three layers. The innermost layer is the mucous layer, which coats the cornea, forming a foundation so the tear film can adhere to the eye. The middle aqueous layer provides moisture and supplies oxygen and other important nutrients to the cornea. This layer is made up of 98 percent water along with small amounts of salt, proteins and other compounds. The outer lipid layer is an oily film that seals the tear film on the eye and helps prevent evaporation.
The different layers of the tear film are formed in several glands around the eye. With each blink, the eyelids spread the tears over the eye. Excess tears flow into two tiny drainage ducts in the corner of the eye by the nose. Theses ducts lead to tiny canals that connect to the nasal passage.
Dry eye syndrome has many causes. One of the most common reasons for dryness is simply the normal aging process. As people age, the tear film diminishes, and leaves the eye more exposed to the drying effects of air, wind and dust. Dry eye syndrome is rarely, however, caused by a complete lack of tear production. In fact, during dry eye episodes, the eye can still make enough tears that many patients complain of wet eyes and tearing. This occurs because the dryness causes the eye to produce more tears in an effort to replace the tear film.
Other common causes of dry eye symptoms include abnormalities in the production of the oily layer or mucoid layer of the tear film. Post-menopausal women in particular are commonly affected due to hormonal changes.
Blinking is very important for the normal maintenance of the tear film. When performing such activities as reading or working on a computer, we blink less frequently, allowing the tear film to evaporate.
Environmental factors such as hot, dry or windy climates, high altitudes, air-conditioning, cigarette smoke, dust and airborne particles may contribute to the symptoms of dry eyes. Contact lens wear may also worsen the symptoms because the contacts absorb the tear film.
Certain medications can also cause dryness, such as antihistamines, blood pressure medications, antidepressants, decongestants, and certain medications for Parkinson's disease. Sjogren's disease, thyroid conditions, vitamin A deficiency, and Parkinson's can also cause dryness.
When it comes to treating dry eyes, everyone's needs are a little different. Many find relief simply from using artificial tears on a regular basis. Some of these products are watery and alleviate the symptoms temporarily; others are thicker and adhere to the eye longer. Preservative-free tears are more expensive but are the most soothing and have fewer additives that could potentially irritate the eye. Avoid products that whiten the eyes.
Closing the opening of the tear drain in the eyelid with special inserts called punctal plugs is another option. This works like closing a sink drain with a stopper. These special plugs trap the tears on the eye, keeping it moist. This may be done on a temporary basis with dissolvable collagen plugs, or permanently with a silicone plug.
There are also simple lifestyle changes that can significantly improve the irritation from dry eyes. For example, drinking 8-10 glasses of water each day keeps the body hydrated and flushes impurities. Making a conscious effort to blink frequently, and taking breaks when reading or working on a computer is also helpful.
Recent evidence also suggests that ocular surface inflammation plays a role in dry eyes. In select patients, topical anti-inflammatory drops may be given for short periods of time. Dietary modification may also be used to create a noninflammatory diet. The products of omega-3 fatty acid metabolism include anti-inflammatory eicosanoids and thrombolytic agents. Omega-3 fatty acids also help to inhibit platelet aggregation, reducing the risk of stroke and heart attack. They may be found in flaxseed oil, olive oil, and fish oils (particularly fatty fishes like salmon and tuna) and are a major ingredient in HydroEye, a vitamin shown to improve dry eye signs and symptoms.
