Dry Eye
Healthy eyes are continuously covered by fluid — a tear film designed to remain stable between blinks. A stable tear film prevents dry eyes and allows your eyes to maintain clear, comfortable vision.Decreased production of fluids from your tear glands can destabilize the tear film, allowing it to break down rapidly and create dry spots on the surface of your eyes. An imbalance in the substances that make up the tear film also causes dry eyes.
Dry eyes are a common source of discomfort. Treatment of dry eyes aims to restore a more normal tear film to minimize your dryness, blurred vision and discomfort.
Signs and symptoms of dry eyes, which usually affect both eyes, may include:
- A stinging, burning or scratchy sensation in your eyes
- Stringy mucus in or around your eyes
- Increased eye irritation from smoke or wind
- Eye fatigue after short periods of reading
- Sensitivity to light
- Difficulty wearing contact lenses
- Tearing
- Blurred vision, often worsening at the end of the day or after visually focusing for a prolonged period on a nearby task
For some people, the cause of dry eyes is an imbalance in the composition of their tears. Other people don't produce enough tears to keep their eyes comfortably lubricated. Eyelid problems, medications and other causes, such as environmental factors, also can lead to dry eyes.
Poor tear quality
The tear film has three basic layers: oil, water and mucus. Problems with any of these layers can cause dry eye symptoms.
Decreased tear production
Dry eyes are common, especially for people older than 40. Tear production tends to diminish as you get older. When you're unable to produce enough tears, your eyes become dry and easily irritated. The medical term for this condition is keratoconjunctivitis sicca.
Although dry eyes can affect both men and women at any age, the condition is more common among women, especially after menopause. This may be due in part to hormonal changes. Damage to the tear glands from inflammation or radiation can hamper tear production. Dry eyes are also associated with some medical conditions such as diabetes, rheumatoid arthritis, lupus, scleroderma, Sjogren's syndrome and vitamin A deficiency.
Refractive eye surgeries such as laser-assisted in-situ keratomileusis (LASIK) also may cause decreased tear production and dry eyes. Symptoms of dry eyes related to these procedures are usually temporary.
Poor lid function
Through blinking — normally at a rate of about once every 10 seconds — your eyelids spread a continuous thin film of tears across the surface of your eyes. Problems with your eyelids can impair the complex blinking motion required to spread these tears, resulting in dry eyes. Eyelid problems that may develop as you age include an out-turning of the lids (ectropion) or an in-turning of the lids (entropion).
Blepharitis, an inflammation along the edge of the eyelids, also may cause your eyes to feel dry and scratchy.
Medications
The types of common medications that can be the causes of dry eyes include:
- Diuretics, drugs commonly used to treat high blood pressure
- Angiotensin-converting enzyme (ACE) inhibitors used to treat high blood pressure
- Antihistamines and decongestants
- Sleeping pills
- Birth control pills
- Certain antidepressants
- Isotretinoin-type drugs for treatment of acne
- Opiate-based pain relievers, such as morphine
In addition, tasks that require intense visual concentration — such as working at a computer, driving or reading — tend to decrease your blink rate, thereby increasing tear evaporation.
Effective treatment for dry eyes begins with a careful examination to determine which factors may be causing your symptoms. The goal of treatment is to keep your eyes moist.
