The term "dry eye" can be a little confusing since one of the most common symptoms is excessive watering or tearing! It makes more sense, though, when you learn that the eye makes two different types of tears.
The first type, called lubricating tears, is produced slowly and steadily throughout the day. Lubricating tears contain a precise balance of mucous, water, oil, nutrient proteins, and antibodies that nourish and protect the front surface of the eye.
The second type of tear, called a reflex tear, does not have much lubricating value. Reflex tears serve as a kind of emergency response to flood the eye when it is suddenly irritated or injured. Reflex tears might occur when you get something in your eye, when you are cutting onions, when you cry, or when you accidentally scratch your eye. The reflex tears gush out in such large quantities that the tear drainage system cannot handle them all and they spill out onto your cheek. Still another cause of reflex tearing is irritation of the eye from lack of lubricating tears. If your eye is not producing enough lubricating tears, you have dry eye syndrome.
Symptoms of dry eye:
- Watery eyes
- The feeling that there is sand or grit in your eyes
- Burning sensation, worse in heated rooms or air conditioning
- Vision that becomes blurred after periods of reading, watching TV, or using a computer
Causes of dry eye:
- Aging can result in less oil production in the glands of the eyelids. Oil keeps tears from evaporating off the eye. Reduced oil production allows tears to evaporate too quickly, leaving the eye dry.
- Diseases including Connective Tissue Disorders (Rhematoid Arthritis, Systemic Lupis Erythematosus, Sjogren's Syndrome), Parkinson's and Diabetes
- Hormonal changes, especially after menopause
- Prescription medications: These include some high blood pressure medications, antihistamines, diuretics, antidepressants, anti-anxiety pills, sleeping pills and pain medications. Over-the-counter medications including some cold and allergy products, motion sickness remedies, and sleep aids can also cause dry eye.
- Hot dry or windy conditions: High altitude, air-conditioning and smoke can also cause dry eye.
- Reading, using a computer or watching TV
- Eye surgery: Some types of eye surgery, including LASIK can aggravate dry eye.
Diagnosing dry eye:
Your eye doctor can check for dry eye by examining your eyes with a bio-microscope, measuring your rate of tear production, and checking the amount of time it takes for tears to evaporate between blinks. The doctor can also check for pinpoint scratches on the front surface of the eye caused by dryness using special diagnostic dyes such as fluorescein or Rose Bengal.
Treatments for dry eye:
The most common treatment is the use of artificial teardrops, which help make up for the lack of natural lubricating tears. Artificial tear products come in liquid form, longer lasting gelform, and long-lasting ointment form. Many different brands of artificial tears are available over-the-counter. Some contain preservatives and some do not. Unpreserved tears may be recommended for people whose eyes are sensitive to preservatives. Artificial tears can generally be used as often as needed, from a few times per day to every few minutes. You should follow the regimen your doctor recommends. Ask for samples of several different brands of tears so you can determine which helps you the most.
When infection, inflammation of the eyelids, or clogged oil glands contributes to dry eye, special lid cleaning techniques or antibiotics may be recommended (see section on Blepharitis). It may also help to avoid hot, dry or windy environments or to humidify the air in your home or office.
Anti-inflammatory medications such as Restasis have been shown to be effective. See our section on Restasis for more information. Research on nutrients called fatty acids as a treatment for dry eye is ongoing.
Punctal occlusion is a medical treatment for dry eye that may enable your eyes to make better and longer use of the few lubricating tears they do produce.