Normally your eyes are kept moist by the tears that bathe the surface. The action of blinking spreads the tears across the surface of your eyes. Tears contain important substances that lubricate the eyes, prevent infection and slow down evaporation of the tears.
Dry eye can occur for several reasons - either because you do not make enough tears or because your tears evaporate too quickly. Symptoms can include irritation, gritty burning, inflamed eyes, resulting in ocular surface damage.
Dry eye is one of the most common of all eye conditions. Although it particularly affects older people, it can occur at any age. It is also more common in women.
What are the symptoms of dry eye?
Stinging, burning or a gritty feeling in your eyes are common symptoms. Your eyes may feel slightly red, feel heavy and become sensitive to bright light. Stringy mucus may collect on the lids. Symptoms may be less when you first wake up, but get worse as the day goes on.
Symptoms can be triggered by various situations. These include:
- Activities that make you blink less often, e.g. reading, driving, working at a computer monitor or watching television.
- Exposure to fumes, dust and cigarette smoke which can be particularly aggravating.
- Air-conditioning which can produce a dry atmosphere.
Fortunately, dry eye is unlikely to affect your sight. However, if your eyes are very dry, for example if you do not even produce tears in emotional situations or as a reaction to peeling onions, the symptoms may be intolerable.
What causes dry eye?
The most common cause of dry eye is a failure of the glands in your eyelids to produce tears, which often occurs as part of the ageing process. Blockage of the oil glands in the eyelids may worsen the problem.
Medicines used in the treatment of medical conditions, such as high blood pressure or kidney disease, can reduce the production of tears.
Less often, dry eye may be part of a medical condition, such as Sjögren's syndrome, which occurs in people with rheumatoid arthritis and other related conditions.