Who gets dry eyes?
Dry eyes can affect anyone, but it becomes more common with increasing age. Dry eyes affects about 7 in 100 people in their 50s, and about 15 in 100 people in their 70s. Women are affected more often than men.
Understanding normal tears
Just above, and to the outer side, of each eye is a small gland called the lacrimal gland. This constantly makes a small amount of watery fluid which is the main part of the tears. When you blink the eyelid spreads the tears over the front of the eye to keep it moist.
Tiny glands in the eyelids (meibomian glands) make a small amount of lipid (fatty) liquid which covers the outer layer of the tear film. Cells at the front of the eye and inner part of the eyelids also make a small amount of liquid which adds to the tear film.
The tears then drain down small channels (canaliculi) on the inner side of the eye into a tear 'sac'. from here they flow down a channel called the tear duct (also called the naso-lacrimal duct) into the nose.
What are the causes of dry eyes?
Anything that reduces the normal amount of tears that you make may result in dry eyes. The causes include:
- Ageing. You tend to make less tears as you get older. In particular, some women notice dry eyes developing after the menopause.
- Medication. Some medicines which you may take for other conditions sometimes have a side-effect of causing dry eyes, or make dry eyes worse. These include: 医学全在线网站www.med126.com
- diuretics ('water tablets'); some antidepressants; antihistamines; some treatments for anxiety and other psychological problems; the contraceptive pill; beta-blockers such as propranolol, atenolol, etc; some eye drops used to treat other eye conditions.
This is not an exhaustive list. Tell you doctor if you suspect that a medicine is causing your dry eyes.
- Illness. Some people develop dry eyes as a symptom of a more general disease. For example, dry eyes may occur with rheumatoid arthritis, SLE (systemic lupus erythematosus), and Sjogren's syndrome.
- Damage to the outer part of the eyes, eyelids, etc, from disease, injury or surgery.
- Blepharitis (inflammation of the eyelids) is often associated with dry eyes.
- Unknown. Some younger people have no apparent cause for the reduced amount of tears and dry eyes.
What are the symptoms of dry eyes?
Both eyes are usually affected. The eyes may not actually feel 'dry'. Symptoms include:
- Irritation in the eyes. The eyes may feel gritty or burning. However, the eyes do not go red. If they do, another eye problem is usually present.
- Slight blurring of vision from time to time. However, dry eyes do not affect the seeing part of the eye, and dry eyes do not cause permanent damage to vision.
- You may not like bright lights.
- If you wear contact lenses, you may find they become uncomfortable.
Symptoms tend to be made worse by: windy weather which drys out the eyes further; tobacco smoke; low humidity; air-conditioning; when you blink less often, for example, when you read, or look at a computer screen or TV for long periods.
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