Severe to total loss of vision that cannot be rectified by corrective lenses
- Age, gender, genetics, and lifestyle as risk factors depend on the cause
Complete or almost complete loss of sight, usually termed blindness, affects at least 40 million people worldwide. Although most of those affected by this condition are in developing countries, more than 190,000 people in the UK are registered as blind, and many more are visually handicapped. The risk of becoming blind increases with age, but the condition can be present from birth (see Congenital blindness).
What are the causes?
Blindness may be caused by disorders of the eyes, the nerves that connect the eyes to the brain, or the areas of the brain that process visual information.
In developed countries, blindness is most often caused by a damaged retina due to macular degeneration or diabetic retinopathy, raised fluid pressure in the eye due to glaucoma, or clouding of the lens due to cataracts. Cataracts are also a common cause in developing countries, together with the eye infection trachoma and vitamin A deficiency (see Xerophthalmia).
What might be done?
Early diagnosis can help some underlying disorders that cause blindness to be treated to preserve vision. For example, if you have glaucoma, you will be given drugs to reduce the pressure in the eye (see Drugs for glaucoma).
If you are registered as blind or visually handicapped, you may be eligible for certain benefits and services. Visual aids, such as magnifying glasses, can make some daily tasks easier.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.