Word blindness Health Dictionary

The statutory de?nition – for the purposes of registration as a blind person under the National Assistance Act 1948 – is that the person is ‘so blind as to be unable to perform any work for which eyesight is essential’. Generally this is vision worse than 6/60 in the better eye, or with better acuity than this but where ‘the ?eld of vision is markedly contracted in the greater part of its extent’. Partial sight has no statutory de?nition, but there are o?cial guidelines for registering a person as partially sighted: generally these are a corrected visual acuity of 3/ 60 or less in the better eye with some contraction of the peripheral ?eld, or better with gross ?eld defects. In the UK more than 100,000 people are registered as legally blind and some 50,000 as partially sighted. The World Health Organisation has estimated that there are over 40 million binocularly blind people in the world. The causes of blindness vary with age and degree of development of the country. In western society the commonest causes are glaucoma, diabetic retinopathy, other retinal diseases and senile cataract. (See also VISION.)

Any blind person, or his or her relatives, can obtain help and advice from the Royal National Institute for the Blind (www.rnib.org.uk).

Night blindness An inability to see in the dark. It can be associated with retinitis pigmentosa or vitamin A de?ciency (see EYE, DISORDERS OF).... blindness

See VISION – Defective colour vision.... colour blindness

See under BLINDNESS.... night blindness

Damage caused to the cornea of an unprotected EYE by the re?ection of the sun’s rays from snow. ULTRAVIOLET RAYS (UVR) are the damaging agent and people going out in snow and sunlight should wear protective goggles. The condition is painful but resolves if the eyes are covered with pads for a day or two. Prolonged exposure may seriously damage the cornea and impair vision.... snow blindness

A condition in which the patient sees better in a dim light or by night than in daylight. It is only found in conditions in which the light is very glaring, as in the desert and on snow, and is relieved by resting the retina (see EYE) – for example, by wearing coloured glasses for a time.... day blindness

See onchocerciasis.... river blindness

Inability to see at night or in imperfect light due to a deficiency of visual purple (rhodopsin) in the rods at the back of the eye due to low level Vitamin A. Night myopia usually affects people during twilight. “One in five people are not fit to drive at night.” May occur in glaucoma and other eye disorders. Other causes: old age, free radical damage.

Alfalfa tea freely.

Of value: Kelp, Irish Moss, Iceland Moss.

Diet. Vitamin A foods, carrots, bilberries, Cod Liver oil.

Supplements. Vitamin A, Beta-carotene. C (2g), E (400iu). B-complex, B2, Niacin, Zinc. ... eyes  - night blindness