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LOW VISION

Cataracts




magnifying the object makes it easier to see

hand-held illumnated magnifiers



hand-held magnifiers

closed circuit television



For use with two eyes

For use with two eyes

hand-held magnifiers











hand-held illumnated magnifiers



hand-held magnifiers

closed circuit television



For use with two eyes

For use with two eyes

hand-held magnifiers










 THIS PAGE

This page is intentionally enlarged to make it easier for the visually impaired.

 WHAT IS LOW VISION

Surveys have consistently shown that most people do not know what low vision is. Low vision is often described as a visual impairment which causes a difficulty in seeing despite the use of spectacles or contact lenses. Its presence may be noticed only when someone is unable to see well enough to do the things they used to be able to do.

Low vision is usually considered to be eyesight which cannot be corrected with normal spectacle or contact lenses to the usual standard of what is termed 20/20 or 6/6. Low vision is often referred to as impaired vision or partial sight and it can often mean that there is a distortion of vision or that parts of the vision may be missing. A person with low vision is someone who has an untreatable impairment of visual function which causes a restriction to normal activity. The problem of low vision may be overcome by using lenses which make objects appear to be larger than they really are. Enlarging objects make them easier to see as shown in the animation below.

Magnifying the object makes it easier to see

 SIGHT IS PRECIOUS

Sight is one of our most precious senses. In the world now, there are about 45 million blind people. Yet 80% of world blindness can be prevented or cured. In the UK approximately 120 people lose their sight every day. Many more have deteriorating vision which can be helped with the appropriate vision appliance.

 LOW VISION IN CHILDREN

It is estimated that of all those blind worldwide 3% are children and that 1.25 million children are blind. Most areas of the world have seen a decrease in blindness except for Sub-Saharan Africa where an increase in the population is thought to be responsible. The main causes are corneal scarring (clouding of the front window of the eye), cataract, glaucoma and retinopathy of prematurity

Children can inherit conditions such as retinitis pigmentosa which predominantly affects the side vision, macular dystrophies which prevent central detailed vision and Leiber's optic atrophy which affects the whole of the visual area.

Children can also suffer from retinal detachments and older children can lose vision from diabetes.

 MANAGEMENT

The most effective method of managing low vision is by means of magnification. Vision may seem blurry or distorted but magnifying the size of the image can enable the object to be seen more easily as shown above.

 LOW VISION AIDS

D & J Brower Opticians can supply virtually any low vision aid from all the well known brands such as Peak, Specwell, Noir medical Technologies, Eschenbach and Coil usually through specialist supplier Edward Marcus who have been established since 1945. The Kindle from Amazon can be used as a low vision aid as the size of words can be increased to what is referred to as N40 which is about 5 times larger than normal newsprint.

 LOW VISION APPLIANCES FOR CHILDREN

Children get on better with LVAs if given them from about three years of age especially when explained how much fun they can be. Looking at comics with a bright mag or lobster pot magnifier can be a good starting point leaving a distance telescope to a later time. Regular visits are important as a child's ability develops.

 MOBILITY FOR THOSE WITH SIGHT LOSS

If you have difficuly moving around safely there is a great risk that as a result you may suffer a loss of independence but there are "mobility officers" available at Social Services to help you. People with loss of side or peripheral vision have more trouble negotiating their way past obstacles than those with just central vision loss and of the two million UK residents with sight loss only 5,000 have a guide dog and only 10% use a white stick or more correctly called cane. There are three types of white cane which is internationally recognised as a symbol of visual impairment. The "symbol cane" informs others that the user is visually less able, the "guide cane"is used primarily to locate steps or kerbs and the "long cane"is used to help people find their way and detect obstacles. More information is available from the RNIB at www.rnib.org.uk.

 QUALIFIED

Jennifer Brower runs a low vision clinic in Croxley Green having worked in the Hospital Eye Service for many years. She holds the Association of British Dispensing Opticians' Honours Diploma in Low Visual Acuity and is a course examiner.

CAUSES OF LOW VISION

The four most common causes of blindness in the UK are age-related macular degeneration, cataracts, diabetes and glaucoma.

AGE-RELATED MACULAR
DEGENERATION (AMD)

Age-related macular degeneration, as its name suggests, affects mainly the elderly. There is no real cure although there are currently a number of research programmes investigating various possible methods of treating the condition.

The two most common forms of AMD are dry and wet, and both can lead to severe sight loss. The dry form of AMD has a gradual onset affecting vision more slowly but the wet form is more severe with a sudden loss of sight.

Dry AMD, the more common form, is identified by the collection of yellow, fatty deposits called drusen in the macula, the central part of the retina responsible for clear central vision.

Wet AMD occurs much less frequently, around 1 in 10 of all AMD cases. However, 90% of people who are registered blind with AMD, have wet AMD. It is also characterized by the collection of drusen and by the development of abnormal, leaky blood vessels in the macula. In advanced cases, scar tissue may form, causing irreversible blind spots.

Early detection of any form of AMD is crucial, because vision that becomes lost cannot be regained. Eye examinations at least every two years enable the optometrist (ophthalmic optician) to detect eye disease in its early stages and arrangements can then be made for appropriate referral for advice, treatment and support services.

CATARACTS

Cataracts are not the once feared eye condition they once were because cataracts can be successfully operated on in the majority of people. The operation can be carried out on people of any age and, in fact, the late Queen Mother had a cataract operation a few years ago when she was in her nineties.

DIABETES

Over a period of time diabetes can affect the back of the eyes and cause the blood vessels to burst and allow fluid out which can affect the vision.

GLAUCOMA

Glaucoma is a preventable eye condition but many thousands of people in the UK do not know they have glaucoma because they do not visit an optometrist regularly enough. By the time they do it is too late to prevent some loss of vision.

CAN YOU SEE THE BIGGER PICTURE?

If you are partially sighted, or you know someone who is, there are ways to increase the size of text and images viewed on a computer monitor.

 Outlook Express
To increase the font size in Outlook Express 5 click on Tools · Options · Read · Fonts · on font size choose Largest.

 Internet Explorer
To increase the text size in Internet Explorer click on Tools · Internet Options · General · Accessibility and tick 'Ignore font sizes specified on Web pages'.

 Magnifier
The monitor can be magnified by clicking on Start · Programs · Accessories · Accessibility Options · Magnifier.

 Program Lens
Program lens is a down loadable freeware program from www.abfsoftware.com which is worth trying.

 Text to Speech
Text to Speech software is available as a freeware program to download from www.readplease.com. Just follow the instructions.

DEFINITION OF BLINDNESS

1. The statutory definition 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".

In considering this matter there are two important points to be noticed, namely
i) the test is not whether the person is unable to pursue his ordinary occupation or any particular occupation, but whether he is too blind to perform any work for which eyesight is essential; and
ii) only the visual conditions are taken into account and other bodily or mental infirmities are disregarded.

2. The principal condition to be considered is the visual acuity (i.e. the best direct vision obtainable with each eye separately or both together, where both are present, as tested by Snellen's type with focus properly corrected), but regard must also be paid to the other conditions set out below.

3. The persons examined may be classified in three groups, as follows:

Group 1 · Below 3/60 Snellen
In general, a person with visual acuity below 3/60 Snellen may be regarded as blind. In many cases, however, it is desirable to test the vision at one metre and not to regard a person having acuity of 1/18 Snellen as blind unless there is also considerable restriction of the visual field. (Note: 1/18 indicates a slightly better acuity than 3/60, but as the standard test provides a line of letters which an eye possessed of full acuity should read at 18 metres, there is some convenience in specifying 1/18.)

Group 2 · 3/60 but below 6/60 Snellen
A person with visual acuity of 3/60 but less than 6/60 Snellen
(a) may be regarded as blind if the field of vision is considerably contracted but
(b) should not be regarded as blind if the visual defect is of long standing and is unaccompanied by any material contraction of the field of vision, e.g., in cases of congenital nystagmus, albinism, myopia, etc.

Group 3 · 6/60 Snellen or above
A person with a visual acuity of 6/60 Snellen or better should ordinarily not be regarded as blind. He may, however, be regarded as blind if the field of vision is markedly contracted in the greater part of its extent, and particularly if the contraction is in the lower part of the field; but a person suffering from homonymous or bitemporal hemianopia retaining central visual acuity of 6/18 or better is not to be regarded as blind.

Notes..
(a) The question whether a defect of vision is recent or of long standing has a special bearing on the certification of blindness. A person whose defect is recent is less able to adapt himself to his environment than is a person with the same visual acuity whose defect has been of long standing. This is specially applicable in relation to Group 2 and 3.

(b) Another factor of importance, particularly in relation to Group 2, is the age of the person at the onset of blindness. An old person with a recent failure of sight cannot adapt himself so readily as can a younger person with the same defect.

(c) On rare occasions cases will arise which are not precisely covered by the foregoing observations, and such cases must be dealt with according to the judgment of the certifying ophthalmic surgeon.

(d) In making recommendations about persons up to and including the age of 16, examining ophthalmologists should bear in mind that there are other factors which may influence local education authorities in their decision about the special educational treatment to be provided.


DEFINITION OF PARTIAL SIGHT

1. There is no statutory definition in the National Assistance Act, 1948, of partial sight, but the Department of Health has advised that a person who is not blind within the meaning of the Act of 1948 but who is, nevertheless, substantially and permanently handicapped by congenitally defective vision or in whose case illness or injury has caused defective vision of a substantial and permanently handicapping character is within the scope of the welfare services which the local authority are empowered to provide for blind persons · but this does not apply to other benefits specially enjoyed by the blind, e.g. Income Support.

2. The following criteria should be used as a general guide when determining whether a person falls within the scope of the welfare provisions for the partially sighted, as well as in recommending, where the person is under 16 years of age, the appropriate type of school for the particular child concerned:
    (i) for registration purposes and the provision of welfare services, those with visual acuity -
(a) 3/60 to 6/60 with full field;
(b) up to 6/24 with moderate contraction of the field, opacities in media, or aphakia;
(c) 6/18 or even better if there is a gross field defect, e.g. hemianopia, or there is marked contraction of the field as in pigmentary degeneration, glaucoma, etc.
    (ii) for children whose visual acuity will have a bearing on the appropriate methods of education -
(a)severe visual disabilities · to be educated in special schools by methods involving · 3/60 to 6/24 with glasses;
(b)visual impairment · to be educated at ordinary schools by special consideration · better than 6/24 with glasses.

Notes.
(a)Infants and young children with congenital anomalies including visual defects, unless obviously blind should be classed as partially sighted.
(b)At age four and over binocular corrected vision should be the criterion.
(c)All in (ii) (a) and (b) above should be re-examined every 12 months · or earlier if there is reason to suspect any worsening.



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