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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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