|Year : 1983 | Volume
| Issue : 5 | Page : 683-688
Teaching visually disabled
PA Lamba, Santosh Kumar, P D'Souza
Deptt. of Ophthal, Jawaharlal Institute of Post-Graduate Medical Education & Reseaarch, Pondicherry, India
P A Lamba
Deptt. of Ophthal, Jawaharlal Institute of Post-Graduate Medical Education & Reseaarch, Pondicherry
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Lamba P A, Kumar S, D'Souza P. Teaching visually disabled. Indian J Ophthalmol 1983;31:683-8
This presentation aims at bringing certain facts, methods and materials available to the aid of Visually Disabled, to the awareness of our fellow ophthalmologists and others involved in this field and stimulate their interest and generate a sense of challenge to involve themselves in this work.
The first step in the work to help Visually Disabled is to define and designate precisely the visual disablility.
A review of the official definition of blindness and partial sight reveals that different standards are in vogue in different countries [Table - 1].
We are at present following the U.S. standards but generalisations cannot be made in this field and each patient has to be individually assessed depending on the socioeconomic factors, level of education, professional requirements etc., For example a visual acuity of 6/36 may be a severe handicap to a skilled worker while it may not be a handicap to an unskilled worker.
Any action programme aimed at helping the visually disabled should span the entire spectrum of possible age groups. Ideally any teaching programme should commence in the paediatric age group and continue with necessary modifications throughout life.
The methods for helping children and adults vary widely due to the inherent differences of the needs and potentialities of these groups. We may therefore consider them separately.
| Visually disabled children|| |
There are several problems inherent to the categorisation of Visually Disabled children. It is quite difficult to make a proper assessment of visual acuity. In addition the most common affliction of this age group is congenital or hereditary disorders which may be associated with mental deficiency. These children may be grouped into:
I) Purely visually defective with normal intelligence. The only consideration in these children is the level of visual acuity.
II) Visually defective with associated defects such as deaf mutism which also have to be taken into consideration.
III) Visually defective with mental deficiency. Depending on the level of intelligence the child may have to be given vocational training only.
Countervailing these disadvantages however the children are more adaptable, more preserving and have greater capacity to learn.
| Teaching Methods|| |
Three types of educational plans are being used in the developed countries to teach the Visually Disabled children.
-Co-operative plan utilising special class room.
-Resource room plan.
-Itinerant teacher programme.
It is suggested that an ideal and inexpensive way of educating the Visually Disabled children in our conditions would be the provision of special rooms equipped with necessary aids in the ordinary schools so that these children can overcome their disability and at the same time avoid the psychological trauma of segregated schools. As a first step these schools may be established in major regional centres.
Visually Disabled Adults
Loss of vision or reduction to such a level as to render the person incapable of continuing in his vocation is a greater trauma socially, psychologically and economically, since this involves reorientation and reorganisation of the whole life of the individual. With the maximal use of low vision aids every effort should be made to enable the individual to continue in his present or closely allied vocation. Where this is not possible vocational rehabilitation by teaching a craft or art suitable to the individual should be provided, thereby restoring the self respect, and self confidence of the individual by making him financially independent and useful member of the community.
Regional co-operatives for the Visually Disabled should be encouraged to provide adequate facilities and incentives for these individuals.
The emphasis while evolving a teaching modality should be on the best possible utilization of the residual vision with the use of necessary aids.
For teaching the visually handicapped larger print (18 point-letter size approximately 3.3 mm high or 24 point, 4.0 mm high) is recommended by some workers since it provides 1.0 x and 2 x magnification respectively when held at the same distance [Figure - 1]. It is recommended by other workers that instead of large print the standard print (12 point letter size approximately 2 mm high) may be held closer to the eye provide magnification. For example standard print at 11 cms from the eye is of the same magnification as large (18 point) print at 20 cms. The disadvantage of large print is that the books become bulky and more expensive and the reading material is limited [Figure - 2]. Earlier concept that holding the reading material closer to the eye is damaging to vision has not been substantiated by subsequent investigations. The child may be encouraged to hold the printed material as close to the eye as is possible and necessary. Even if he can read the standard print at 5 cms from the eye either with or without special aids he must be encouraged to do so. The only indication for the recommendation of large print is when the choice is between printed material and braille.
Reading or learning braille has special psychological connotations since it has become synonymous with absolute blindness. Reading of print even at a reduced rate is better educationally, vocationally and socially. The disadvantages of braille are manifold; it is relatively slow process and an average reader attains a speed of only 90 words/mt, a page cannot be scanned while reading braille, lack of tactile sensitivity in fingers prohibits certain individuals from learning braille. Reading and educational materials as well as job opportunities are limited. Only situation for advocating the braille reading is when the visual acuity level precludes the usage of even Jaeger 13 or 18 point print at 5 cms from the eye aided by low vision aids or when there is gross field constriction rendering the reading of printed material extremely laborious.
Low Vision Aids or Optical Aids
These are usually lenses or system of lenses which improve visual acuity beyond that obtained with conventional spectacles. Most of these aids accomplish this by magnification and increased illuminations. Approximate magnification achieved by these appliances may be determined by dividing the dioptric power of the lens by 4. These appliances by their very nature impose certain limitations; shorter depth of focus, limited field, considerably shorter reading distance and cosmetically noticeable lens.
[Table - 2] and [Table - 3] give some of the conditions favourable and unfavourable for improvement of visual acuity with low Vision Aids (LVA) respectively. Classification of LVA is given in [Table - 4],[Table - 5].
Of the various designs available the Galilean telescopes [Figure - 3] are the most useful and commonly utilised. The telescopes based on the Galilean principle consists of a strong concave eye piece and weak convex objective separated by air. These telescopic spectacles have a limitation of a narrow field when used for distance. They are however more useful for near vision. The telescopic spectacles are of two types.
Full field: where eye piece alone is in front of the eye and provides a larger field. This may be binocular 1.6 and 2 x mafinificaton or monocular 3 x to 8x magnification.
Reduced aperture: In these telescopes the eye piece may be set into the conventional spectacles lens and decentred superiorly, may be binocular or monocular [Figure - 4] or the telescopic attachment may be clipped on to the conventional spectacles. It is binocular and is set below the datum line [Figure - 5]-'Bar type' with magnification of 2 x to 5 x are available. The reduced aperture telescope spectacles provide for the retention of any peripheral field.
The telescopic spectacles are designed with appropriate magnification for distance, near and intermediate distance use. The distance telescopic spectacles can be adapted for near use by a strong convex lens-'reading cap' mounted over the objective. The telescopic spectacles for near vision are now being manufactured in India [Figure - 6].
Hand held telescopes: Prism telescopes or commercially available telescopes dismantled and modified for macula r area by holding them in front of the eye [Figure - 7].
Tele bifocal spectacles: With distance and near visions segments are also available although of limited use.
Spectacles Magnifiers: Illuminated spectacle magnifiers for near vision where the reading material is held in contact with the spectacles with a magnifications of 8 x to 20 x are available [Figure - 8].
Non-spectacles Magnifiers: Hand magnifiers [Figure - 9] are probably the best LVA available to us. They are cheap, easily available and are simple to use. Appropriate strength biconvex lens allows a magnified view. If necessary illumination may be incorporated. The hand held magnifiers have to be held rigidly at a fixed distance from the printed material. In old age or when afflicted with tremor this may not be possible and these may be mounted on stands with or without illumination [Figure - 10].
The magnification lens may be incorporated into a paper weight which is placed of the printed material and pushed along the line [Figure - 11].
| Conclusion|| |
An attempt has been made to bring some facts regarding the Visually Disabled and the methods and materials to aid them to the awareness of our fellow ophthalmologists and others interested in this field.
| References|| |
Bier, N., Correction of subnormal vision, Butterworth & Co., 1970.
Fonda, G., Management of patient with sub normal vision, C.V. Mosby Company, 1965.
Abrams, D.. Duke Flder's Practice of refraction, Churchill Livingstonc, 1978.
Holt, L.B., Paediatric Ophthalmology Lea and Febiger, 1964.
Hirsch, M.J., and Wick R.E., Vision of the aging patient, Hammond and Hammond & Co., 1961.
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5], [Figure - 6], [Figure - 7], [Figure - 8], [Figure - 9], [Figure - 10], [Figure - 11], [Figure - 12]
[Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5]