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ARTICLES
Year : 1983  |  Volume : 31  |  Issue : 3  |  Page : 124-128

Low vision aids developed by intermediate technology and its specific role in the management of macular diseases


Dr. Rajendra Prasad Centre. for Ophthalmic Sciences, A.I.I.M S., New Delhi-110029, India

Correspondence Address:
Vijay K Dada
Dr. Rajendra Prasad Centre. for Ophthalmic Sciences, A.I.I.M S., New Delhi-110029
India
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Source of Support: None, Conflict of Interest: None


PMID: 6676195

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How to cite this article:
Dada VK, Acharjee SC. Low vision aids developed by intermediate technology and its specific role in the management of macular diseases. Indian J Ophthalmol 1983;31:124-8

How to cite this URL:
Dada VK, Acharjee SC. Low vision aids developed by intermediate technology and its specific role in the management of macular diseases. Indian J Ophthalmol [serial online] 1983 [cited 2024 Mar 29];31:124-8. Available from: https://journals.lww.com/ijo/pages/default.aspx/text.asp?1983/31/3/124/29764

Table 8

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Table 7

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Table 5

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Table 4

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Table 3

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Table 2

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Table 1

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Table 1

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  Introduction Top


Healthy macula is essential for the acuity of vision. In an emmetropic eye simple recording of vision indicates the state of the macula and in fact this is the most common test for macular function. With the invention of fluorescein angiography and argon laser photocoagulation management of macular diseases have become much more easier than before. Inspite of best possible treatment vision may remain grossly impaired in some cases making the persons visually handicapped. In such cases conven­tional spectacles are of little help.

The present study was undertaken to assess and improve the residual vision of the disabled cases scientifically with Low Vision Aids (LVA) developed by intermediate technology in India.


  Material and Methods Top


Sixty cases (117 eyes) of macular dysfunction were included in this study. Cases were refered to our Low Vision Aid Clinic and Research cell from the O.P.D. and speciality clinics of Dr. Rajendra Prasad Centre fo r Ophthalmic Sciences as wait as from various states and neighbouring countries.

A detailed Low Vision history was recorded under the following heads:­

i) Age of onset

ii) Progress of the diseasc

iii) Education

iv) Medication-present and past

v) General Health

vi) Occupation-past, present and future

vii) Surgery done, if any.

Visual status for distance was noted with special refrence to:­

i) Travel out door with/without guide

ii) Travel indoor with/without guide

iii) Tolerance to light

iv) Street sign/Bus sign

v) State of olfaction, auditory and kinesthetic senses.

Visual status for intermediate distance:­

i) Ability to read type written material

ii) Machine tools

iii) Sewing

iv) Musical instruments

Visual status for near:­

i) Newspaper head line

ii) Medium size print

iii) Mail

iv) News print

Light requirement:­

i) Bright

ii) Medium

iii) Dull

iv) Bright light improves or deterioriates?

Visual acuity was recorded for near and distance separately with and without glasses. Refraction was done. Fundus was examined to note the extent of mor­phological damage of the macula. Any other associated ocular findings were also recorded.

The cases were then subjected to low vision test with a series of optical gadgets fabricated in our research cell. The aids were:­

i) Indian telescopes (Gallilean) x2, x4

ii) Fixed focus stand magnifiers x2.5-x5

iii) Variable focus stand magnifiers x2.5-x5

iv) Visolett x2.5

v) Half cylindrical rod magnifier x2

vi) Hand magnifiers x2.5-x5

vii) Folding magnifiers x2.5-x5

viii) High plus spectacle magnifiers xl-x5

ix) Half eye spectacle-Prism glasses xl-x2.5

x) Microscopic spectacles x6-x10

xi) Clip on magnifiers xl.5-x5


  Results Top


Out of 60 cases (117 eyes) included in this study 45 were males and remaining 15 cases were females [Table - 1]. They came from India and other-neighbouring countries [Table - 2].

Educational background of the cases varied from illiterate to the postgraduate level [Table - 3]. Age of onset of the visual impairment has been highlighted [Table - 4]. Types of macular lesions were classified as described by Ballantyne & Michelson (1970) [Table - 5]. Visual improvement with various optical aids were noted separately for distance and near [Table - 6],[Table - 7][Table - 8]. It is worth mentioning here that in 52 out of 60 cases near vision could be improved only with single vision high plus spectacle magnifiers. The power of the glasses varied from + 4D to + 40D. These cases improved with other magnifiers also. We could improve near vision in 108 eyes. Similarly improvement of distant vision with x2 and x4 Gallilean telescopes was also remarkable [Table - 7]. Out of 117 eyes distant vision improved in 107 eyes. Remaining showed no improve­ment with the aids used due to extensive patho­logy and resultant gross deterioration of vision. Because of strong motivation children and young adults makes the best L.V.A. patient. In addition their large accommodation reserve allows them to read by holding the material close to the eyes. These cases improved best with the spectacle magnifiers. Elderly paitents mostly preferred hand held magnifiers.


  Discussion Top


Low vision examination is a tedious proce­dure which requires longer time, more co-ope­ration by the patient and more patience on the part of the examiner. The ophthalmologists have to discard the conventional ideas about refractive results as in prescribing low vision aids. Subjective improvement with no objective confirmation is the usual methodology.

In macular pathology main concern of the patient is his visual loss. We found that most of the cases were psychologically disturbed, worrying about their social, emotional and vocational problems. Because of the loss of central vision many patients feared that they are going to become blind very shortly. They need­ed detailed explanation of the disease process and constant reassurance by the ophthalmolo­gist. Due to the central scotoma they were severely handicapped for nearwork though their mobility was not much restricted because of good peripheral field of vision.

Few of our elderly cases were already using hand glasses purchased from market. With L.V.A. near vision improved in 108 eyes. The optical aids for reading are based on the simple principle that the retinal image increases in size as the object is brought close to the eye. The function of such device is to permit the object to be visualised from a short distance without making excessive demand upon accommoda­tion. It is important to prescribe the minimal magnification required by a particular patient because of limitation of field, decrease in work­ing distance, distortion and other aberrations which accompany high magnification. The latter can be avoided by using aspheric lenses. Near vision telescopes help in increasing the working distance. As mentioned earlier in 52 out of 60 cases near vision remarkably improv­ed only with single vision high plus spectacle magnifiers.

Distant vision could be improved in 107 eyes by using x2 and x4 gallilean telescopes. In gallilean telescopic system a parallel bundle of rays from the object incident on the objective, after refraction emerges from the eyepiece as magnified parallel bundle of rays and enter the viewers eye. Thus a telescope magnifies the object and brings it nearer.

The light requirement varies from person to person. Ideal illumination is determined by patients requirement in relation to the ocular disorder, the object and work to be performed. Light must be direct, of sufficient intensity and introduced at such an angle to avoid glare. Older patients needs greater illumination.

Initially many patients find it difficult to locate the object and focus with the aids. But gradually with strong motivation and reassur­ance they learn the art. We had to call many cases in the clinic repeatedly for practising L.V.A. till the final prescriptions were given up to their satisfaction.


  Conclusion Top


From this study we conclude that:­

1. Older the age more is the acceptance for the hand magnifiers.

2. Younger the age more is the likness for the spectacle magnifier.

3. More the loss of vision more is the acceptance for the hand held magnifiers.

4. Lesser the visual impairment more is the acceptance of spectacle magnifiers.

5. Though distant vision improved with telescopes only a few accepted it because of the limited field and cosmetic reasons. Telescopes are particularly useful for student to read the black board.

6. Lastly a careful low vision history, moti­vation of the patient, reassurance by the exami­ner, proper magnification and the illumination factors are the key points in successful dealing of such cases.


  Summary Top


117 eyes of 60 visually handicapped cases having various types of macular pathology were evaluated and improvement of their resi­dual vision were tried by locally fabricated low vision aids. To our surprise it was found that in 52 out of 60 cases near vision could be gain­fully improved only with single vision high plus spectacles magnifiers. These cases also improved with other magnifiers.

Vision improved both for near and distance in 105 eyes, 3 eyes showed improvement only for near and 2 eyes only for distance. 7 eyes showed no improvement due to extensive dam­age and consequent gross diminution of vision. All cases of macular diseases, whether suitable for active treatment or not should be strongly considered for L.V.A. assessment and possible improvement of their residual vision.



 
 
    Tables

  [Table - 1], [Table - 2], [Table - 3], [Table - 4], [Table - 5], [Table - 6], [Table - 7], [Table - 8]



 

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  In this article
Introduction
Material and Methods
Results
Discussion
Conclusion
Summary
Article Tables

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