Year : 1967 | Volume
: 15 | Issue : 5 | Page : 181--188
Review of 700 cases seen in low vision aid clinic
Low Vision Aid Clinic, Eye Department, Erskine Hospital, Madurai, India
Low Vision Aid Clinic, Eye Department, Erskine Hospital, Madurai
|How to cite this article:|
Namperumalsamy P. Review of 700 cases seen in low vision aid clinic.Indian J Ophthalmol 1967;15:181-188
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Namperumalsamy P. Review of 700 cases seen in low vision aid clinic. Indian J Ophthalmol [serial online] 1967 [cited 2020 Jul 11 ];15:181-188
Available from: http://www.ijo.in/text.asp?1967/15/5/181/38804
The Low Vision Aid Clinic is attached to the Eye Department, Erskine Hospital, Madurai, which started functioning from November 1966. Cases seen are mainly from other clinics of the same department, i.e. Glaucoma Clinics, Neuro-Ophthalmology Clinic, Uveitis Clinic, etc. In addition, we have had cases referred by Ophthalmologists from various hospitals. It is interesting to note that patients have come from distances even 2,000 miles away, and we were able to help most of them.
During this period of 5 months from November 1966 to May 1967, we have examined about 869 cases. Out of these the present paper contains the data collected from the first 700 cases. [Table 1] shows the monthwise statement of the number of patients who attended the clinic and the percentage of improvement.
The establishment of Low Vision Aid Clinics in 20 countries speaks for the need in helping the partially sighted patient. In certain countries this type of clinics are well-developed and deal with innumerable devices suitable to the needs of the individual patients. In India, this clinic, being the first of its kind, is still in infant stage. The fact that there are about 5 million blind people and more of them who are not totally blind, would be having some residual vision which can be helped. A single clinic of this nature will not be able to meet the needs of all of them. As such India needs many more such clinics. [Table 2] shows the number of patients who attended from various places of India.
Low Vision AIDS
People who have vision less than 6/60 or even 6/36 are said to have low vision and these people will not be able to carry out the normal work as reading, writing, knitting, etc. All the blind people will not be totally blind and at least 50%, of them would be having some residual vision. Making use of the residual vision, however small it may be, we can make the patient read and rehabilitate. People who can go out-doors with their own subnormal vision, may be helped for reading by these low vision aids at suitable working distance. Reading at close distance is not harmful.
The principle of low vision aid is to make the eyes see by magnifying the images of the objects or by bringing the objects closer to the eye. By altering the illumination also we can help some patients. The amount of magnification needed for the patient depends upon the condition of the macula, para-macular area and other parts of the retina. When the field of vision is more limited, magnification by glasses will not be helpful, as, in cases of retinitis pigmentosa, glaucoma, etc.
Working plan of the clinic: Examination of a case of sub-normal vision, either for distance or for reading or for both is a time consuming and patience testing task. As soon as the patient comes in, a careful history is taken and the patient is asked to answer the following questions:
Questionnaire: Concerning diagnosis.
Duration of the Blindness, Educational background,
Can walk outdoor or indoors,
Tolerance in light,
Can read headlines of a newspaper but not small prints,
Can do his work,
Bright light or dim light is better,
Prescription of glasses if any or magnifiers used,
Each of them has got significance and a patient who has developed this subnormal vision recently would be expecting us to give him full normal vision as he enjoyed previously, or a patient who has not been using his residual vision at all would not be in a position to recognize the letters, etc. as he has not been oriented to this new environment, He would have been well trained in Braille and other systems and would feel better than with new glasses and their use.
Educational background also plays an important role in the treatment with these aids. A patient who has not been able to read for years due to his ailment, if he is made to read the prints, he will be much satisfied and would feel grateful. But when an illiterate villager comes for such aids, his aim is to get his normal vision to earn his living and we could not help him. So, as son as the patient comes in, it is better to know the particular need of the patient rather than wasting the time.
People who can go outdoors without hitting against anything or falling down can be definitely helped by these aids. This shows that they have fairly good field of vision. People who have tubular vision as in retinitis pigmentosa, glaucoma, optic atrophy, may not walk so freely and so in these cases the results of treatment are not favourable.
Alteration of illumination will bring favourable results in some cases depending upon the individual tolerance of light and the nature of the disease. Cases of macular choroiditis will feel better with dim light. Optic atrophy cases need bright light. In posterior cortical cataract, as all the ophthalmologists are aware of, the vision lost is out of proportion to the amount of cataract present because of the central position of the cataract occupying the nodal point. As the periphery of the lens is clear, when the pupil is dilated by means of mydriatics, they see better. Moreover these patients see better before sun-rise and after sun-set, i.e. in dim light. So by suitable adjustment of light, they can be given relief at least until the time they can get operated.
We have to find out whether the patient is motivated for using these aids or they are forced to use them by his parents or relatives. Since most of these appliances need much practice and patience before they could be used successfully, it is important that patients must co-operate and work hard to get used to these glasses. It is noted that younger individuals are well motivated than older people. This may be due to the fact that the aged cannot keep the printed matters steady and there may be tremors of the, hand and nodding of the head. Older people will take it as pastime but for the younger individuals it is life-long affair.
Outline of Study
The report presented here represents data on 700 cases seen in, the Low Vision Aid Clinic from Nov. 1966 to March 1967 and illustrates the type of patient, the amount of visual acuity and visual need, and the particular eye pathology which need the low vision aids.
Selection of Patients to Low Vision Aid Clinic
It is important to note that patients who have been blind for many years will naturally desire to regain the vision partially, if not fully and it is worthwhile to remember that these aids are just to help them to utilise whatever amount of vision they have and not possible to get back their original vision. So selection of patients of low vision who need these aids becomes a difficult job. Where efforts to improve vision with medical and surgical means have failed, it is the function of the clinic to make such patients utilise their subnormal vision.
Data includes analysis of the 700 cases according to the causes of low vision and whether improved or not improved. The result is noted as improved when the patient is able to read newsprint now, as compared to previously when he was not able to read even headlines. Improvement may be for distant vision and near vision or for near vision alone. Almost all cases improved with telescopic lenses but these glasses could not be used always because of limited field of vision and motion parallax it produces when it is used by patients for outdoor use.
Each case was examined thoroughly and results were noted. The routine examination was
(1) Routine refraction including keratometry, retinoscopy, etc.
(2) Refraction with telescope-Telescope in the trial frame with subjective trial lenses in the posterior cell of the trial frame.
(3) If distant vision is improved, near vision with high plus lenses suitable to his job, reading, etc. If distant vision is very poor, trial with microscopic lenses.
(4) Trial with hand magnifier in selected cases.
The distant vision charts are fixed at 3 meters instead of normal 6 meters distance and the charts also are of special type having letters ranging from 20/200, 20/175, 20/155, etc. instead of usual 20/200, 20/120, etc. to assess the correct visual acuity. The magnification required for near vision is calculated from distant visual acuity or near vision acuity.
Out of 700 cases examined 43 cases were not completed since some of them did not turn up after the first visit.
Some patients were not satisfied as their intention was to get back their original vision. From [Table 3] one could easily find out that out of 657 cases 490 cases have improved. Among them we have included some high myopia and aphakia in whom ordinary refraction could improve their vision to a slight extent, but with telescopic refraction, we, were able to improve their vision further. The incidence of choroiditis is included under the heading macular choroiditis.
Cataract: This analytical study indicates that cataract is the common cause for the visual handicap until the time it becomes suitable for operation. Out of 107 cases of cataract, 99 cases improved either for distant vision or for near vision or for both. In most of these cases ordinary refraction could not be done due to poor retinoscopic shadow and they were advised operation after sometime. With subjective trial with telescope, their vision improved for distance. For near vision about 50% were able to read without any aid. 30% of cases were given high plus glasses, ranging from +4.00 D. Sph. to+8.00 D. Sph. One patient was able to read even newsprint with + 18 hand magnifier. When cataract is associated with other general diseases like diabetes and hypertension, etc. need bigger magnification. Two cases of cataract associated with diabetes, were given +14 D. Sph. for reading.
Aphakia : 80 patients improved out of 97 cases tried. These patients were referred by other ophthalmologists. Some of them were associated with optic atrophy or some post-operative complications like corneal opacities, iris prolapse, etc. In some, retinoscopy could not be done because the pupils were drawn up. To quote one case who came for correction, had catacract in both eyes for which he underwent operation. He had adherent leucoma too. His vision was only 2/200 in his right eye and hand movements in his left eye. Refraction was done and he was prescribed glasses. For distance R.E.+ 15.00 sph-3.00 cyl @ 180°.
For reading he was prescribed X10 microscope. His vision improved upto 10/ 150 in his right eye and he could even read newsprint with microscopic glass which he has received from United States.
Glaucoma : Early cases of glaucoma, when the fields are not much affected, are suitable cases for low vision aid. The same applies to cases of retinitis pigmentosa and optic atrophy. 40 cases of glaucoma improved out of 53 cases. Most of them had normal or slightly affected peripheral fields and controlled tension. Only 60% of cases of retinitis pigmentosa improved. The failure is due to tubular vision and magnification in these cases will not be helpful as it will further reduce the field of vision. A lady, aged 31 years, had chronic simple glaucoma. Her vision in the right eye was no P.L. and LE 6/175. Her field was slightly restricted. She improved upto 10/60 with -7.00 Sph. -4.00 cyl @ 90° in her left eye.
Optic Atrophy : Out of 57 cases improvement was noted only in 22 cases. Most of them improved only for near vision and the patients were able to read with the low vision aid. The microscopic lenses were found to be the type of aid suitable for these cases.
Macular Choroiditis: Under this heading we have included other forms of choroiditis also involving the macula. The magnification will be helpful only when the para-macular area of the retina is little affected or normal. They will feel better when the illumination is not very bright. It is obvious from [Table 3] that cases of macular choroiditis improved to a greater extent than in any other disease. Out of 41 cases, 33 have received the low vision aid and proved to be successful. One patient aged 58 years was able to read even the newsprint with +5.5 D. Sph. in dim illumination. He was found to , be a case of macular choroiditis. He has been prescribed glasses with tint. Some people with congenital macular degeneration and senile macular degeneration improved with magnification. They were prescribed telescopic lenses for distant vision. It is our experience that in some cases of macular choroiditis we were not able to help them because the macula and the para-macular area were so affected that the patients were not able to fix and they had nystagmus too.
[Table 3] also shows the incidence of various diseases causing low vision according to the age group. It is found from the statistics that more than 50% were above the age of 40 years. This can be attributed to the incidence of cataract, occurrence of general diseases like diabetes and hypertension in elderly age group. The age is an important factor which is to be considered in fitting a low vision aid. An old patient who has not been used to reading for many years may not accept a microscope since he has to keep the printed matter very close to his face and moreover his hands may not be steady. Younger individuals are more motivated for reading than elder individuals.
In people below 10 years the cause of low vision being mainly congenital and hereditary the improvement was very slight. They had other congenital abnormalities like nystagmus and mental retardation in addition to the eye condition. Out of 21 cases in this age group, 5 were due to congenital causes like microphthalmos and coloboma optic disc and others were due to optic atrophy, myopia and hypermetropia. The cases with myopia and hypermetropia improved with refraction or other low vision aid. High myopia with or without degeneration were found more commonly in the age group between 11 to 30 years, and most of them improved. We found that the telescopic lens was a useful aid in these cases, particularly for the school boys and college students who were able to see distant objects clearly. Contact lenses were tried in some of these cases and were found to be superior to the ordinary spectacles. The results we get in optic atrophy are not encouraging. Among 57 cases of optic atrophy that we have seen, 33% come under the age group below 20 years. This means that either they would not have entered the school or had school education for some time and left it off due to visual handicap. We have been able to help only in 22 cases of optic atrophy.
Type of aids:
1. Telescopic lens
2. Microscopic lens
3. Hand Magnifiers
4. High spherical glasses
5. Ordinary refraction and conventional glasses.
From the analysis, we find that most of the cases would have been helped by careful ordinary refraction. Out of 700 cases, 431 cases improved by refraction-by retinoscopy and subjective examination or by subjective trial with telescope in the trial frame. Microscopic lenses or equivalent high spherical lenses were prescribed for 50 cases. These microscopic lenses are made up of plastic material and each power microscope is equivalent to +4 D. Sph. and this gives the magnification of two times. These glasses should be used only for one eye. The field of vision is less. The printed matter must be kept very close to the face. The spherical and chromatic observations are more when the power increases. So, use of these lenses need much practice and rehabilitation. It is said that these aberratons are minimal in patients with subnormal vision.
Almost every patient with subnormal vision will improve with telescope but these glasses cannot be prescribed because the field of vision will be further restricted. The patient will not be able to move about out-doors because of motion parallax. Nine patients have been advised to use telescopic lenses and they have been specially instructed to use them only in the stationary position.
Selection of suitable cases for fitting low vision aid is as important as fitting the aids. It does not mean that a given case is not worth a trial. The favourable cases which have been benefitted by the low vision aids as we have found in our study are immature cataract, myopia, aphakia, macular degeneration and macular choroiditis. The unfavourable cases are those with retinitis pigmentosa, optic atrophy, retinal detachment and glaucoma. These findings are supported by the reports from New York by Dr. Richard Hoover, and Carl Kupper. Dr. Gerald Fonda has included congenital abnormalities like albinism, coloboma chroid, coloboma optic disc etc. under favourable group. In our analysis, we find that most of these cases are associated with other abnormalities like mental disturbances, nystagmus etc., and so improvement was not appreciable in these cases.
In our series of cases the primary visual need of the patients was to get back vision to normal or near-normal so that they can earn their living by using these aids. Most of them are coming from low income groups and earn their living by working in the fields and some other out-door jobs. Only few were from middle class and their aim was to get vision for reading.
Those people who can go out-doors with their own subnormal vision ian be helped for reading. The patients who needed help for reading, have been tried by ordinary methods of refraction. It is worth prescribing a glass even when there is slight increase in visual acuity by refraction in these cases. It would seem that almost 60% of them improved with ordinary refraction. Various kinds of visual aids are tried in various clinics and the type of aids depends upon the individual need as well as the fashion of the clinic. For example, Maryland workshop prescribed 2.2 telescopic magnifier in 75% of cases. The light house prescribed high addition of spherical glasses in 60% of cases and Dr. Volk employs the aspherical in most of the visual aid prescriptions. High spherical glasses have helped about 50 patients in our series and hand magnifiers in 18 patients.
The high spherical glasses were given only for monocular use and the better eye is used. An addition of +6 D. Sph. for reading could be used for both eyes. If both eyes are used when the power is more than +6 there will be more of convergence and the patient will complain of eye strain. Dr. Gerald Fonda, is of opinion that both eyes could be used even if the power is as strong as + 10 D. Sph. but prisms of appropriate strength with base in should be incorporated in the spectacles. He claims the following advantages:
1. Larger field of vision
2. Greater depth of focus
3. Improved visual acuity
4. Appearance of conventional glass
5. Psychological desirability because patients prefer to use both eyes.
Depend upon various factors as we have already discussed. To summarise, they are (1) patient's age and motivation for reading (2) intelligence (3) patient's need (4) availability of suitable aids and (5) the nature of eye pathology. It is noted as success even when there is very slight increase in visual acuity as assessed by distant vision charts. When the patient is able to recognise the bold letters after many years of blindness it is considered to be a great achievement. For example, a girl aged 9 years who has been well trained in Braille had very poor distant vision. She was tried by a x 10 microscope and she was able to see the letters for the first time. But she needs much practice and training to get accustomed to the printed matter as the Braille has been the source of education so far.
700 cases who attended our low vision aid clinic from November, 1966 were analysed and the data presented. The favourable cases suitable for fitting the low vision aids are discussed. It seems that the best form of aid is proper refraction and prescription of conventional glasses. For reading, if it is the prime need of the patient, most of them are benefitted by simple addition of high plus glasses. Telescopic and microscopic lenses are useful in certain types of diseases.
To Dr. G. Venkataswamy, M.S., D.O., Professor of Ophthalmology, Madurai Medical College, Madurai for allowing me to analyse the data from his records and for the encouragement he gave me in preparing this article.
|1||Tillette C. W. (1958), Amer. J. of Ophth., 48: 186-194.|
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|5||Hoover, R. and Kupper, C. (1959), Amer. J. of Ophth., 48, 177-187.|