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| COMMUNITY EYE CARE |
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| Year : 1997 | Volume
: 45
| Issue : 3 | Page : 189-193 |
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Survey of visual impairment in an Indian tertiary eye hospital
P Herse, VK Gothwal
University of New South Wales, Sydney, Australia
Correspondence Address:
P Herse
University of New South Wales, Sydney
Australia
 Source of Support: None, Conflict of Interest: None  | Check |
PMID: 9475023 
A retrospective survey of 4, 122 consecutive patient records was performed in a tertiary care eye hospital in Hyderabad, India. Data collected included age, gender, visual acuity after completion of treatment and diagnosis. 62.8% of the patients were male. After completion of treatment, 10.8% had low vision (best corrected visual acuity <6/18 to 3/60 in the better eye) and 2.6% were blind (best correct visual acuity <3/60 in the better eye). Most cases of low vision were found in the 50 to 70 year age group (42.9%). The most common visual acuity range after treatment amongst patients with vision loss was <6/18 to 6/60 (71%). The 4 main causes of low vision were cataract (21.4% of low vision group), glaucoma (14.0%), diabetic retinopathy (13.0%), and retinitis pigmentosa (10.7%). The 4 main causes of blindness were glaucoma (16.3% of blind group), diabetic retinopathy (13.2%), corneal opacities (11.6%) and retinitis pigmentosa (11.6%). It is suggested that patients with low vision at the conclusion of treatment be referred to a vision rehabilitation centre. Referral should be made in cases with a best corrected visual acuity <6/18 to 3/60 or with visual field loss to within 15° of fixation. Patients aged under 50 years of age are expected to achieve maximal rehabilitation success. Motivation and vocational requirements should be assessed in older or more complex cases before referral. The data of this study show that about 10% of patients seen at a tertiary care eye hospital in India could benefit from low vision rehabilitation. Keywords: Low vision, blindness, hospital-based assessment, rehabilitation
How to cite this article:
Herse P, Gothwal V K. Survey of visual impairment in an Indian tertiary eye hospital. Indian J Ophthalmol 1997;45:189-93 |
 | RP IS RETINITIS PIGMENTOSA CACG IS CHRONIC ANGLE CLOSURE GLAUCOMA POAG IS PRIMARY OPEN ANGLE GLAUCOMA ARMD IS AGE RELATED MACULAR DEGENERATION COMEAL OPACITY INCLUDES ALL CAUSES OF COMEAL OPACITY
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| RP IS RETINITIS PIGMENTOSA CACG IS CHRONIC ANGLE CLOSURE GLAUCOMA POAG IS PRIMARY OPEN ANGLE GLAUCOMA ARMD IS AGE RELATED MACULAR DEGENERATION COMEAL OPACITY INCLUDES ALL CAUSES OF COMEAL OPACITY
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 | ABK IS APHAKIC BULLOUS KERATOPATHY PBK IS PSEUDOPHAKIC BULLOUS KERATOPATHY COMEAL OPACITY INCLUDES COMEAL DYSTROPHY, COMEAL DEGENERATION, KERATITIS, AND SCARS MACULAR DISEASES INCLUDES HEREDOMACULAR DEGENERATION, MACULAR SCARS, MACULAR HOLES, AND AGE-RELATED MACULAR DEGENERATION THE POPULATION SIZE (616) IS GREATER IN THIS ANALYSIS DUE TO THE EFFECT OF MULTIPLE DIAGNOSES (SEE TEXT)
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| ABK IS APHAKIC BULLOUS KERATOPATHY PBK IS PSEUDOPHAKIC BULLOUS KERATOPATHY COMEAL OPACITY INCLUDES COMEAL DYSTROPHY, COMEAL DEGENERATION, KERATITIS, AND SCARS MACULAR DISEASES INCLUDES HEREDOMACULAR DEGENERATION, MACULAR SCARS, MACULAR HOLES, AND AGE-RELATED MACULAR DEGENERATION THE POPULATION SIZE (616) IS GREATER IN THIS ANALYSIS DUE TO THE EFFECT OF MULTIPLE DIAGNOSES (SEE TEXT)
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About 12 million blind people were estimated to be living in India in 1990, about 15% of the world blind population at that time.[1] The main causes of blindness were listed as cataract, uncorrected refractive errors, corneal opacities, and glaucoma.[2] With the increasing availiability of ophthalmological services, this mountain of mostly treatable blindness is being vigorously attacked. However a significant number of patients either refuse treatment or do not attain normal or near normal vision following treatment. These patients constitute the visually impaired population.
The rehabilitation of people with visual impairment has been relatively ignored in India.[3] Reasons given to explain this apparent lack of interest include (i) the overwhelming demand for cataract surgery, (ii) the lack of postgraduate training in the field of low vision rehabilitation, (iii) the perception that low vision rehabilitation is time consuming and generally unsuccessful, iv) the very poor availiablility of locally made low vision aids, and v) the difficulty and expense in importing overseas low vision aids.[4] Yet visual rehabilition clinics exist, and are successful, in other developing country settings such as Kenya and Uganda.[5] Workers in the field have called for improvement of vision rehabilitation services in India for many years.[3],[4] Yet, to justify the creation of low vision rehabilitation services it is first required to show a need. To assess this need, a retrospective survey of patient files was done in a large regional eye hospital in India.
| Materials and Methods | |  |
| Survey location | | |
Hyderabad is the state capital of Andhra Pradesh. It is a moderately large industrialized city of about 4 million people. The people are predominantly of the Telugu language group, though there is a large Urdu speaking Muslim population. The climate is dry outside of the monsoon period. Hyderabad has 3 tertiary eye care hospitals (1 government and 2 private). This survey was done at the L.V. Prasad Eye Institute which is a private, well-equipped, 60 bed tertiary referral eye hospital offering fellowship training in a range of sub-speciality areas.
| Patient selection and data collection | | |
4, 122 consecutive patient records of fee-paying patients seen for the first time during the 3 month period from 1 June to 31 August 1996 were reviewed for this survey. No patient under the age of 3 years was included in the survey due to the inability to obtain useful visual acuity data. Screening of patient records was done during the last week of December 1996 to allow a minimum of 4 months for completion of treatment and follow-up of cases. Patients were provided with a full range of optometric, medical or surgical treatment, as indicated for their diagnosis. Data obtained from the patient records included i) age, ii) sex, iii) diagnosis (single or multiple), and iv) distance visual acuity in the better eye, either at the end of treatment or at the end of December 1996. All data were coded to maintain patient confidentiality. Recording of a single primary diagnosis was attempted wherever possible. However, multiple diagnosis were required in some instances. For example, an elderly patient with chronic diabetes mellitus may be diagnosed with proliferative diabetic retinopathy, cataract, glaucoma, and retinal detachment. In a case such as this, the main causes of vision loss in the better eye were recorded.
| Definitions of visual impairment | | |
Vision loss is classified using the best corrected distance Snellen visual acuity in the better eye.[5],[6] The classifaction used is shown in [Table - 1].
| Results | | |
| Treatment provided | | |
The most common single treatment provided was surgery (33.5% of patients). The most common surgical procedures performed were cataract extraction (72.1% of surgeries), retinal procedures (17.0%), glaucoma procedures (7.3%), and penetrating keratoplasty (3.6%). Refraction of ammetropias and presbyopia (25.5% of patients) was the other main single treatment provided. It should be noted that refractions were also done on all patients being examined for the first time as a routine procedure and on most post-surgical patients. Non-surgical treatment (41.0% of patients) combines patients who were within normal limits, required medical treatment and/or advice, and patients who refused treatment.
| Vision after treatment | | |
[Table - 1]
After completion of treatment of these 4,122 new patients, 86.6% had no visual impairment, 10.8% had low vision and 2.6% were blind.
| Gender distribution | | |
[Table - 1]
Of these 4,122 patients, 62.8% were male. Of the 448 patients with low vision, 60.3% were male. Of the 104 blind patients, 65.4% were male.
| Age distribution | | |
[Table - 2]
The age distribution of the low vision group was a peaked curve with the greatest number of patients lying in the 50 to 70 year age group (42.8%). The age distribution of the blind group was similarly skewed with the greatest number of patients lying in the 50 to 70 year old age group (43.3%).
| Causes of visual impairment | | |
[Table - 3]
The 4 most common causes of low vision were cataract (21.4%), glaucoma (14.0%), diabetic retinopathy (12.9%), and retinitis pigmentosa (10.7%). The 4 most common causes of blindness were glaucoma (16.3%), diabetes (13.2%), corneal opacities (11.6%), and retinitis pigmentosa (11.6%).
| Characteristics of the low vision population | | |
[Table - 4]
The major causes of vision loss in children were congenital cataract and retinitis pigmentosa. Retinitis pigmentosa was the main cause of vision loss in both the teenage and young adult groups. Cataract, corneal opacities, and diabetic retinopathy were the main causes of vision loss during the fourth decade. In the older adult group the main causes of vision loss were predominantly cataract, followed by corneal opacities, primary open angle glaucoma, and diabetic retinopathy.
| Discussion | | |
| Classification of visual impairment | | |
The WHO classification of visual impairment emphasizes foveal vision while ignoring peripheral visual field loss and patient motivation.[5] This criticism has resulted in a recent modification to the definition of low vision to "a person with low vision is one who has impairment of visual function even after treatment and/ or refractive correction, and has a visual acuity in the better eye of <6/18 to light perception, or a visual field of <10° from the point of fixation, but who uses or is potentially able to use vision for the planning or execution of a task".[7] It should be noted that this new definition has combined parts of the previous classifications of low vision and blindness suggesting that people with very gross visual abilities should not be thought of as "blind". While this enlarged definition of low vision has been accepted by WHO, it has not as yet been used in current clinical studies.[5],[6] To allow comparison with other studies, the commonly used WHO classification of low vision (<6/18 to 3/60) and blindness (<3/60 to no PL) are used in this study.
| Low vision rehabilitation | | |
The data of this survey show that a significant number of patients seen in a tertiary care eye hospital fail to attain normal vision after thorough treatment. Of 4,122 consecutive patients, 448 had low vision, and 104 were blind after treatment. What can be done to improve the vision of these people? Low vision rehabilitation is indicated. Low vision rehabilitation is a multidisciplinary approach combining the skills of optometrists, mobility instructors, and school teachers. In this approach a person with a visual impairment is first seen by an optometrist who determines if magnification would improve the patient's ability to perform a desired task. Magnification is usually provided by optical methods; for example, by spectacles, magnifiers, or telescopes. In general, magnification of near tasks can be provided by using powerful convex lenses. Convention states that the magnification of a convex lens is its dioptric power (F) divided by 4 (for example, a +16.00 D lens is a 4x magnifier). The lens provides magnification by moving the near focus point 4 times closer than the usual reading distance, thus increasing the visual angle of the viewed object 4 times. Stand magnifiers work in a slightly different manner, but the general rule of F/4 remains valid for clinical purposes. For a more detailed discussion of magnification principles the reader is referred to standard texts. [5, 8] Non-optical near magnification of up to 20x can be obtained using a closed circuit television. This excellent low vision aid is widely used in developed countries because of its excellent brightness and contrast control, its zoom magnification features and its wide field of view. Unfortunately, it is expensive (US$ 1,000). A cheaper hand held scanner (HeyeVision) which plugs into a home television is availiable in India from Wavelet (Pune) and may be more suitable if finances are restricted. Laptop computers are excellent aids for the visually impaired. Many computers have enlarged fonts in their word processing programs. Other peripheral devices such as scanners, optical character recognition software and speech synthesizers mean that the visually impaired person can scan any page into their computer and the computer can then speak the print back to them. The rapid development of computer technology for the visually impaired is very exciting. Another commonly used non-optical near magnifier is the photocopy machine. Almost limitless magnification is possible by using the enlarging feature found on most photocopiers. However the cost of photocopies stops this method being used extensively. Magnification at a distance is usually obtained by using telescopes. In low vision rehabilitation, monocular telescopes of 4x to 10x magnification are commonly used because of their light weight. Other factors assessed by the optometrist during the low vision examination include contrast and glare sensitivity, visual field integrity, general mobility, and the degree of motivation towards rehabilitation. If magnification is indicated, the optometrist trains the person in how to use the magnifier.
If a significant visual field loss exists and mobility is impaired, the person is referred to a mobility instructor. Mobility instruction may include use of a sighted guide, white cane or guide dog. Often the patient may require living skills training which includes instruction in how to dress, how to work in a kitchen and how to take the correct medicines from a bottle.This training is either provided by a mobility instructor or a specialist living skills instructor.
If the person is young and still attending school, the optometrist and mobility instructor should consult with the students teachers to help maximize school performance. Topics to be discussed include print sizes to be used at school, contrast enhancement on chalkboards and glare protection. Mainstreaming of visually impaired students in ordinary classrooms is recommended.
| Referral for low vision rehabilitation | | |
In general, any person with a best corrected visual acuity between <6/18 and 3/60 will benefit from magnification at near and should be referred for low vision rehabilitation. From this survey, 10.8% of fee-paying patients examined for the first time fall into this category.
However we should consider the age and motivation of many of these people. A significant number of people will be elderly with multiple handicaps and will have very little desire to go through the difficulties of re-learning how to see with a magnifier. If we wish to maximize the success of a newly established low vision service, we could focus on younger patients who are attempting to enter the workforce, are highly motivated, and are willing to re-learn how to read. For this reason, it is suggested that in a newly opened hospital based low vision service referral should occur for patients aged under 50 years and with a best corrected visual acuity between <6/18 to 3/60.
Using the survey data we find 4.8% of patients seen for the first time with low vision were under 50 years of age. This translates to a low vision referral rate of 2 to 3 patients per day. The most common conditions seen in children would be congenital cataract and retinitis pigmentosa. Retinitis pigmentosa would be the most common condition seen in the teenage and young adult groups.
Mobility is known to be decreased when the peripheral field constricts to within 10° of fixation.[5],[8] To allow simplified mobility training, referral for mobility training should be considered when the peripheral visual field has constricted to within 15° from fixation. The main reasons for presentation for mobility training would be glaucoma and retinitis pigmentosa.
Yet, is it fair to refuse patients over 50 years of age access to the vision rehabilitation services? Obviously, the answer is no. However for this discussion we were considering a newly established hospital based low vision service with little experience and scarce resources. As the service grows, more difficult cases should be tackled. It is interesting to note that some workers in vision rehabilitation feel that referral is indicated when the best corrected vision is 1/60 irrespective of age.[5]
| Setting up a vision rehabilition service | | |
A major concern in vision rehabilitation is that magnifiers are too expensive. If all magnifiers have to be imported from overseas then the costs and importing difficulties would be horrendous. However this does not have to be the case. A simple hand magnifier can be made by threading a string through a hole drilled in the edge of a +16.00 D spectacle lens. Spectacle magnifiers of upto 4x magnification can be easily made in any optical laboratory. A simple stand magnifier can be made by squeezing a +10.00 D spectacle lens into the correct place in a piece of PVC water pipe. Specifications on how to make water pipe stand magnifiers are available in literature.[5] These simple oprical magnifiers can be sold to patients for less than Rs. 100. Low vision telescopes can be purchased in India for Rs. 2,500. Inexpensive low powered sports binoculars can be used if the specialist low vision telescopes are too expensive. A -10.00 D spectacle lens held at arms length makes a very useful field expander for glaucoma or RP patients. Probably the most useful low vision aid is a bright reading lamp which can be purchased for a few hundred Rupees. On the professional level, a fully equipped low vision diagnostic set can be purchased in India for less than Rs. 10,000. Establishing and maintaining a low vision service does not have to be expensive.
An equally common concern is that India has no resources or suppliers for low vision. While service are limited, a useful range of suppliers and information sources are availiable. A range of low vision aids, diagnostic sets and telescopes can be purchased either from Baliwalla & Homi (Mumbai) or Shah & Shah (Calcutta). Information about low vision aids and rehabilitation services can be obtained from the Blind Men's Association (Ahmedabad). Closed circuit televisions and computer aids can be obtained from Wavelet Group (Pune). A further excellent source of vision rehabilitation information is the Internet. By using a computer (Internet), it is possible to find an extensive list of low vision services and information concerning eye disease. Of particular note is the webpage of the Royal Blind Society in the UK.
Visual rehabilitation is often ignored in the treatment of patients with eye disease. This survey has demonstrated that after completion of treatment in a tertiary care eye hospital about 10% of patients remain visually impaired. Most cases have a best corrected visual acuity of better than 6/60 and could benefit from magnification. Many cases of peripheral field loss could benefit from mobility and living skills training. The cost of establishing visual rehabilitation services is not great and the need is there. Ophthalmology in India is obligated to ensure that appropriate magnifying devices and training are provided as part of the complete treatment of eye disease.[9]
| References | | |
| 1. | Bhattacharjee J, Devadethan D, Sharma R, Saini N, Datta K. Methods for estimating prevalence and incidence of senile cataract blindness in a district. Indian J Ophthalmol 1996;44:207-11.  |
| 2. | Malik S. Blindness scenario in south east Asia: overview. In: Kalevar V, editor. Proceedings of the All India Ophthalmological Society Conference. New Delhi: All India Ophthalmological Society; 1993. p 591-92. |
| 3. | Kulasekharan P, Vidyavati M. Blind school children: an integrated survey. In: Kalevar V, editor. Proceedings of the All India Ophthalmological Society Conference. New Delhi: All India Ophthalmological Society; 1988. p 411-14. |
| 4. | Desai NC, Desai R, Iyer KK, Sharma R. Low vision therapy: Indian perspective. In: Kalevar V, editor. Proceedings of the All India Ophthalmological Society Conference. New Delhi: All India Ophthalmological Society; 1991. p 614-15. |
| 5. | Silver J, Gilbert CE, Spoerer P, Foster A. Low vision in east African blind school students: need for optical low vision services. Br J Ophthalmol 1995;79:814-20. [ PUBMED] |
| 6. | Carreras FJ, Rodriguez-Hurtado F, David H. Ophthalmology in Luanda (Angola): a hospital-based report. Br J Ophthalmol 1995;79:926-33. [ PUBMED] |
| 7. | The management of low vision of childhood. In: Proceedings of WHO/PBL Consultation; 1992; Bangkok. Geneva: World Health Organization; 1993. |
| 8. | Farrall H. Optometric Management of Visual Handicap. London: Blackwell Scientific Publications; 1991. p 30-190. |
| 9. | Fonda GE. Optical treatment of residual vision in diabetic retinopathy. Ophthalmology 1994;101:84-88. [ PUBMED] |
[Table - 1], [Table - 2], [Table - 3], [Table - 4]
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