|COMMUNITY EYE CARE
|Year : 1996 | Volume
| Issue : 1 | Page : 57-60
Childhood blindness in India and Sri Lanka
Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, United Kingdom
Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL
|How to cite this article:|
Foster A. Childhood blindness in India and Sri Lanka. Indian J Ophthalmol 1996;44:57-60
This review article discusses the definition, magnitude, causes and control of childhood blindness and severe visual loss, based upon recent studies conducted in India and Sri Lanka.
In 1990 the World Health Organisation convened a global workshop on childhood blindness which was held in London. One of the recommendations of this workshop was the need for further epidemiological data on the prevalence and causes of blindness and severe visual loss in children in different parts of the world. In 1993 Gilbert and colleagues developed and published a form for recording the causes of visual loss in children which has been accepted by the World Health Organisation Prevention of Blindness Programme as the Standard Reporting Form for documenting the causes of childhood visual loss.
During 1994, two studies were conducted to examine children attending blind schools in India and Sri Lanka, and a 1 week workshop on childhood blindness in South Asia was held at Aravind Eye Hospital for approximately 20 participants from different countries of the region.
This review article will discuss some of the findings of the recent studies and the recommendations of the Aravind Workshop.
| Definition|| |
Childhood is defined as 0-15 years inclusive. The World Health Organisation categories of visual impairment define blindness as a corrected visual acuity in the better eye of less than 3/60, and severe visual impairment as corrected visual acuity in the better eye of less than 6/60 but equal to, or better than 3/60.
| Magnitude|| |
There are as yet no good survey data on the prevalence of childhood blindness from countries in Asia. Registration data of blindness and severe visual impairment of children in European countries suggests a prevalence of approximately 0.3 per thousand children. Data from studies in Nepal and Bangladesh have indicated that the prevalence of childhood blindness ranges between 0.6 and 1.1 per thousand children. A conservative estimate would therefore be 0.5 per thousand children or approximately 200 blind children per million total population. Based on these estimates, there are 200,000 (± 50,000) blind children in India and 4,000 (± 1,000) blind children in Sri Lanka. The incidence of childhood blindness is unknown, but is probably in the range of 20-100 new blind children per year per million total population depending on socio-economic conditions and available health care services.
| Causes|| |
The Standard Reporting Form classifies the causes of childhood blindness, both anatomically and chronologically according to the time of insult (prenatal, peri-natal and post-natal). Rahi examined 1,318 children with severe visual impairment or blindness in 22 schools for the blind in 9 states of India. The major causes of childhood blindness were corneal scar (26%), anomalies of the globe (25%), diseases of the retina (21%) and cataract (12%). Hereditary factors accounted for 23% of the causes of childhood blindness and postnatal factors for 28 %.
The major cause of corneal scarring was vitamin A deficiency, accounting for 19% of all cases (245/1,318). Other causes of corneal scar included measles, harmful traditional medicines and ophthalmia neonatorum. There were marked regional variations in the relative importance of vitamin A deficiency as a cause of childhood blindness. In Kerela 7% of all childhood blindness was attributed to vitamin A deficiency compared to 22% in Uttar Pradesh and 27% in Madhya Pradesh. In Tamil Nadu vitamin A deficiency accounted for 8% (9/120) of childhood blindness in the Madras blind school, compared with 30% (51/168) in the rural blind school at Pralayamkottai.
The causes of congenital anomalies of the globe included microphthalmos 12% (156/1318) and anophthalmos 5%. Microphthalmos and anophthalmos are both present at birth and must therefore be either due to hereditary factors or teratogenic factors operating during the development of the foetus. Retinal disorders accounted 21% of all childhood blindness, the majority being due to retinal dystrophies 18% (242/1318). Retinopathy of prematurity was only found in 3 children. Disorders of the lens were seen in 12% (162/ 1318) of children. Of these 40% had unoperated cataract, 40% were aphakic but amblyopic, and 20% had severe post-operative complications after unsuccessful surgery.
Eckstein, using the same Standard Reporting Form, examined 226 children with blindness and severe visual impairment attending 6 schools for the blind in Sri Lanka. Corneal scar was only seen in 2% of children. Thirty-six percent of children had anomalies of the globe, 22% diseases of the retina, and 17% cataract. Hereditary factors were responsible for 35% of all childhood blindness and post-natal factors for 5%.
These two studies have indicated some similarities and some differences in the pattern of childhood blindness which can be summarised as follows:
- 1. Anomalies of the globe (microphthalmos and anophthalmos) are responsible for approximately one quarter of all cases of childhood blindness and severe visual loss. The causes of these anomalies are, as yet, not determined.
- 2. Childhood cataract accounts for approximately 15% of all causes of childhood blindness. Up to half of these children have not received surgery and the remaining half are blind from a combination of amblyopia or severe post-operative complications.
- 3. Hereditary retinal dystrophies account for approximately 20% of all cases of childhood blindness.
- 4. Corneal scarring, due to vitamin A deficiency, varies from 2% in Sri Lanka to 8% in Kerela and 27% of all causes of childhood blindness in Madhya Pradesh. These marked regional variations are almost certainly due to a combination of socio-economic factors and available health care services.
Having reviewed these 2 recent studies by Rahi and Eckstein, it should be pointed out that although blind school studies are useful in identifying the major causes of childhood blindness, because a large number of children can be examined using a standard protocol by one ophthalmologist in a relatively short time, these studies do suffer from selection bias. Blind school studies, by definition, do not usually include infants and pre-school children. Many schools are situated in urban situations and therefore there is a selection bias against the rural population and particularly poor families. Children with multiple disabilities are often refused entry to blind schools and therefore causes of visual loss with other disabilities tend to be under-represented. Given these limitations, these 2 recent studies of more than 1,500 blind school children do give useful information and insights into the patterns of childhood blindness in India and Sri Lanka which allow consideration to be given to the important avoidable causes for which control strategies should be developed.
| Control|| |
A. Vitamin A Deficiency
A discussion on the assessment and control of vitamin A deficiency is beyond the scope of this review article. With the realisation that vitamin A deficiency is not only a cause of morbidity from blindness but also of morbidity and mortality from diarrhoea and respiratory tract infections, greater emphasis is now being given to the prevention of vitamin A deficiency in children. The studies reviewed in this article have demonstrated that there are marked regional variations in the relative importance of vitamin A deficiency as a cause of childhood blindness. It is likely, although not proven, that the relative importance of vitamin A deficiency as a cause of childhood blindness is a reflection of the regional differences in the prevalence of vitamin A deficiency in children. To confirm this hypothesis would require population based studies of clinical and subclinical vitamin A deficiency in respective pre-school populations.
The most important long-term and sustainable strategy for the control of vitamin A deficiency is an improvement in the nutrition of infants and pre-school children. To achieve this will require, not only health education of urban and rural populations, but a change in the cultural and behaviour practices of mothers and their families. While these long-term control strategies are being implemented it is also essential to make sure that any child with clinical vitamin A deficiency (night blindness, Bitot's spots, corneal xerosis or corneal ulcer) or children at high-risk of vitamin A deficiency (children with measles, obvious malnutrition or malabsorption) receive full and adequate treatment for vitamin A deficiency, ie. vitamin A capsules 200,000 IU on days 1, 2 and 14 (half this dose should be given to children under the age of 1 year).
Immunisation to prevent measles, and the prevention and adequate treatment of gastroenteritis, are also important strategies to remove major risk factors which can lead to vitamin A deficiency.
B. Cataract in Childhood
Studies at Madurai have reported that approximately one quarter of all cataracts in the first year of life are due to rubella infection. This was confirmed using specific IgM antibody titers in blood and saliva. All the rubella cataracts were found to be nuclear in morphology. Further studies are required to document the importance of rubella in causing childhood disability, not only from blindness, but also deafness. If the findings of the study in Madurai are confirmed in other parts of the region then consideration should be given to implementing a rubella immunisation programme. It is likely that a programme to immunise 12 year old females would probably be the safest, but a thorough analysis of the costs and benefits would be required before initiating any programme.
Other causes of cataract in childhood include hereditary factors (approximately one quarter of all cases) with the remaining 50% of cases being of undetermined aetiology. Trauma is an important cause of unilateral cataract in older children, but this does not usually lead to bilateral blindness. The two studies reported indicate that in order to improve the results of visual outcome in childhood cataract, it is necessary to diagnose and treat children with cataract at an earlier stage. This requires a greater awareness on the part of general doctors, paediatricians and general ophthalmologists of the need for early diagnosis, immediate referral and surgical treatment by an experienced paediatric ophthalmologist. To achieve good visual outcome the visual axis must be kept clear and the refractive error fully corrected. The role of intraocular lenses in young children is still an area of contention which will require a well-designed clinical trial before a definitive statement can be made.
C. Congenital Anomalies of the Globe
Microphthalmos and anophthalmos are important causes of childhood blindness in India and Sri Lanka. It is likely that hereditary factors are responsible for some cases, but it is also possible that various teratogenic factors (toxins or maternal deficiencies) could be harmful to the developing foetus. Further work is required to identify the causes of the relatively high proportion of childhood blindness due to these anomalies in India and Sri Lanka.
D. Retinal Diseases
The most important cause of retinal blindness at the present time in both India and Sri Lanka is hereditary retinal dystrophies. Many of these dystrophies are autosomal recessive and therefore difficult to prevent through genetic counselling. Retinopathy of prematurity is still a rare cause of childhood blindness in South Asia. Recent work in Latin America has indicated that retinopathy of prematurity begins to emerge as an important cause of childhood blindness in situations where there are neonatal units and when children with a birth weight of less than 1500gms survive. It is therefore likely that in the next decade, with the development of neonatal care services in the cities of Asian countries, retinopathy of prematurity will begin to appear. It is important for ophthalmologists to be aware of this problem and for paediatric-orientated ophthalmologists to work with neonatologists in order to screen low birth weight children (less than 1500gms) for stage 3 plus ROP in order to provide prophylactic treatment.
E. Low Vision Services
It is increasingly recognised that children with a visual acuity of less than 6/60 but equal or better than 1/60 can usually be assisted with a combination of spectacles and low vision aids (magnifiers) to read normal print. The ability to read normal print allows easier integration into normal schooling for these severely visually disabled children. Children with a visual acuity of less than 6/60 should be fully assessed by a team including a paediatric orientated ophthalmologist, an optometrist with low vision experience and a low vision therapist. Such a team is important in diagnosing, assessing and prescribing the appropriate optical devices for children with severe visual loss. The therapist is essential in training and motivating the child in the use of the low vision aid in order to achieve maximum benefit.
| Conclusion|| |
This brief review article on childhood blindness in India and Sri Lanka has only attempted to identify and discuss strategies for the prevention and treatment of the major causes of bilateral blindness in children. No attempt has been made to discuss the causes and control of unilateral blindness or of lesser degrees of visual loss in children, including refractive errors and amblyopia.
In summary, it can be concluded that:
- 1. There are approximately 200 blind children per million total population in India and Sri Lanka.
- 2. The major preventable cause of childhood blindness is vitamin A deficiency, although there are marked regional variations in the prevalence of this problem.
- 3. Congenital cataract is the most important treatable cause of childhood blindness for which early diagnosis and referral, surgery by an experienced ophthalmologist, and long-term follow-up and management of aphakia and amblyopia are essential.
- 4. The provision of low vision services (by a low vision team) are necessary to enable severely visually impaired and blind children to read and write print through a combination of spectacles and magnifiers.
- 5. Research work is required in order to identify the causes of microphthalmos, anophthalmos and other anomalies of the globe in children in South Asia.
- 6. Surveillance will be increasingly required in neonatal units for the emergence of retinopathy of prematurity as a preventable cause of childhood blindness.
Approximately 50% of all childhood blindness in India and Sri Lanka is potentially avoidable. In order to reduce the incidence of childhood blindness it is necessary to improve maternal and child health services, particularly immunisation, better nutrition and the control of diarrhoea. There is also a need to develop specialised paediatric ophthalmic services for the management of surgically correctable conditions, particularly cataract, and to provide low vision services for severely visually impaired children.
| References|| |
World Health Organisation. Prevention of Childhood Blindness 1992.
Gilbert C, Negrel AD, Foster A, et al. Childhood blindness: a new form for recording causes of visual loss in children WHO Bull 71:485-489, 1993.
Rahi J, Sripathi S, Gilbert C, et al. Childhood blindness in India: causes in 1318 blind school students in 9 states. Eye (in press)
Eckstein M, Foster A, Gilbert CE. Causes of childhood blindness in Sri Lanka: results from children attending six schools for the blind Br J Ophthalmol 79:633-636, 1995.
Aravind Eye Hospital, Childhood Blindness in South-East Asia, Workshop Report 1994.
Foster A, Gilbert CE. Epidemiology of Childhood Blindness. Eye 6:173-176, 1992.
Rahi JS, Sripathi S, Gilbert CE. Childhood Blindness due to vitamin A deficiency in India: regional variations. Arch Dis Chi 72:330-333, 1995.
Eckstein M, Brown D, Foster A. Congenital rubella syndrome in south India: Diagnosing using saliva in infants with cataract, (submitted)