Prevention ol childhood bUndness
World Health- Orpalzatloa Geaen Prevention of childhood blindness Prevention of childhood blindness
World Health Organization Geneva 1992 WHO Library Catalogumg in Publication Data Prevention of childhood blindness. r.Blmdness - in infancy & childhood 2.Biindness - prevention & control ISBN 92 4 156151 3 (NLM Classification: WW 276)
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91 /9088-Macmillan/Clays/GCW-s8oo Contents
Preface vu
Introduction I
I. Prevalence and epidemiology of childhood blindness 2 Definition 2 Prevalence 2 Causes 3 2. Causes of childhood blindness and current control measures 6 Causes of blindness in the prenatal period 6 Causes of blindness in the neonatal period II Causes of blindness in childhood I5
3· Strategies for prevention 25
4· Major areas of action 35 Information, education and communication 35 Behavioural changes 35 Human resource development 35 Strengthening of the infrastructure 36 Appropriate technology 36 Legislation 36 Evaluation 36 Research 37
5· Intersectoral collaboration and the role of nongovernmental organizations 38
6. Priority areas for future action 4I Data compilation 4I Blinding malnutrition 4I
V PREVENTION OF CHILDHOOD BLINDNESS
Measles-related blindness 41 Blinding corneal lesions 42 Traditional eye care 42 Ophthalmia neonatorum 42 Congenital rubella syndrome 42 Congenital cataract and glaucoma 42 Genetically determined blinding conditions 43 Ocular trauma 43 Retinopathy of prematurity 43 Visual rehabilitation 43 NGO collaboration in preventing childhood blindness 43 Epidemiological research 44
References 45
Glossary 46
Annex 1. WHO Meeting on the Prevention of Childhood Blindness 4 7
Annex 2. Screening for severe retinopathy of prematurity 50
vi Preface
Blindness affects some 1.5 million children in the world today, with severe adverse consequences for their development and education. Despite the fact that many of the blinding dis orders affecting infants and children are either preventable or curable, there are still an estimated half million new cases of childhood blindness every year. The bulk of this problem is found in developing countries, where the life expectancy of the affected children is severely reduced. However, childhood blind ness is also a challenge to developed countries, as increasing knowledge and novel techniques open up new possibilities for preventive measures. In collaboration with two nongovernmental organizations working in the field of childhood blindness-the Christoffel Blin denmission (Germany) and Sight Savers (United Kingdom) WHO convened a global meeting on the Prevention of Childhood Blindness, hosted by the International Centre for Eye Health in London, from 29 May to I June I990. The participants in the meeting are listed in Annex I. This book is based on the pre sentations and discussions at the meeting. The valuable support of the two above-mentioned organizations in making possible both the meeting and this publication is gratefully acknowledged. The colour photographs were provided by the International Centre for Eye Health, except for those relating to trachoma, which are included by courtesy of Teaching Aids at Low Cost, St Albans, England.
vii Introduction
Visual inputs account for a major part of the sensory stimuli that are essential for the complete development of a child in its formative years. Deprivation of vision in the early years of life can have far-reaching psychosocial, educational and economic effects, not only for the affected child but also for the family and the community. Children who become blind also have a high prospective mortality rate. Traditionally, blindness prevention programmes have fo cused mostly on blindness in adults. This was largely the result of the preponderance of blindness in later adult life owing to aging-related diseases, e.g., senile cataract, but it was also partly because of the lack of technology for the effective prevention and control of the various types of childhood blindness. Nutritional blindness was generally tackled outside blindness prevention programmes. With increasing knowledge and improvements in therapy derived from clinical and basic research over the past decade, it is now possible to prevent or treat effectively a number of condi tions that are potentially blinding in childhood. Moreover, global initiatives in the area of child survival are meeting with increas ing success, and will continue to do so in the coming years. The focus is therefore now more on morbidity and specifically, the prevention of childhood disability. This is shown by the Inter national Initiative against A voidable Disablement (IMPACT) already being undertaken in this field and the interest displayed by a number of international nongovernmental organizations.
1 1. Prevalence and epidemiology of childhood blindness
Definition A blind child is a person under r6 years of age with correc ted visual acuity in the better eye of less than 3/60 (count fingers at 3 m) or a central visual field of less than roo (1). However, children with severe visual impairment (corrected visual acuity in the better eye of 3/60 or better but less than 6/6o), although not classified as blind under the above definition, have special educational needs which should not be ignored. Some children have monocular blindness due to trauma, amblyopia or other causes, but because they have good vision in the fellow eye they are not classified as blind.
Prevalence The available data underestimate the size of the problem for four main reasons:
• Blindness registration data in developed countries are of ten incomplete, although this is probably less true for children than for adults. • Population-based surveys in Africa and Asia usually fail to take into account children who are in residential schools for the blind. • Certain blinding conditions of childhood are associated with high mortality, e.g., vitamin A deficiency, chromo somal abnormalities, prematurity and multiple disabilities from rubella. Blindness is associated with a higher-than normal child mortality rate in developing countries.
2 PREVALENCE AND EPIDEMIOLOGY OF CHILDHOOD BLINDNESS
• Children with multiple handicaps, including visual dis ability, are often not registered as blind, or at least not until they are very much older.
A conservative estimate of the number of blind children in the world, based upon the limited amount of data available, is given in Table 1.
Table 1. Estimated number of blind children in the world.
Region Population Blindness Estimated 0-15 years prevalence no. of (millions, 1989) (per 1000) blind children
Africa 240 1.1 264000
Latin America 130 0.6 78000
North America, Europe, Japan, Oceania, former USSR 240 0.3 72000
Asia 1200 0.9 1 080000
Total 1810 1 494 000
Causes Childhood blindness can be simply classified from an etio logical viewpoint, as follows:
• factors operating at conception, e.g., genetic diseases; • factors operating in the intrauterine period, e.g., rubella; • factors operating around the time of birth, e.g., retin opathy of prematurity; • factors operating in childhood, e.g., vitamin A deficiency.
The major causes of childhood blindness in any one com munity are determined by the socioeconomic status of the people and the level of health care services.
Communities with severe poverty and poor health care In most of Africa and Asia, and some isolated foci in Latin America and the Caribbean, corneal scarring accounts for
3 PREVENTION OF CHILDHOOD BLINDNESS
50-70% of all childhood blindness. The major causative factor is vitamin A deficiency, often associated with severe protein-energy malnutrition, measles and malabsorption of nutrients due to diar rhoea. Other causes include traditional eye medicines and gono coccal ophthalmia neonatorum. The prevalence rate may exceed 1 .o per 1000 children and mortality in these children is high.
Communities with moderate socioeconomic development and health care In these situations, children usually have access to measles immunization, and malnutrition is uncommon. Corneal scarring is seen less frequently, and congenital cataract and congenital glaucoma, often in association with congenital rubella syndrome, become the major causes of childhood blindness. This is the present position in many parts of Latin America, probably in eastern Europe, and in the more economically developed com munities of Africa and Asia. The prevalence of childhood blind ness is probably around 0.5 per 1000 children.
Communities with well-developed health care services In this situation, blindness from measles or rubella is un common, as a result of immunization programmes. Malnutrition does not occur. Blinding corneal scar is rarely seen in children, and congenital cataract is often familial. The main causes of blindness are genetically determined diseases of the retina and optic nerve, and retinopathy of prematurity which is seen in children with very low birth weight who are given intensive early postnatal care. The prevalence of childhood blindness is approx imately 0.25 per 1000. This is the present position in North America, Australia, western Europe, Japan, New Zealand and some large cities in developing countries.
Small or isolated communities In communities that practise close intermarriage, genetically determined diseases are the most important cause of childhood blindness. These tend to occur in small island communities, in certain countries in the Eastern Mediterranean region, and in communities with particular ethnic or religious traditions.
It is important to note that the prevalence and causes of childhood blindness show wide regional variations, depending largely on the standard of health services. Furthermore, it must
4 PREVALENCE AND EPIDEMIOLOGY OF CHILDHOOD BLINDNESS be acknowledged that there are very few reliable data on the prevalence or incidence of childhood blindness. Estimates should therefore be viewed with caution but, for the various reasons outlined on pages 2-3, they generally tend to underestimate the size of the problem. The definition of childhood blindness used here excludes children with severe visual impairment, who also have special educational requirements. The number of severely visually Im paired children may equal the number of blind children.
5 2. Causes of childhood blindness and current control t·neasures
Blindness in infancy is caused by events occurring in preg nancy and the perinatal period, whereas blindness in the older child is more commonly caused by nutritional deficiencies, infec tions, tumours, injuries, neurodegenerative diseases and toxic/ metabolic diseases.
Causes of blindness in the prenatal period In general, around so% (30-70%) of childhood blindness in industrialized countries is prenatally determined (Table 2). There are two main groups from the point of view of prevention:
• genetic factors: the major cause of childhood blindnesss in Europe; • nongenetic factors: outside developed countries, intra uterine infection with rubella and toxoplasmosis becomes significant. Other causes not genetically determined in clude infection with cytomegalovirus, some forms of con genital cataract and congenital glaucoma, other congenital malformations (anophthalmos, microphthalmos, colo boma) and intrauterine toxicity from smoking, alcohol consumption, and possibly ingestion of environmental toxins. Genetic causes What little information there is on the proportion of child hood blindness that is prenatally and genetically determined comes mainly from developed countries. The genetically deter mined blinding disorders are a heterogeneous group: the most
6 CAUSES OF CHILDHOOD BLINDNESS AND CURRENT CONTROL MEASURES
Table 2. Proportion of blindness that is prenatally or genetically determined in various countries
Region Year Source of data Proportion of Proportion of and blindness of blindness country prenatal origina genetically {%) determined8 {%)
Africa Malawi 1977 Survey of children 31 Nigeria 1979 Schools for the blmd 26 United Republic of Tanzania 1978 Schools for the blind 16 Average 25 The Americas Argentina 1990 Hospital 49 Chile 1974 School for the blind 67 Jamaica 1988 School for the blind 72 Uruguay 1986 School for the blind 51 Average 60 Eastern Mediterranean Cyprus 1972 School for the blind 82 79 Lebanon 1975 School for the blind 69 68 Saudi Arabia 1985 School for the blind 59 57 Average 70 70 Europe Netherlands 1975 Institutes/schools for the 62 45 visually handicapped Norway 1990 Blindness registration 68 29 Turkey 1989 Schools for the blind 60 United Kingdom England 1986 Blindness registration 50 England 1988 Blindness registration 50 Scotland 1987 Schools for the blind 48 Average 65 45 Western Pacific Japan 1985 Schools for the blind 73
8 - Data not available.
7 PREVENTION OF CHILDHOOD BLINDNESS common, at least in the developed countries, are the hereditary retinal dystrophies and optic atrophy. Also important are microph thalmos, congenital cataract, congenital glaucoma, retinoblastoma and albinism. Hereditary retinal dystrophies include Leber congenital am aurosis, classic retinitis pigmentosa of early onset, pigmentary retinopathies associated with other syndromes, and cone, cone-rod, and macular dystrophies. Optic atrophy of genetic origin usually has autosomal domi nant transmission, and frequently becomes apparent in adoles cence. Microphthalmos may be an isolated finding or part of a more complex syndrome. It may also be associated with ordinary or cystic colobomata of the uvea. Microphthalmos and anophthal mos may occur in the same family and genetically should be considered together. Congenital cataracts are much more common in the Medi terranean basin and in some tropical countries than in northern Europe. The causes also differ in different countries. For ex ample, approximately half of the congenital cataracts in Europe and North America are thought to be genetically determined, whereas a high proportion in other countries is probably due to rubella. Bilateral congenital cataracts, dense enough to restrict vision severely, can be treated by surgery within the first few months of life. Intracapsular cataract extraction is not feasible in children, but a satisfactory procedure is extracapsular extraction with simple irrigation and aspiration. Some surgeons find there are fewer complications if the lens is removed, using a special instrument (vitrector). The immediate correction of the ensuing aphakia is important if amblyopia is to be prevented. Congenital glaucoma is thought to have a genetic origin in some societies, although in developed countries there is not usu ally a family history of the disease. However, with recessive conditions, there may be no family history, the disorder being diagnosed only when an affected infant is born. Congenital glau coma can also be treated surgically, although supplementary topi cal medication may be necessary. Early detection of retinoblastoma is part of some blindness prevention programmes. There has been a general impression that retinoblastoma has a higher incidence in some African and Asian countries than in Europe and America, and it has also been suggested that some countries may have a more severe form of the disease. Management is by early detection and treatment, often enucleation of the eye. Radiotherapy may be an option
8 CAUSES OF CHILDHOOD BLINDNESS AND CURRENT CONTROL MEASURES where facilities exist and when the condition is diagnosed early enough. Albinism is one of the less common causes of blindness, but is an important cause of visual disability. The present control measures for single-gene disorders in industrialized countries include the screening and management of newborn carriers of abnormal genes, screening of potential parents for carrier status, genetic counselling and prenatal diag nosis with or without selective abortion. These methods are generally time-consuming, may require advanced technology, and may not be ethically acceptable in some societies. Autosomal recessive disorders account for a high proportion of single-gene disorders in Cyprus and Lebanon, probably be cause of consanguineous marriages. Around 20% of all marriages in Turkey are within the same family, and the corresponding figure in north-western Pakistan is as high as 8o%. Consanguin ity is known to be associated with a greater risk of autosomal recessive diseases. Although there is no reliable evidence that genetic coun selling makes any difference to the actual incidence of genetic eye disease, it is of great importance to individual families.
Nongenetic causes The embryo is susceptible to environmental influences that are relatively innocuous in the mature individual but which can cause severe malformation in the unborn child. These influences include rubella virus, ionizing radiation and alcohol. The congenital rubella syndrome (CRS) occurs throughout the world in infants whose mothers have been infected with rubella virus during the first 20 weeks of pregnancy. In such nonimmune mothers the virus may cross the placenta, resulting in various systemic and ocular abnormalities. These include congenital heart disease, deafness, microcephaly, cataract, microphthalmos, glaucoma and retinopathy. Congenital rubella syndrome is likely to be a significant cause of blindness and other childhood dis abilities in communities with epidemics of rubella infection. Many children with CRS have multiple disabilities, so the mor tality rate in the first five years of life is high. CRS and childhood blindness from its ocular manifestations can be prevented by ensuring that all women of childbearing age are immune to the rubella virus. Active immunity is usually permanent after natural infection, and is probably also lifelong
9 PREVENTION OF CHILDHOOD BLINDNESS after immunization. A number of immunization strategies have been tried to achieve this objective, but none has so far been entirely successful.
• A strategy of immunization of girls between the ages of ro and 15 years, supplemented by selective immunization of women of childbearing age found to be negative for ru bella antibody has been adopted in the past in Australia, the United Kingdom, and some other European countries. The drawback is that natural circulation of the virus is maintained by children, unprotected men and young women. • Another approach has been immunization of all children from the age of 12 months with combined measles mumps-rubella vaccine (MMR), with rubella immuniz ation for all children under 12 years at the beginning of the programme. The rationale is to interrupt transmission of rubella virus in young children, thus reducing the pos sibility of exposure of susceptible women. This strategy has been adopted mainly in Canada and the United States of America. Since the early 1980s, there has been a con siderable decline in the incidence of rubella and CRS in the USA.
To eliminate CRS, a mixed approach is probably preferable, to ensure both interruption of transmission and protection of groups at risk. However, there are two problems with the use of rubella vaccine in developing countries. First, few developing countries have documented whether they have a CRS problem. Second, unless rubella immunization coverage reaches at least 8o0,6, the introduction of rubella immunization for young chil dren could actually increase the incidence of CRS by allowing more women to reach childbearing age without acquiring immunity. Universal rubella immunization is thus appropriate only where immunization coverage is both high and sustainable. Early diagnosis and referral to specialized centres for treat ment of congenital cataract or congenital glaucoma can restore sight or prevent further visual loss in children with CRS. Optic nerve hypoplasia, in isolation or associated with changes in the central nervous system, may represent a signifi cant proportion of blindness at birth in developed countries. It is associated with maternal alcohol use, diabetes, and use of certain drugs in pregnancy. However, these conditions are rarely re ported in developing countries.
10 CAUSES OF CHILDHOOD BLINDNESS AND CURRENT CONTROL MEASURES
The incidence of intrauterine infection as a cause of blindness and damage to the central nervous system in newborn infants is likely to be higher in conditions of poverty, poor hygiene and poor nutrition. Intrauterine infection due to rubella, toxoplasma, or cytomegalovirus may result in a variety of ocular abnormalities or be associated with encephalopathy and blindness from optic atrophy. Transmission from the mother to the fetus of human im munodeficiency virus (HIV) will have implications in childhood owing to an increased susceptibility to viral diseases of the eye, particularly the retina.
Causes of blindness in the neonatal period During the perinatal and neonatal period (birth and the first four weeks of life), there are three major groups of disorders that cause blindness: birth injuries, ophthalmia neonatorum, and retinopathy of prematurity.
Birth injuries By the beginning of the 1970s in developed countries, ob stetric practices had developed to the point where physical trauma during labour and delivery was becoming uncommon. However, in developing countries, obstetric trauma may still be an important cause of visual impairment associated with central nervous system damage. For example, it has been suggested that there is an increased incidence of intracranial haemorrhage asso ciated with obstetric practices in some South Pacific islands. This is an area in which preventive measures could be relevant. Intrapartum asphyxia, characterized by biochemical events leading to tissue ischaemia and/or haemorrhage, is another poten tial cause of severe brain damage. Asphyxia during birth has previously been considered to be a major cause of blindness. Although adverse intrapartum events can lead to cortical and white-matter damage, resulting in cerebral palsy and cortical blindness, recent evidence based on epidemiological studies sug gests that this is no longer a common cause of childhood blindness.
Ophthalmia neonatorum Ophthalmia neonatorum (ON) (2) is defined as a purulent conjunctivitis occurring during the first four weeks of life. The
11 PREVENTION OF CHILDHOOD BLINDNESS two most common causative agents are Neisseria gonorrhoeae and Chlamydia trachomatis, the former being of more concern here because of its propensity to cause blindness. A number of cases of milder conjunctivitis are caused by a variety of other or gamsms. The eyes of the newborn infant are infected during passage through the birth canal of a mother infected with the causative organisms, and symptoms usually appear within the first three days of life. Approximately 30% of infants with untreated gono coccal ophthalmia neonatorum will develop serious ocular com plications which often lead to blindness. Thus, ON is an ocular emergency and must be diagnosed and treated as quickly as possible. The distribution of ON is worldwide, although the incidence varies widely from country to country. In countries that have excellent antenatal care, the incidence of ON is low. In countries where there is limited antenatal coverage, particularly those where ocular prophylaxis of the newborn is not a common prac tice, ON is an important problem and a significant cause of ocular morbidity and blindness in the newborn. There are three major strategies for the control of ON: pre vention of the disease by antenatal treatment of infected parents, prophylaxis at birth, and treatment of the clinical disease in the newborn. The best method of preventing ON is the diagnosis and treatment of infected mothers in an antenatal care programme. Where this is not possible, the universal use of ocular prophy laxis should be encouraged; this consists of cleansing the eyes of the infant immediately after birth and applying a single dose of a topical agent. Both I% tetracycline eye ointment and I% silver nitrate eye drops are highly effective in prophylaxis. Tetracycline ointment has the advantages of low cost and few side-effects. Old and poorly stored silver nitrate solutions may cause chemical conjunctivitis and occasionally damage the cornea. Treatment of active ON in the newborn must be prompt and thorough. In view of the emergence of penicillin-resistant gono coccal infection in various parts of the world, minimal therapy includes the use of systemic antibiotics, either ceftriaxone or kanamycin, and gentle and frequent cleansing of the eyes fol lowed by application of I ~o tetracycline eye ointment. Tradi tional birth attendants, midwives and other personnel concerned must be trained in the prevention and management of this infec tion. Furthermore, the parents of an infant with ON should be referred for testing for sexually transmitted diseases.
12 CAUSES OF CHILDHOOD BLINDNESS AND CURRENT CONTROL MEASURES
Retinopathy of prematurity
Retinopathy of prematurity (ROP) is a potentially blinding condition affecting infants born before term. Retrolental fibro plasia, as it was initially known, was first described in the early 1940s, and about a decade passed before it was discovered that the high concentrations of supplemental oxygen being adminis tered to premature infants at that time were significant in its production. There followed a period of reduced use of oxygen, and while this produced a pronounced decline in the incidence of ROP, the condition did not disappear altogether, as expected. Furthermore, because of the oxygen restriction, there was an unacceptable rise in infant morbidity and mortality. Since then, there have been many advances in neonatal man agement which have significantly improved the survival rates of the most immature infants. Recent studies have indicated that the incidence of severe acute ROP and, more importantly, its visually disabling cicatricial sequelae is increasing (the so-called second epidemic), despite careful monitoring of oxygen use. This epi demic is due to the increased survival rate of the most immature infants, who are the ones at greatest risk; they are now practically the only ones who suffer from blinding ROP. The lower the weight and gestational age at birth, the higher the incidence of ROP. Current quoted incidence rates among survivors are of the following order: acute ROP, so-Ss% (birth weight< 1000 g) and 3S-60~ 0 (birth weight< ISOO g); cicatricial ROP, 4-1s% (birth weight< 1000 g) and I.S-9.0% (birth weight< ISOO g). The international classification of ROP (3, 4) has permitted direct comparison between centres, although vari ations in methods, frequency of examination and duration of follow-up still influence the reported incidence rates. Many aspects of the etiology of ROP remain poorly under stood, and the condition still occurs in infants who have received meticulous neonatal care. No particular concentration or duration of oxygen therapy has been proved to influence either its in cidence or its severity and it is tempting, therefore, to dismiss the role of oxygen in the condition. This would be incorrect, as the reduction of severe ROP in the larger premature neonate is the result of intensive monitoring of oxygen use. Many risk factors have been proposed but, on analysis, few have proved to be independently significant. The possible role of light is currently being investigated. To summarize the current state of knowledge, ROP is not entirely preventable and is considered to be a conse quence of prematurity and other perinatal problems and their
13 PREVENTION OF CHILDHOOD BLINDNESS treatment. Possible ethnic differences have received scant attention. Recent studies on the natural history of this condition have provided interesting insights of both theoretical and practical importance. While the incidence and severity of retinopathy are influenced by neonatal events, it appears that the time of onset and the final outcome are determined more by the stage of devel opment of the infant. Thus the onset is significantly later in the smaller, often sicker infant than in larger infants, and it is not closely related to oxygen therapy. Acute ROP develops over a relatively narrow gestational age range, being rare before 3 I weeks and after about 44 weeks. After this age, stage I or 2 acute ROP (implying only a visible demarcation line or ridge between the anterior avascular retina and the posterior vascularized re tina) does not progress to blindness, and it is thus stages 3 and 4 (fibrovascular growth and retinal detachment) which are of major concern. These two stages develop in eyes in which the retino pathy commenced in zone I or 2; stage 3 is reached between approximately 34 and 42 weeks gestational age (see Fig. I and Annex 2). About 30 years ago, it was speculated that early identifica tion of ROP by an ophthalmologist, through observation of the retinal arterioles, might lead to prevention of serious disease. For a variety of reasons, this proved not to be so, and for many years the role of ophthalmologists was one of identification only, as Right Left
Fig. 1. Retinopathy of prematurity. Right eye: stage 3 ROP in zone 2 extending to involve about 11 clock hours. Left eye: stage 3 ROP in zone 2 involving 4 clock hours.
14 CAUSES OF CHILDHOOD BLINDNESS AND CURRENT CONTROL MEASURES they could neither influence the course of the condition, nor offer effective treatment. This situation changed in 1988 with the pub lication of the results of a multicentre trial of cryotherapy for ROP (5), which reported that the use of cryotherapy for stage 3 + disease resulted in a significant reduction in unfavourable out comes. This finding, confirmed in a subsequent article, brought ROP into the ophthalmologist's therapeutic domain for the first time. Screening for ROP thus assumed practical importance. There are as yet no generally agreed strategies for this, but it is clearly an important issue. Firstly, the aim and target group of the screening must be determined. Secondly, it must be borne in mind that the examination is time-consuming, requires con siderable expertise and cannot be delegated to junior ophthalmic staff. On a worldwide basis, potentially blinding ROP is rela tively uncommon, and as ophthalmic skills are in short supply, screening for ROP should be as simple and take as little time as possible. Proposed guidelines for screening for severe ROP are contained in Annex 2.
Causes of blindness in childhood Xerophthalmia The extent of vitamin A deficiency throughout the world has been estimated on the basis of clinical surveys (6). Worldwide, some 350 ooo new cases of severe eye damage occur annually among preschool children, and an estimated 6o% of these chil dren die within a year of becoming blind. Newer techniques applied in recent surveys to assess vitamin A deficiency (relative dose response and conjunctival impression cytology) suggest that 40-60% of the preschool population in some developing coun tries is subclinically affected. At the public health level, vitamin A deficiency occurs in an environment of deprivation-social, economic and ecological. It tends to occur in geographic clusters within this environment, and to be seasonal, peaking during periods of food shortage and after epidemics of measles and diarrhoea! and other infectious diseases. Breast-feeding has been found to be protective. The blinding form of vitamin A deficiency most often occurs in chil dren between one and three years of age, soon after they have been weaned onto diets that are virtually devoid of vitamin A and frequently low in fat. Vitamin A deficiency also affects chil dren in the later preschool years, but it does not often cause
15 PREVENTION OF CHILDHOOD BLINDNESS blindness at that age unless it is accompanied by protein-energy malnutrition. Nevertheless, children in this age group who are deficient in vitamin A also have a high mortality rate. School-age children are also affected by milder ocular symptoms of night blindness and Bitot's spots, but there are few data to indicate how their health and survival are influenced by vitamin A deficiency. The effect of vitamin A deficiency on the incidence, duration and severity of enteric and systemic infections remains unclear at present, although there is some evidence to suggest that it is associated with increased morbidity from diarrhoea and respira tory infections in childhood. Studies from Africa have reported that measles-related blindness and death may be associated with vitamin A deficiency. The mechanisms by which vitamin A influences ocular le sions are better understood than its role in influencing mortality and other morbidity. Its role in the formation of rhodopsin, which is necessary for low-light vision, is well recognized, and its function in maintaining the differentiation and thus the integrity of epithelial cells is also documented. It is likely that this latter role accounts for its influence on morbidity and mortality, but there is some evidence that there may also be a direct effect on the immune system. There is no single noninvasive method for making an ade quate assessment of marginal or subclinica1 vitamin A deficiency as a public health problem. Available methods include serum vitamin A distribution curves, the relative dose response, con junctival impression cytology, and rapid dietary assessment based on the frequency of consumption of foods containing vitamin A. A combination of two or more of these methods provides the most reliable estimate of the magnitude of the subclinical prob lem. Strategies for prevention should begin with an analysis of the local situation. Of the several possible interventions, em phasis has been given in the past 20 years to the periodic (4-6 month) distribution of a concentrated vitamin A supple ment-usually 200 ooo IU (IIo mg of retinol palmitate) (8). Mass distribution of vitamin A will certainly prevent blindness, but it will only be successful in areas where the existing in frastructure can ensure consistent delivery, through universal or targeted programmes, to the most vulnerable groups-a task that has proved impossible in several countries. A disease-targeted intervention strategy of distribution to children with measles, protein-energy malnutrition, acute respiratory infection, diar-
16 CAUSES OF CHILDHOOD BLINDNESS AND CURRENT CONTROL MEASURES
rhoea or corneal ulcers would be expected to prevent or minimize corneal damage and its blinding sequelae. The identification of high-risk groups, such as refugees, recent migrant populations, particularly in periurban slums, vic tims of natural disasters and populations with high mortality among children under five, could make it easier to set priorities for intervention. Special emphasis should be placed on reaching children under two years of age. Fortification of a common food with vitamin A, although potentially attractive where an adequate delivery infrastructure exists, has not been found to be an effective or sustainable option except in a few situations, such as refugee camps. The most promising long-term preventive strategy is the horticultural ap proach, which focuses on increased accessibility of naturally occurring and inexpensive foods containing vitamin A, combined with education to increase their use as weaning foods and in the diet of preschool children. These approaches are coming back into favour and should be the focus of attention during the 1990s. Activities to improve the vitamin A status of groups known to be deficient may be integrated into other public health pro grammes, such as: immunization programmes, which reach infants and pre school children periodically; diarrhoea} disease control programmes, where an ade quate diet after the attack is known to be vital for sub sequent health; clinics for children under five, including growth moni toring, where monthly contact with mothers provides an opportunity to emphasize the importance of vitamin A in the diet and provide supplements both to children and to their mothers. Income-generating activities, family planning programmes and literacy programmes aimed at women also provide an opportun ity for education about the need for vitamin A. Social marketing techniques, using strategies that define acceptable concepts, be haviour, and products, and promote or distribute them, offer a measure of success not achieved by traditional educational pro grammes. Surveillance involving not only ophthalmologists, but also paediatricians, general practitioners and primary health care workers in areas where blinding malnutrition is prevalent could be effective. "Sentinel clinics" could serve as a tool for trend assessment and evaluation of intervention programmes.
17 PREVENTION OF CHILDHOOD BLINDNESS
There is an urgent need to raise the consciousness of govern ment health ministries and health workers, national and inter national funding agencies, nongovernmental organizations and others involved in public health about the importance of vitamin A in the prevention of childhood blindness and the promotion of child survival and health. Awareness campaigns are urgently needed, as are efforts to improve vitamin A intake through sus tainable and locally appropriate intervention programmes.
Measles Surveys conducted in schools for the blind in East Africa and the Sahel area of West Africa have shown that approximately 70~ 0 of blindness in children is due to corneal scarring. In half these children, the corneal scarring followed infection with measles. Although it has been known for many years that measles is associated with corneal scarring in Africa, the precise nature of the relationship has been controversial. Measles is a severe disease in most developing countries, with a fatality rate of more than r%. This high rate is probably related to a num ber of factors including the severity of infection, the nutritional status of the child, the age at infection and the lack of health services. Blindness following measles is the result of corneal ulcer ation. Differences in the clinical appearance, response to treat ment and visual outcome of such corneal ulceration have suggested different etiological mechanisms, which are described below.
Measles keratitis. Children with measles have conjunctivitis, and many of them develop a punctate keratitis, which may be come confluent. Measles keratitis is usually self-limiting, and confined to the corneal epithelium. If the eye is closed or pro tected with antibiotic eye ointment, the keratitis heals without any residual corneal damage. Harmful eye medicines. Because of the known risk of blind ness, the parents of children with measles, living in rural areas where health services are inaccessible, may attempt to treat con junctivitis due to measles with traditional eye remedies. Occa sionally, such medicines may damage the cornea by direct physical trauma, by the action of toxic chemicals, or by the introduction of bacterial or fungal pathogens. This damage is often bilateral and severely affects the cornea, resulting in signi ficant visual loss or blindness.
18 CAUSES OF CHILDHOOD BLINDNESS AND CURRENT CONTROL MEASURES
Recurrent herpesvirus infection. Herpesvirus infection may be triggered by a febrile illness such as malaria or measles, or by any illness that reduces cell-mediated immunity. In Africa, most children with herpesviral keratitis have severe and deep corneal ulceration, which is likely to cause significant scarring. Studies have shown that so% of all herpetic ulcers in children in Africa occur under the age of two, 37% are bilateral, and 63% show a widespread, "geographical" configuration. The diagnosis of her pesviral keratitis is frequently missed or delayed because of the atypical presentation. In addition, antiviral drugs are often un available outside major eye centres. Consequently, herpesviral keratitis is a major cause of corneal scarring in African children. Vitamin A deficiency. In Africa, measles is the commonest precipitating factor for vitamin A deficiency. Measles is associ ated with anorexia, vomiting and diarrhoea, all of which reduce the amount of vitamin A available to the child. At the same time, measles is associated with a greater demand for vitamin A. The combination of decreased supply and increased demand may tip the balance in a child who already has marginal liver stores of vitamin A. The result is an acute and rapidly progressive, often bilateral, corneal ulceration with resultant blindness and a high mortality rate. It is believed that the blinding propensity of measles is gen erally low outside Africa, although ocular involvement in the form of conjunctivitis and superficial punctate keratopathy is common. Treatment with vitamin A has been shown to prevent the progression of corneal ulceration due to vitamin A deficiency in measles, and a recent small study has also suggested that vitamin A reduces mortality from acute measles in Africa (9 ). The etiology of measles-associated corneal ulceration is fur ther complicated by the fact that many of the above-mentioned conditions can occur simultaneously and may be interrelated. Confluent keratitis and herpesviral keratitis are usually unilateral and non-perforating in character, while corneal ulceration due to vitamin A deficiency and traditional eye medicines is often bi lateral, deep and perforating. Childhood blindness from measles is therefore more likely to be due to vitamin A deficiency or harmful practices. The first and most important step in the prevention of measles-associated blindness is immunization against measles, which has been shown to give effective and long-term protection. The use of harmful eye medicines can be prevented by dialogue and the education of traditional healers.
19 PREVENTION OF CHILDHOOD BLINDNESS
Herpesviral keratitis in children is often associated with measles, malaria or malnutrition. The prevention of these three disorders would reduce the incidence of herpesviral keratitis in children. Appropriate training for eye workers should ensure that herpesviral disease is diagnosed promptly, and the wider avail ability of an appropriate antiviral eye ointment should lead to more effective treatment and less corneal scarring. All children with acute measles infection in developing countries should be given 200 ooo IU of vitamin A orally (Ioo ooo IU for children under I year or less than 8 kg in weight) as soon as possible after the diagnosis is made. A careful examination of the eyes of children with measles should be performed daily, preferably by a trained eye worker, for evidence of corneal involvement. Any child with any sign of xerophthalmia should be given a full course of vitamin A treatment (i.e. 200 ooo IU on two con secutive days, and a further 200 ooo IU four weeks later; children under I year should receive half the doses) (8). Any child with a corneal ulcer associated with measles should be treated with (a) topical antibiotic ointment; (b) a full course of vitamin A; (c) topical antiviral ointment, if there is clinical evidence of herpesviral keratitis or if the corneal ulcer fails to respond to treatment with antibiotics and vitamin A; and (d) an eye pad, if there is danger of corneal perforation.
Trachoma Trachoma is one of the most common infections in the world and, while not in itself a major cause of blindness in children, it is a major cause of ocular morbidity in children in impoverished communities, particularly in Asia and Africa (10). It is necessary to control trachoma infection in childhood in communities where it is endemic in order to reduce corneal scarring both in childhood and in adult life. Education in per sonal hygiene (particularly face-washing) and fly control through community sanitation are important public health measures for the control of inflammatory trachoma. Topical chemotherapy (tetracycline I%) may be used to treat individuals or commu nities with active inflammatory disease. Although trichiasis is generally a late complication of tra choma, it is not uncommon in children in some hyperendemic areas, and it may lead to blindness. Surgical correction would be indicated in such circumstances.
20 CAUSES OF CHILDHOOD BLINDNESS AND CURRENT CONTROL MEASURES
Ocular trauma Despite the importance of ocular trauma and the potential for its prevention, it is only recently that its prevalence, causes and severity have been described using an epidemiological approach. Ocular trauma, in children as well as in adults, represents a major cause of monocular blindness. The development of perma nent amblyopia is a real concern in childhood, often occurring in spite of good anatomical and cosmetic repair. Trauma to the eye, although significant, is not a major cause of bilateral blindness in children, and therefore does not show up in blindness prevalence data. Sympathetic ophthalmia affecting the fellow eye is a rare occurrence. The following points have emerged from recent epidemio logical studies:a
• Males have higher rates of ocular trauma than females. • Children between 5 and 14 years old represent 6o-8o% of all cases of trauma in childhood. • Among girls, accidents occur equally at all ages, whereas among boys the risk of injury increases markedly from the age of 7 years. • 75% of accidents happen when no adult is present (lack of supervision). • A great deal of the damage is done in active sports, espe cially among boys over 8 years ( overexuberance, care lessness during play, bouts of temper).
Many direct injuries to the eye result from everyday activi ties (at home, at school, during leisure hours) which present numerous hazards. Children are particularly vulnerable to the dangers of badly designed toys or while playing with sharp ob jects, fighting with sticks or fists, throwing stones, etc. Penetrating injuries tend to occur in younger children, whereas contusion injuries occur in the older age group. Accord ing to hospital statistics, perforating injuries represent 8-20% of ocular trauma in children. The prognosis for this type of lesion is worse than in adults and, despite recent surgical advances, has not improved in recent years, particularly in the developing countries.
a Unpublished WHO document PBL/MTG/CB/90.II; available on request from Programme for the Prevention of Blindness, World Health Organization, I2II Geneva 27, Switzerland.
21 PREVENTION OF CHILDHOOD BLINDNESS
Ocular trauma remains one of the commonest indications for enucleation among children. In addition, post-traumatic amblyo pia is of great concern. The time that elapses before medical care is sought greatly influences the outcome. Accurate diagnosis and prompt treatment are essential. In view of the many underlying causes of ocular injuries in children, urgent action is needed in the following areas:
• creation of a safer environment; • education of the public (better parental supervlSlon of children's activities); • legislation (restricting dangerous toys, fireworks, airguns, etc.; enforcing the wearing of seat-belts in motor vehicles); • immediate treatment of eye injuries (early diagnosis, easy access to primary eye care, referral systems for tertiary care).
Harmful eye practices Harmful eye practices may be defined as the application of substances, mechanical devices and heat to the ocular surfaces and adnexa by traditional healers or lay persons, resulting in visual disability, blindness or disfigurement. Although harmful eye practices are widespread throughout the world, there are insufficient data to determine how much childhood blindness they cause. Studies in East Africa have sug gested that 20-25% of childhood blindness may be attributable to the use of harmful eye medicines. They appear to be of greater significance in developing countries, where certain forms of tra ditional medicine are practised, than in industrialized countries. Some home remedies may also be harmful and hazardous to the eye. The significance of harmful eye practices as a cause of blind ness is often not evident because they are often applied to treat existing ocular disease. Thus the harmful practices frequently lead to blindness when used to treat otherwise benign diseases (e.g., minor ocular trauma and conjunctivitis), but the blindness may be attributed to the disease itself. Traditional treatment may also exacerbate serious ocular damage and blindness due to com mon conditions (e.g., measles, corneal trauma, corneal infections). The substances and practices described below are highly destructive of ocular tissue.
22 CAUSES OF CHILDHOOD BLINDNESS AND CURRENT CONTROL MEASURES
Topical substances include naturally occurring fluids, solids, pastes, compounds, powders, human body fluids, domestic ani mal fluids and excreta, commercial chemicals and fuels. Many of these substances, especially those that are caustic or of high pH, and those containing particulate foreign matter, are potentially blinding. Examples include extracts of tree roots, leaves, bark, herbs and vegetable foodstuffs, powdered charcoal, human urine and saliva, animal blood, cattle dung, kerosene and petrol. The application of hot objects to the ocular adnexa may pro duce lid retraction and exposure keratopathy. Application to the ocular surface often results in blindness. Examples include metal probes heated by fire and applied externally to the upper lid to reverse trichiasis, thermal cautery for dacryocystitis, hot poul tices applied to the globe for ocular disease. The manipulation of the ocular adnexa or intraocular struc tures with mechanical devices, particularly couching, is not likely to be a significant cause of childhood blindness. Spiritual or ritualistic treatment of ocular disease may delay the patient's recourse to appropriate therapy. It may also be accompanied by potentially harmful practices, as described above. The results achieved by spiritual ocular practices are un known. Examples include N'ganga (traditional healer) treatment in East Africa, grigriseur (Voodoo) medicine in West Africa and the Caribbean, and Dhami Jhankri in Nepal. Harmful eye practices causing childhood blindness are prob ably widespread in developing countries, but are poorly under stood. These practices probably contribute to a greater propor tion of childhood blindness than is currently thought. Medical anthropological research is required in this area. Because these practices are deeply rooted in traditional social and health care systems, behaviour modification through education is necessary to reduce their use. With proper orientation and appropriate training, some of these traditional practitioners could be useful in delivering pri mary eye care. Some success has been achieved in this regard in both Africa and Asia.
Systemic infections Systemic infections in childhood may lead to blindness through involvement of the central nervous system. Among these, cerebral malaria and acute bacterial and tuberculous men ingitis are significant in countries where these infections are com mon.
23 PREVENTION OF CHILDHOOD BLINDNESS
Strategies for the prevention and control of childhood blind ness due to systemic infections are essentially related to the con trol of the primary diseases.
Intracranial space-occupying lesions Early diagnosis of intracranial space-occupying lesions is generally difficult in areas with poor health coverage, and this is further compounded by the lack of adequate neurosurgical facil ities. Delayed diagnosis of intracranial space-occupying lesions in children may lead to irreversible damage to the optic nerve.
24 This seven-year-old child has bilateral mature cataract, present from birth (congenital cataract). Its adequate management usually requires a general anaesthetic and special treatment facilities.
An African infant with a normal right eye but congenital glaucoma in the left eye, as demonstrated by an enlarged and hazy cornea. This infant has a white pupillary reflex in the left eye (leukocoria) due in this case to a malignant tumour of the eye- retinoblastoma.
A newborn baby with an acute conjunctivitis- ophthalmia neonatorum -which if left untreated can lead to corneal ulceration and perforation of the eyes. Various inherited diseases are associated with visual loss in children, including oculocutaneous albinism as in this African child. Bitot's spots seen on the temporal conjunctiva provide the clinical evidence of vitamin A deficiency in this child.
Keratomalacia with sloughing of the This four-year-old child is blind from right cornea is seen in this young child, corneal scarring (right eye leukoma, suffering from severe vitamin A left eye staphyloma) resulting from deficiency and undernutrition. keratomalacia due to vitamin A deficiency. Measles infection may lead to corneal ulceration. This child is very ill with measles and also has eye involvement. Harmful eye practices can result in corneal damage and blindness in children. This eight-year-old African child has three areas of deep corneal ulceration (descematoceles) due to the use of harmful traditional medicines.
Young children can develop florid viral keratitis. This two-year-old African child has a typical branching dendritic ulcer due to human herpesvirus. Trachoma and other eye infections can be spread by eye-seeking flies attracted by ocular and nasal discharges. Frequent face-washing is a simple and effective method for reducing trachoma transmission and infection in children.
Ocular trauma is a common cause of monocular blindness in children. This photograph shows a thorn within the cornea causing intraocular inflammation with a hypopyon. lntraocular surgery on children for congenital cataract usually requires general anaesthesia, good magnification and lighting. Aphakic correction for children in many countries of Asia and Africa is obtained with spectacles.
An African child, suffering from low vision, being trained in f he use of a simple magnifier for reading. 3. Strategies for prevention
A variety of strategies have been developed against the major causes of childhood blindness and the resulting visual loss. It is significant that many of the strategies are directed towards public health measures, rather than eye care itself, because of the many complex factors determining the occurrence and severity of most blinding disorders. Strategies to prevent childhood blindness should address the possibility of intervention at all three prevention levels:
• Primary prevention-prevention of the occurrence of a disease in a population. • Secondary prevention-prevention of sight-threatening complications and visual loss once the disease has ap peared. • Tertiary prevention-minimization of the visual disability resulting from previous disease or injury.
The main strategies for preventing blinding diseases in chil dren are described below. Prophylaxis is the systematic use of a procedure or medi cation for primary prevention of a disorder. One of the most well-known examples in relation to childhood blindness is the use of the Crede method (application of r% silver nitrate solu tion) to protect newborn infants against conjunctivitis due to N. gonorrhoeae. Immunization is another primary preventive strategy, which can be used against infectious diseases with blinding sequelae, i.e., measles and rubella. Appropriate antenatal care is a useful strategy for the pri mary prevention of conjunctivitis in the newborn, since pregnant women can be screened for N. gonorrhoeae. It is also of general value in detecting risk factors such as pre-eclampsia and multiple pregnancy, which may lead to low birth weight, prematurity and
25 PREVENTION OF CHILDHOOD BLINDNESS perinatal asphyxia. Fetal monitoring and appropriate timing and method of delivery may reduce this last complication. Neonatal care is the provision of proper care for the newborn baby, such as maintenance of normal body temperature, adminis tration of vitamin K, clearing of the airway and application of the Crede prophylaxis. Improvement of nutrition is a valuable strategy for the pre vention of a variety of disorders. In relation to blinding diseases in children, it refers to a regular intake of vitamin A, which may be achieved through better use of local sources and possibly through the fortification of certain food items or dietary supple mentation with vitamin A capsules. Education as a preventive strategy may include public educa tion through the mass media, to increase general awareness about blinding diseases and their prevention in children, or more speci fic health education about locally endemic diseases or aimed at particular risk groups or target audiences. Examples include pub lic education about measles to improve immunization coverage, or specific education for mothers about weaning foods or the possible dangers of traditional practices. Another recent example is the introduction of social marketing methods to promote better nutrition. Genetic counselling is a primary preventive strategy against genetic disorders. It is being increasingly considered in many countries, but has so far not been implemented on a large scale in view of the resources needed and the complex social and cultural issues involved. Legislation is a primary strategy for the prevention of some causes of childhood blindness. The best-known example is legis lation on the application of the Crede prophylaxis in many coun tries, but other examples include restrictions on the sale of fireworks, standards for the safety of spectacle lenses, domestic products and toys, and laws governing the use of seat-belts in cars. Early recognition and treatment of potentially blinding dis ease are important for secondary prevention of childhood blind ness. This may be important in a number of conditions, such as conjunctivitis in the newborn, xerophthalmia, congenital cata ract, congenital glaucoma and ocular injuries. This strategy may also include the tertiary prevention of blindness in children through surgery for conditions such as congenital cataract. In the case of children, early surgical treatment 1s generally indicated because of the risk of amblyopia. (continued on p. 34)
26 Table 3. Prevention of prenatal causes of childhood blindness
Primary Secondary Tertiary Human Facilities/ resources/training supplies 1\) C/1 -....j -1 :D > Congenital cataract and congenital glaucoma of genetic origin -1 m Genetic counselling Early diagnosis Low-vision care for Recognition by health Tertiary Cl iii those w1th poor visual worker surgical/anaesthetic C/1 Avoidance of consan- Early surgical outcome facilities "T1 0 guineous marriage for treatment Specialist care :D autosomal recessive (ophthalmic genetics) ., :D disorders Visual rehabilitation desirable m
Retinoblastoma Genetic counselling Early detection Rehabilitation in cases Specialist care Access to specialized of bilateral enucleation (ophthalmic genetics, centres including Targeting of Early treatment oncology) desirable radiotherapy high-risk groups (radiotherapy or surgery)
Other prenatally determined conditions Education regarding Early detection of ab- Low-vision care for Training in paediatric Tertiary facilities use of drugs, smoking, normalities especially optimal use of residual ophthalmology for diagnosis and alcohol in pregnancy in high-risk babies. vision management Proper management of visual impairment Table 4. Prevention of neonatal causes of childhood blindness 1\) ., ()) :a Primary Secondary Tertiary Human Facilities/ m
Birth asphyxia Improved obstetric Early identification of Low-vision services Training in obstetric As needed for care visual disturbance in care for personnel adequate obstetric anoxic infants concerned care
'Unpublished WHO document WHO/VDT/89.447, 1989. 2 See reference 3. "V w :D 0 m Herpesviral keratitis Control risk factors, Early diagnosis and Optical iridectomy, Training of primary Antiviral drugs, e.g., vitamin A defici- referral for antiviral keratoplasty in a few health care workers e.g., idoxuridine ency, measles, therapy cases in primary eye care malaria Low-vision services w "D 1\) :Dm Surgical correction of trichiasis/entropion (uncommon in child hood) Ocular trauma Accidental injury (..) !11 (..) -4 Legislative measures, Early recognition and Specialized surgical Training of primary Preferably tertiary :J:J e.g., regarding seat primary treatment intervention, health care workers in surgical facilities ,. m-4 belts, fireworks, etc. e.g., repair of primary eye care C) ffi Speedy referral for retinal detachment, !11 Public education definitive treatment keratoplasty Ophthalmic surgery "T1 0 :J:J Adequate care and "11 :J:J repair of injuries m Non-accidental injury (battered child syndrome) Identify high-risk Ophthalmic exami- Surveillance for late Social workers for Facilities for complete groups nation as part of complications counselling eye examination, multidisciplinary including general an Counselling assessment Low-vision care aesthesia 1 See reference 8. PREVENTION OF CHILDHOOD BLINDNESS Improved hygiene and care, particularly during illnesses may reduce both the incidence and the severity of some blinding disorders. Examples include good hydration and topical treat ment of secondary eye infections for children with measles, cleanliness during epidemics of conjunctivitis, and oral rehydra tion of children with diarrhoea. Finally, improving the socioeconomic development of a com munity can be seen as a preventive strategy for a variety of conditions and diseases. The above list does not reflect any order of priority, which will obviously vary according to the local situation. Tables 3-5 set out in summary form the management of the various causes of blindness in children from the perspective of primary, secondary and tertiary prevention, together with an outline of the needed human resources, training and infrastructure. The referenced texts should be consulted for more detailed information. 34 4. Major areas of action The prevention of childhood blindness and the control of its causes require action on a number of fronts. The following list, although not exhaustive, covers the major areas that can be tackled by blindness prevention programmes and that warrant priority action. Information, education and communication Information, education and communication (IEC) in pri mary health care and eye care are relevant to nearly all the direct and indirect causes of childhood blindness. They also play a pivotal role in blindness prevention and general health promo tion, by bringing about changes in lifestyles and cultural behav iour patterns that are detrimental to eye health in children. As well as creating an awareness of the magnitude and preventability of childhood blindness, particularly in developing countries, they can play an important role in encouraging action by governments and nongovernmental agencies to prevent unnecessary blindness. Behavioural changes The adoption of desirable breast-feeding practices and the appropriate weaning of infants are important for the prevention of childhood blindness. Poor nutrition in pregnant and lactating women and in infants, sometimes based on traditional cultural beliefs, may well need to be modified through IEC. Cultural patterns that favour consanguineous marriages are more difficult to change. Compliance with health care measures where avail able, e.g., immunization and antenatal care, often requires a change in the attitudes and behaviour of family members. Human resource development This is a critical issue in all aspects of maternal and child care. Antenatal, perinatal and postnatal care, and primary eye 35 PREVENTION OF CHILDHOOD BLINDNESS care as an integral part of primary health care, are key areas where enhanced and extended training of health personnel is needed. In relation to management of eye conditions in neonates, e.g., cataract, glaucoma, and retinopathy of prematurity, special ized training of ophthalmologists in selected centres is necessary. Strengthening of the infrastructure In order to guarantee effective medical, surgical and re habilitative services to control childhood blindness, the necessary equipment, supplies and appliances must be provided. Selected tertiary-level or intermediate-level facilities may need to be set up or strengthened with this in mind. Such action should be combined with the training for ophthalmologists referred to above. Appropriate technology A large number of children, both the visually impaired and the totally blind, could be assisted in their educational and other activities through the provision of optical aids. Low-cost spec tacles (I I) and unsophisticated yet effective low-vision aids, such as magnifiers, could be produced to meet this need, parti cularly in developing countries. Legislation Regulatory and legislative measures, such as laws on the use of seat-belts in motor vehicles, the control of fireworks, and safety standards for spectacle lenses, have proved useful in redu cing childhood blindness from trauma in several countries. Evaluation Evaluation is an integral part of the management of activities for the prevention and control of childhood blindness. Special emphasis should be placed on evaluating the efficiency and the effectiveness, particularly the cost-effectiveness, of interventions. 36 MAJOR AREAS OF ACTION Research The need for both epidemiological and operational research cannot be overemphasized. An analysis of the magnitude of the problem of childhood blindness and its causes in different situ ations would provide the basis for both realistic planning and subsequent evaluation. Medical anthropological and behavioural research could form the basis for intensified and appropriately targeted IEC and for social marketing efforts. 37 5. lntersectoral collaboration and the role of nongovernmental organizations International and national nongovernmental organizations can play a leading role in securing greater political support and more resources for the prevention of childhood blindness. Being flexible in their approach, they are often in a position to initiate action and provide initial inputs into activities to prevent blind ness in children. They can also facilitate the involvement of the local community in control activities. As well as ministries of health, several other sectors and agencies, directly or indirectly concerned with eye health, play a critical role in controlling factors that pose a threat to children's sight. These include, among others, ministries of agriculture, education, the environment, and information and broadcasting. Active collaboration between these sectors would provide the necessary multidisciplinary base for interventions against causes of blindness in children. Today's greater awareness of blindness on a global scale owes much to the work of WHO and nongovernmental organ izations. While WHO has provided the major thrust in this field, encouraging governments of both developed and developing countries to adopt appropriate policies, the nongovernmental organizations have complemented these efforts at a national level and have extended blindness prevention services to less well served areas. A great number of organizations throughout the world are concerned with blindness control activities. These include organ izations with an international focus on funding or technical assistance for blindness prevention activities, publication of educational materials, or extensive public outreach and political advocacy. 38 INTERSECTORAL COLLABORATION Among the areas of action of nongovernmental orgamz ations, the following can be highlighted: • Human resources training and health education continue to be major areas of interest and commitment. While staff training initially took place on an informal basis, in several countries such training has become institutionalized and NGOs have assisted national programmes in meeting their staffing requirements. Several of these training programmes, as well as being innovative in approach and content, have afforded the opportunity for collaboration between nongovernmental organizations themselves and between the organizations and WHO. The production of training materials is an other example of such collaboration. In the area of health education, the expertise and ex perience of nongovernmental organizations have been of immense value in the production of health education materials both for the public and for policy-makers. Nongovernmental organizations have also been involved in or supported research and evaluation in the area of eye health education. • Adaptation of technological developments to make them appropriate for developing countries in terms of cost and maintenance has been another important contribution by nongovernmental organizations. Examples of this are local production of eye medication and low-cost spectacles and ophthalmic instrumentation. Initial experience has been shared with a number of countries, often through ex pertise provided by nongovernmental organizations. • In connection with the delivery of eye care, nongovern mental organizations have actively supported outreach ac tivities such as mobile units, "eye camps" and peripheral hospitals to provide essential eye care to underserved populations. A number of international nongovernmental organizations have shown a renewed interest in addressing the problem of avoidable blindness in children, in addition to their existing commitment to and support for special education and rehabilitation of blind children. Such an interest. could facilitate the inclusion of activities for the prevention of childhood blindness in national blindness prevention programmes as an integral part of primary health care. 39 PREVENTION OF CHILDHOOD BLINDNESS • The advocacy role played by international nongovern mental organizations, both individually and collectively through their membership of the International Agency for the Prevention of Blindness (IAPB), has led to useful interaction with ministries of health in a number of coun tries, in both initiating and developing national pro grammes. Through participation in national committees or councils, nongovernmental organizations have been able to help governments to develop appropriate strategies and have provided resources to support eye care activities within national programmes. • Resource mobilization by nongovernmental organizations has been a key factor in providing financial support to national programmes directly or through WHO in fur thering blindness prevention activities. 40 6. Priority areas for future action Data compilation More data are required on the prevalence, incidence and causes of childhood blindness in different parts of the world. These can be obtained by: • further analysis of existing data from population-based surveys; • maintenance and analysis of registers of blind people in countries where such registers exist; • examination of blind children in special schools for the cause of their blindness, taking into account possible selection bias; • review of hospital data, where available, regarding causes of childhood blindness. Blinding malnutrition Since vitamin A deficiency is still the major global cause of childhood blindness, renewed efforts should be directed at this problem. Nutrition education combined with increased avail ability of inexpensive local sources of vitamin A should be a major priority in this decade. However, it is also important in the short term to ensure that vitamin A supplements are readily available to communities at high risk of vitamin A deficiency and blindness. Measles-related blindness Measles, particularly in Africa, may result in acute, rapidly progressive and often bilateral corneal ulceration with resultant 41 PREVENTION OF CHILDHOOD BLINDNESS blindness. Intensified efforts are needed to promote a higher rate and extended coverage of measles immunization. Children with measles should be given supplementary vitamin A. Blinding corneal lesions Primary health care workers and other concerned health per sonnel need to be trained in the recognition and management of the early signs of sight-threatening corneal lesions. Traditional eye care Because some traditional home remedies and eye care practi ces used on children in certain societies are harmful and may lead to blindness, efforts must be made to increase community aware ness of their danger. Furthermore, a dialogue should be held with traditional healers, imparting to them the knowledge and skills they need to provide more appropriate eye care. Ophthalmia neonatorum Blinding conjunctivitis in the newborn poses an increasing problem in some parts of the world, particularly where routine prophylaxis at birth has been discontinued. It is, therefore, im perative that routine prophylaxis be reintroduced or strengthened in the countries concerned. It should consist of two steps: clean sing of the eyelid, followed by a single application of tetracycline I% eye ointment or silver nitrate I~,~ eye drops. The use of polyvidone iodine eye drops in the prophylaxis and treatment of ophthalmia neonatorum requires investigation. Congenital rubella syndrome Congenital rubella syndrome is a preventable cause of child hood blindness. In areas of the world where this is a recognized problem, appropriate immunization programmes should be im plemented to reduce its incidence. Congenital cataract and glaucoma In order for patients with congenital cataract and congenital glaucoma to achieve useful vision, early recognition, referral and treatment are essential. 42 PRIORITY AREAS FOR FUTURE ACTION Genetically determined blinding conditions Genetically determined diseases are increasingly being re cognized as major causes of blindness. With specialist knowledge and new techniques, some are potentially preventable. There is a need for further multidisciplinary consultation in this area. Ocular trauma The action required to prevent ocular trauma involves in creased public education, legislation and appropriate man agement at the primary health care level, including early recognition, first-line treatment and prompt referral. Retinopathy of prematurity Ophthalmic screening of small premature babies should be carried out whenever possible to identify cases of stage 3 thresh old ROP, where blindness may be prevented by cryotherapy. Visual rehabilitation Many children with severe visual disability can benefit greatly from optical correction. Services for refraction, provision of spectacles, and low-vision care must, therefore, be provided on a large scale in countries where they are currently unavailable. Additionally, action must be taken to make eye care personnel aware of the need for educational and rehabilitative services for incurably blind children. NGO collaboration in preventing childhood blindness Many of the nongovernmental organizations working in blindness prevention are already playing a significant role in controlling childhood blindness, and this could be strengthened by further increasing public awareness of ways of preventing childhood blindness in all sections of society. 43 PREVENTION OF CHILDHOOD BLINDNESS Epidemiological research Epidemiological studies are required to identify and evaluate the major risk factors involved in certain types of childhood blindness and to assess the impact and cost-effectiveness of vari ous possible alternative interventions. These could be carried out in collaboration with nongovernmental organizations. 44 References r. International statistical classification of diseases and related health problems. Tenth revision. Geneva, World Health Organization, 1992. 2. Conjunctivitis of the newborn: prevention and treatment at the primary health care level. Geneva, World Health Organiza tion, 1986. 3. Committee for the Classification of Retinopathy of Pre maturity. An international classification of retinopathy of prematurity. British journal of ophthalmology, 1984, 68: 690-697· 4· Brown DR, Biglan AW, Stretavsky M. Screening criteria for the detection of retinopathy of prematurity in patients in a neonatal intensive care unit. Journal of pediatric ophthalmol ogy and strabismus, 1987, 24: 212-214. 5. Cryotherapy for Retinopathy of Prematurity Cooperative Group. Multicenter trial of cryotherapy for retinopathy of prematurity: preliminary results. Archives of ophthalmology, 1988, 106: 471-479· 6. Sommer A. Field guide to the detection and control of xeroph thalmia, 2nd ed. Geneva, World Health Organization, 1982. 7· Mamdani M, Ross D. Vitamin A supplementation and child survival; magic bullet or false hope? London, London School of Tropical Medicine and Hygiene, 1988 (EPC Publication No. 19). 8. Vitamin A supplements. A guide to their use in the treatment and prevention of vitamin A deficiency and xerophthalmia. Geneva, World Health Organization, 1988. 9. Hussey GD, Klein M. A randomized controlled trial of vi tamin A in children with severe measles. New England journal of medicine, 1990, 323: 160-164. 10. Dawson CR, Jones BR, Tarizzo ML. Guide to trachoma con trol. Geneva, World Health Organization, 1981. 11. The provision of spectacles at low cosi. Geneva, World Health Organization, 1987. 45 Glossary amblyopia Dimness of VISIOn without detectable or ganic lesion of the eye anophthalmos Congenital absence of one or both eyes aphakia Absence of the lens of the eye coloboma A mutilation or defect, especially a congen ital fissure of any part of the eye descemetocele Hernia of Descemet's membrane (a thin membrane between the connective tissue and the endothelial layer of the cornea) hypoplasia Defective or incomplete development hypopyon An accumulation of pus in the anterior chamber of the eye leukocoria A white pupil as seen in reflected light leukoma Milky white opacity of the cornea low vision A level of vision implying severe visual dis ability, but not blindness for legal or social purposes microphthalmos Abnormal smallness of the eyes monocular Pertaining to or having only one eye ophthalmia Severe inflammation of the eye or of the conjunctiva residual vision Remaining functional vision in an eye affec ted by an impairing disorder or injury retinopathy Any noninflammatory disease of the retina staphyloma Protrusion of the cornea or sclera, resulting from inflammation trichiasis A condition of ingrowing hairs about an ori fice, or of ingrowing eyelashes vitrectomy Removal of the vitreous body of the eye xerophthalmia Conjunctivitis with atrophy and no liquid discharge, producing an abnormally dry and lustreless condition of the eyeball; it is due to a deficiency of vitamin A 46 Annex 1 WHO Meeting on the Prevention of Childhood Blindness List of participants Professor F. Billson, Head, Department of Clinical Ophthalmol ogy, Sydney Eye Hospital, Woolloomooloo, New South Wales, Australia (Chairman) Dr A. Cherinet, Programme Manager, National Programme for the Prevention of Blindness, Addis Ababa, Ethiopia Dr H. Faal, Consultant Ophthalmologist, Coordinator, Gambia National Eye Plan, Royal Victoria Hospital, Banjul, The Gambia Dr A. Foster, Senior Lecturer, International Centre for Eye Health, Institute of Ophthalmology, London, England Professor B. Jay, Department of Clinical Ophthalmology, In stitute of Ophthalmology, London, England Professor G. J ohnson, Director, International Centre for Eye Health, Institute of Ophthalmology, London, England (Vice-Chairman) Professor M.D. Khan, Department of Ophthalmology, Post graduate Medical Institute, Lady Reading Hospital, Pesha war, North-West Frontier Province, Pakistan Professor M. Marsetio, Chairman, Department of Ophthalmol ogy, School of Medicine, University of Indonesia, Jakarta, Indonesia Dr E. Maul, Associate Professor, Department of Ophthalmology, Catholic University of Chile, Santiago, Chile Dr D. McLaren, Senior Lecturer, International Centre for Eye Health, Institute of Ophthalmology, London, England Dr D. Minassian, Senior Lecturer, International Centre for Eye Health, Institute of Ophthalmology, London, England Professor T.N. Nguyen, Director, National Institute of Ophthal mology, Hanoi, VietNam 47 PREVENTION OF CHILDHOOD BLINDNESS Dr R. Pararajasegaram, Regional Chairman, International Agency for the Prevention of Blindness, New Delhi, India (Rapporteur) Dr R. Riise, Chief Medical Officer of Hedmark County, Hamar, Norway Professor F. Sayegh, Head, Department of Ophthalmology, Jor dan University Hospital, Amman, Jordan Dr F. Sayek, Coordinator for Blindness Prevention, Ministry of Health and Social Assistance, Ankara, Turkey Dr B. Underwood, Assistant Director for International Program Activities, National Eye Institute, National Institutes of Health, Bethesda, MD, United States of America Representatives of other organizations Christoffel Blindenmission Mr C. Garms, Executive Director, Christoffel Blindenmission, Bensheim-Schoenberg, Germany Dr A. Hennig, Medical Adviser/Consultant, South Asia Region, Kathmandu, Nepal Dr D. Yorston, CBM Continental Office for Africa, Nairobi, Kenya Helen Keller International Inc. Ms A. Ralte, Acting Director, Vitamin A Technical Assistance Program, New York, NY, USA International Agency for the Prevention of Blindness ( IAPB) Dr C. Kupfer, President, IAPB, National Eye Institute, National Institutes of Health, Bethesda, MD, USA International Eye Foundation Ms V.M. Sheffield, Executive Director, International Eye Foun dation, Bethesda, MD, USA Dr L. Schwab, Ophthalmologist, International Eye Foundation, Bethesda, MD, USA Royal Commonwealth Society for the Blind ( RCSB) Mr A. Johns, Executive Director, RCSB, Haywards Heath, West Sussex, England Mr K. Carey, Director, Overseas Services, RCSB, Haywards Heath, West Sussex, England Dr R. Whitfield, RCSB/OEU Eye Care Consultant for Africa, Nyeri, Kenya 48 WHO MEETING ON THE PREVENTION OF CHILDHOOD BLINDNESS Dr G. Kothari, Child Eye Care Consultant, Sight Savers, Bom bay, India United Nations Children's Fund Mr P. Greaves, Senior Advisor, Nutrition Programme Division, New York, NY, USA World Blind Union Professor A.R. Fielder, Vice-Chairman, Royal National Institute for the Blind Prevention of Blindness Research Sub-Com mittee, Birmingham and Midland Eye Hospital, Birming ham, England Secretariat Dr G. Clugston, Nutrition, WHO, Geneva, Switzerland Dr N. Cohen, Expanded Programme on Immunization, WHO, Geneva, Switzerland Dr I. Darnton-Hill, Regional Adviser on Nutrition, WHO Re gional Office for the Western Pacific, Manila, Philippines Dr A. Modjtabai, Regional Adviser on Noncommunicable Dis eases, WHO Regional Office for the Eastern Mediterranean, Alexandria, Egypt Dr A.-D. Negrel, Ophthalmologist, Programme for the Preven tion of Blindness, WHO, Geneva, Switzerland Dr B. Thylefors, Programme Manager, Programme for the Prevention of Blindness, WHO, Geneva, Switzerland (Secretary) 49 Annex 2 Screening for severe retinopathy of prematurity The following guidelines for screening for severe ROP are proposed. I. What is severe ROP? Severe ROP is stage 3 or 4 acute ROP, which does not usually regress. The threshold for treatment is stage 3 disease, invol ving 5 or more contiguous or 8 or more cumulative clock hours. 2. Which babies? Severe ROP is almost completely confined to the following groups: (a) birth weight < I500 g (b) :(:: 3 I weeks gestational age at birth (c) no sickness criteria, e.g., apparently healthy, but falling into one of the above groups 3. When to examine? Infants of 25 weeks or less gestational age at birth should be examined: (a) 7 weeks postnatally, (b) every 2 weeks thereafter until 36 weeks post-menstrual age, and after this only if indicated by clinical appearance. Infants of 26 weeks or more gestational age at birth should be examined: (a) 7 weeks postnatally (b) at 36 weeks post-menstrual age, or within a week or so of this age if to be discharged from hospital around this 50 SCREENING FOR SEVERE RETINOPATHY OF PREMATURITY time. For many in this group, one examination will suf fice. The timing of screening is critical, particularly since the time window for treatment is only about 2-4 weeks. The normal examination undertaken very early may have no screening value and once the infant has been discharged it may be too late for treatment. 4· Examination technique (a) Pupillary dilatation (b) Indirect ophthalmoscopy. 51 SELECTED WHO PUBLICATIONS OF RELATED INTEREST Price* (Sw. fr.) Guidelines for programmes for the prevention of blindness. 1979 (47 pages) 10.- Strategies for the prevention of blindness in national programmes. A primary health care approach. 1984 (88 pages) 11.- Methods of assessment of avoidable blindness. WHO Offset Publication, No. 54, 1980 (42 pages) 4.- The provision of spectacles at low cost. 1987 (30 pages) a.- Field guide to the detection and control of xerophthalmia. 2nd ed. Sommer, A. 1982 (58 pages) 10.- Vitamin A supplements: a guide to their use in the treatment and prevention of vitamin A deficiency and xerophthalmia. 1988 (24 pages) 8.- Guide to trachoma control. Dawson, C. R. et al. 1981 (56 pages) 9.- Conjunctivitis of the newborn: prevention and treatment at the primary health care level. 1986 (31 pages) 13.- Accidents in childhood and adolescence. The role of research. 1991 (224 pages) 35.- Further information on these and other WHO publications can be obtained from Distribution and Sales, World Health Organization, 1211 Geneva 27, Switzerland. *Prices in developing countries are 70% of those l1sted here. • There are an estimated I.s million blind chit· dren in the world. • Every year, approJdmately half a miUion chit· dren become bUnd (about one every minute). e 01 the children going bUnd, about 60% die within one year. In about 70% of new cases, bUndness is due to vitamin A deficiency. Other important causes of loss of vision are conjunctivitis of the newborn, measles, accidents, certain hereditary and con· genital conditions and, in some settings, harmful . traditional practices. Most of these conditions can be prevented or effectively treated by the appfication of rela· tively simple eye care and pubfic health measures, such as immunization, antenatal care, health education, and provision of adequate nutrition. This pubfication reviews the strategies available for prevention of childhood blindness, identifies priorities for action, and calls on governments and nongovernmental and international organi· zations to work together in tackUng the problem. Price: Sw. &.xs.- ISBN 9Z 4 1S6U1 ~ Price in developing countries: Sw. &.xo.so