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) The World Health Organization welcomes requests for permission to reproduce or translate its publications, in part or in full. Applications and enquiries should be addressed to the Office of Publications, World Health Organization, Geneva, Switzerland, which will be glad to provide the latest information on any changes made to the text, plans for new editions, and reprints and translations already available. © WORLD HEALTH ORGANIZATION 1992 Publications of the World Health Organization enjoy copyright protection in accordance with the provisions ofProtocol2 of the Umversal Copyright Convention. All rights reserved. The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the Secretariat of the World Health Organization concerning the legal status of any country, territory, city or area or of Its authorities, or concerning the delimitation of its frontiers or boundaries. The mention of specific companies or of certain manufacturers' products does not Imply that they are endorsed or recommended by the World Health Organization m preference to others of a similar nature that are not mentioned. Errors and omissions excepted, the names of proprietary products are distinguished by initial capital letters. TYPESET IN INDIA PRINTED IN ENGLAND 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