Blindness in children has many causes. Half of them are avoidable, and suitable cost effective interventions are available. Haroon Awan and Claire Gilbert explain the current global situation

Blindness in childhood is a priority of Vision 2020, a global initiative for the elimination of avoidable blindness (www.v2020.org), even though the worldwide total of 45 million blind people includes only 1.4 million blind children.^{1 2} But blind children have a lifetime of blindness ahead, which affects their opportunities for education, employment, and earning. Blindness that starts early in life adversely affects psychomotor, social, and emotional development. And blind children have a higher death rate than their sighted counterparts.

An estimated 500 000 children become blind each year, but, in developing countries, up to 60% are thought to die within a year of becoming blind.² Almost half of all blindness in children--particularly those in the poorest communities--is due to avoidable causes that are amenable to cost effective interventions.³

Causes in developing countries

Blindness is more common in developing countries firstly because potentially blinding conditions such as vitamin A deficiency, harmful traditional eye remedies, or cerebral malaria are prevalent; these do not occur in affluent societies. Secondly, preventive measures for conditions that have been controlled elsewhere, such as measles, congenital rubella, or ophthalmia neonatorum, are inadequate. And thirdly, facilities and skilled personnel for managing conditions needing surgery are lacking (box).⁴

Causes in middle income countries

In middle income countries, the pattern of causes is mixed, with retinopathy of prematurity emerging as an important cause in Latin America and some eastern European countries.^{5 6} Currently unavoidable causes (the biggest group in affluent countries) include hereditary retinal dystrophies, disorders of the central nervous system, and congenital anomalies. Uncorrected refractive errors cause visual impairment and blindness in all regions, particularly myopia in South East Asia.⁷

Main priorities

Children younger than 5 years need targeting, as this age group has the highest incidence of blindness, and early surgery to restore sight is needed to prevent amblyopia. Priorities include elimination of corneal scarring due to vitamin A deficiency and measles (poorest communities); treatment of cataract (everywhere), screening programmes for retinopathy of prematurity (middle income countries), correction with spectacles for refractive errors (everywhere); and low vision services for children with incurable visual loss (everywhere).

Tackling specific causes of blindness

Vitamin A deficiency

About 140 million children have disorders related to vitamin A deficiency and are at risk of blindness and increased mortality.⁸ Massive international and national efforts for control are in place in countries with death rates among children younger than 5 of more than 50 in each 1000 live births, where vitamin A deficiency disorders are prevalent. Control encompasses promoting breast feeding, home gardening (to increase local production of food rich in vitamin A), control of diarrhoea, fortification of food, education about nutrition, and intermittent supplementation with high dose vitamin A. Since the launch of the global initiative to reduce vitamin A deficiency, in 1998, supplements are combined with immunisation. Between 1998 and 2000 about a million child deaths were prevented.⁹ However, the impact on blindness is more difficult to ascertain, but blind school and community studies show that corneal blindness is less common in young than in older children.¹⁰

Measles

Measles causes corneal blindness through several mechanisms, including acute vitamin A deficiency, exposure keratitis, herpes simplex keratitis, secondary infection, and harmful traditional remedies. As a result of expanded programmes of immunisation, cases of measles have fallen from more than 4 million a year in 1980 to 830 000 in 2001, and global immunisation coverage is currently 72%.¹¹ Declining rates of blindness related to measles in parallel with increasing immunisation coverage has been reported, and, according to anecdotal evidence, corneal ulceration after measles is now uncommon in developing countries.

LOWELL GEORGIA/SPL

Measles: one of the causes of blindness in children

Childhood cataract

Managing childhood cataracts is far more complex than for age related cataracts and needs well trained teams at the tertiary level and long term follow up. Children with cataract need to be identified and referred promptly and barriers overcome through health education--for example, fear that eyes are removed during surgery. In many developing countries, particularly in Africa, paediatric ophthalmology is underdeveloped, but training programmes are becoming established, particularly in India, to meet targets set by Vision 2020 of at least one trained paediatric ophthalmologist for every 50 million of the population by 2010.² Vision 2020 aims to reduce the global prevalence of blindness in children from the current level of 7 in 10 000 children to 4 in 10 000 by 2020. If achieved, the number of blind children would be almost halved, as the child population is projected to stabilise at 2000 million over the next few years.

DAVID MAUGE/AP

Children with cataracts

Retinopathy of prematurity

Excellent neonatal care can prevent retinopathy of prematurity to a large extent, but babies developing threshold disease need to be identified, as treatment of this stage is highly effective at preventing visual loss.¹² Screening programmes are in place in industrialised countries and are being developed in Latin America and large Asian cities.

Refractive errors

Many children with incurable visual loss benefit from low vision services, which facilitate near vision and inclusive education. Often these services are lacking where they are most needed. Refractive errors, particularly myopia, often go undetected, and vision screening in schools with provision of affordable spectacles is another component of Vision 2020.

Multidisciplinary collaboration

Controlling blindness in children is complex, requiring community activities through to sophisticated tertiary eye care services (figure). Multidisciplinary collaboration will be needed with comprehensive service delivery encompassing health promotion; specific preventive measures; optical, medical, and surgical services; as well as low vision care, special education, and rehabilitation. The challenges are to ensure political commitment towards the alleviation of poverty and the development of models that are effective, replicable, sustainable, and equitable and to mobilise the additional resources required.

Magnitude and causes of blindness in children

• The epidemiology of blindness in children reflects socioeconomic development
• The prevalence and magnitude ranges from about 3 in 10 000 children in affluent societies (60 blind children per million total population) to 15 in 10 000 in the poorest communities (600 blind children per million total population)
• Three quarters of the world's blind children live in developing countries
• Some 500 000 children become blind each year, most in developing countries
• Blind children have a high death rate: the prevalence therefore markedly underestimates the burden²

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