CHILDHOOD BLINDNESS

Statistics confirming the importance of amblyopia as a cause of childhood and lifetime blindness should be an impetus for increasing efforts to address this issue, said Wagih Aclimandos FRCS, FRCOphth, FEBO, speaking at the 2nd World Congress of Paediatric Ophthalmology and Strabismus, “Amblyopia can be easily treated with very good results, but it remains a huge problem worldwide in terms of its prevalence and major socioeconomic impact. In fact, the figures worldwide on blindness due to bilateral amblyopia are almost an embarrassment to the human race,†said Dr Aclimandos, president, European Board of Ophthalmology, and consultant ophthalmic surgeon, King’s College Hospital, London, UK. “The excellent work being done by some and the shortterm initiatives are not enough. We need more funding and a structured, well-conceived plan to tackle this problem.†Dr Aclimandos pointed out that there are 1.4 million blind children in the world, of which 75 per cent live in developing countries. The vast majority of the cases of childhood blindness (~1 million) are found in Asia and most of the rest (~300,000) involve children in Africa. Even though children represent a small minority of the world’s blind population (~3 per cent), the burden of childhood blindness is much more significant when regarded in terms of “blind person yearsâ€. Considering that almost half of individuals who become blind as children survive and face a lifetime of blindness, childhood blindness is second to cataract as a cause of blind person years.

Putting the problem into perspective

Recent studies investigating blindness prevalence and aetiology in different developing countries document amblyopia as a leading cause. Looking at the literature, Dr Aclimandos cited studies from four countries published between 2004 and 2011. Researchers investigating the prevalence and causes of low vision and blindness in Tehran Province, Iran, found that amblyopia due to uncorrected refractive error accounted for 23 per cent of the cases of visual impairment, and it was second only to cataract. A study investigating causes of childhood blindness and visual impairment in Botswana showed refractive error was the most common cause of bilateral visual impairment. In China, a survey of children from birth to six years found that amblyopia was the leading cause of all visual impairment, accounting for about onethird of the affected children. In a study of children living in camps for displaced persons in Khartoum State, Sudan, amblyopia accounted for 33 per cent of cases of blindness and was the second leading cause after corneal opacity.

However, the importance of amblyopia as a leading cause of childhood blindness is a fact that is not sufficiently appreciated. Indeed, some textbook chapters on causes of visual impairment in the paediatric population do not even mention amblyopia, Dr Aclimandos said. He also pointed out that while amblyopia in more developed countries is generally thought of as a unilateral problem, and the concept of bilateral amblyopia has been questioned over the years, if amblyopia is defined by poor vision due to lack of stimulation of the visual cortex, then bilateral amblyopia does exist. “Bilateral amblyopia is very unusual among children living in more developed countries, but it is much more prevalent in third world countries where children are affected by bilateral deprivation, such as from undiagnosed bilateral cataracts, or have uncorrected bilateral high refractive error that is naturally occurring or the result of aphakia after cataract surgery,†Dr Aclimandos explained.

He noted, however, that unilateral amblyopia also has an important impact. These individuals suffer from worry about the loss of vision in the normal eye, and while there are some controversial data on this issue, according to the Rotterdam Study, amblyopia nearly doubles the lifetime risk of losing the use of the fellow eye. In addition, a population-based study in the UK identifying individuals with unilateral amblyopia reported a 23 per cent rate of loss of vision in the non-amblyopic eye over a two-year period. Fear of losing the good eye leads the individuals with unilateral amblyopia to forego some normal life activities during childhood or as adults, such as participating in contact sports, and these lifestyle restrictions can have a significant effect on emotional well-being. “These patients worry a lifetime about what might have been, what should have been done and what will not happen as a result of their blindness,†Dr Aclimandos said.

Dr Aclimandos emphasised there is an element of urgency because children with amblyopia who do not receive treatment during the critical period are condemned to blindness forever. The plan for action is multifaceted. It includes greater training of local eye care practitioners who can conduct appropriate vision screening and of personnel able to perform refractions and prescribe glasses. In addition, funding is necessary to pay for glasses to correct high refractive errors or aphakia after cataract surgery. “However, the needs do not stop there because followthrough and infrastructure are also required to make sure children receive replacement glasses if theirs are broken, lost or the prescription changes,†Dr Aclimandos said. Even then, there is more that can be done to help those who were unfortunate enough to slip through the cracks and wind up visually impaired. These individuals can be helped by registration programmes, referral to visual impairment educationalists, support groups and interventions to address cosmetic concerns. “Interpersonal interactions are essential for normal childhood development and may be adversely affected, even within the family, for a child with cosmetic issues associated with visual impairment,†Dr Aclimandos explained.