ArticlesRetinopathy of prematurity in middle-income countries
Introduction
Retinopathy of prematurity (ROP) became the major cause of blindness in children in Europe1 and North America during the late 1940s and 1950s after the introduction of intensive neonatal care with unmonitored supplemental oxygen for preterm and low-birthweight babies (the “first epidemic”). Since then, increased awareness of the importance of monitoring blood gases has resulted in a lower incidence of potentially blinding ROP, except in extremely low-birthweight babies, less than 1000 g at birth—ie in whom the “second epidemic” is occurring. Data from industrialised countries suggest that up to 8% of extremely low-birthweight infants become blind from ROP.2, 3
A multicentre clinical trial of peripheral retinal cryotherapy for threshold, Stage III plus disease showed the effectiveness of this treatment. Progression to retinal detachment in acute cases was almost halved, and at 5 1/2-years follow-up there was a 24% reduction in poor visual outcome in treated eyes compared with untreated eyes, and a 41% reduction in poor structural outcome.4 As a result of improved intensive neonatal care, and screening and treatment of threshold disease in preterm, low-birthweight and extremely low-birthweight babies, ROP now accounts for 6–18% of registered blindness in children in industrialised countries and is no longer a major cause of blindness.5, 6, 7, 8, 9, 10 Population-based data on the causes of blindness in children, which would allow accurate monitoring of trends, requires either compulsory blindness registration, comprehensive surveillance systems, birth cohort studies, or large population-based longitudinal studies. Such information is difficult to obtain from developing countries, and many such countries outside Europe do not have blindness registers. In these circumstances, examination of children enrolled in special education can provide data on the causes of blindness.
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Participants and methods
Between 1991 and 1996, studies in schools for the blind were undertaken in 23 countries in four regions of the world by nine ophthalmologists (table). In each study, standard definitions, methods of examination, proformas, and statistical packages were used. Medical records were reviewed when available, and additional information on past medical history and family history was obtained from teachers and parents, if available.
Visual acuity was measured in each eye with a Snellen E chart to
Results
Data for 4121 children with SVI/BL and the proportion due to ROP in each country are shown in the table.12, 13, 14, 15, 16, 17, 18, 19, 20 In all African countries, except South Africa, there were virtually no children with SVI/BL from ROP. Retinopathy of prematurity was responsible for 0–16·9% of SVI/BL in Asian countries, 0–25·9%% in eastern European countries, and 4·1–38·6% in Latin America.
The figure shows the proportion of SVI/BL due to ROP in each country plotted against the infant
Discussion
In some countries, not all children with SVI/BL have access to special education, and facilities for blind children with additional disabilities may also be limited. In countries with low levels of health-care provision, blind children with additional handicaps are likely to have higher mortality rates than blind children who are otherwise normal. Data to support these assumptions are, however, difficult to obtain. Children blind from ROP often have other disabilities2 such as cerebral palsy,
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