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When to Screen? 2.4.1

Treatment Outcome and Age

For many years, there has been a general belief among ophthalmologists that early detection of amblyopia gives better treatment outcome. Recent studies have shown contradictory results.

Williams et al. [50] compared an extensive program with orthoptist examinations on six occasions from age 8 months to age 37 months, with one orthoptist examination at age 37 months. Results showed that children subjected to the intensive screening protocol had a lower prevalence of amblyopia at age 7.5 years. Interestingly, more than half of amblyopic subjects in the intensive groups were found at 37 months, despite five previous examinations. A major drawback of the study is the large number of dropouts at the final examination; only slightly more than half attended at age 7.5 years, which makes the representativeness of the results questionable.

In two studies by the US-based Pediatric Eye Disease Investigator Group on moderate ambly-opia (VA 0.2-0.5) in children aged 3-7 years, no association was found between age and treatment effect [38,39]. In a study on severe amblyopia (VA 0.05-0.2) by the same group [18], no significant age effect was found when compar ing all age groups, but when pooling data and comparing younger children (<5 years old) to older children (5 to <7years old), a significant age effect was found with a larger improvement in younger children.

In a study of children aged 3-5 years, Clarke et al. [9] found no negative effect when treatment was delayed until age 5 years. Surprisingly, their data even showed that deferring treatment nearly halved the proportion of children needing patching treatment at all.

Results from the Monitored Occlusion Treatment of Amblyopia Study (MOTAS) [46] found a significant difference in improvement of visual acuity following occlusion with greater improvement for age less than 4 years, compared to age 4-6 years and over 6 years.

All in all, the results indicate a possible small age effect with better outcome for children younger than 4-5 years of age.

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