Amblyopia and the Public Health Data Gap: Why a Treatable Childhood Vision Disorder Can Remain Invisible to Health Systems

Amblyopia is a common, treatable disorder of childhood visual development, yet health systems that deliver vision screening and treatment may still be unable to say how many children are affected, who was never reached and what happened after diagnosis. This evidence-informed public-health perspective defines the amblyopia public health data gap: the difference between the information health systems routinely collect about childhood vision services and the population-level information needed to determine who is affected, who remains unseen, what outcomes are known and whether the burden is changing. It argues that screening coverage, prevalence, diagnostic yield and treatment outcomes answer different questions and require different denominators; that a failed screen or an amblyogenic risk factor is not a diagnosis, and a diagnosis is not an outcome; and that missing records should be reported, not silently dropped. Drawing on published evidence from Scotland, the United Kingdom, the United States and the Netherlands, and on WHO eye-care monitoring guidance, it proposes a six-stage conceptual hierarchy for amblyopia population measurement: define the population, measure ascertainment, confirm cases, characterise burden, ascertain outcomes and examine population trends. The hierarchy is conceptual and has not been prospectively validated.