Myopia and eye disease: From correlation to causation

Area of Science:

• Ophthalmology and Public Health
• Epidemiology
• Genetics

Background:

• Myopia is increasingly recognized as a major risk factor for visual impairment and serious ocular diseases.
• The causal link between myopia and these secondary conditions is crucial for understanding the public health value of myopia control.

Purpose of the Study:

• To evaluate the causal role of myopia in associated ocular diseases using Bradford Hill's nine criteria.
• To assess the evidence supporting myopia management as a public health strategy.

Main Methods:

• Systematic review of epidemiologic, longitudinal, mechanistic, interventional, natural-experiment, and genetic studies.
• Application of Bradford Hill's criteria for causality assessment (strength, consistency, specificity, temporality, biological gradient, plausibility, coherence, experiment, analogy).

Main Results:

• Strong dose-response relationships observed between myopia severity (refractive error, axial length) and risks of visual impairment, myopic maculopathy, and rhegmatogenous retinal detachment.
• Consistent, though more modest, associations found with primary open-angle glaucoma, supported by longitudinal and genetic data.
• Subtype-specific links to cataract, particularly posterior subcapsular cataract; evidence for nuclear cataract is less clear.
• Strong biological plausibility and coherence demonstrated through the effects of axial elongation on ocular structures.
• Convergent evidence across all criteria supports causality.

Conclusions:

• The evidence strongly supports a causal role for myopia in major myopia-associated ocular diseases.
• Myopia management is justified as a strategy to mitigate lifetime axial elongation and reduce the risk of sight-threatening conditions.