Table 1.

Summary of the PICOS elements for the systematic review of studies reporting costs associated with VI and its major causes.

Participants	Included: Participants with VI from an unspecified cause or due to one of the leading causes of VI globally (i.e. cataract, uncorrected refractive error, diabetic retinopathy, glaucoma, AMD, corneal opacity or trachoma).12
Interventions	Included: Studies reporting services for cataract were included regardless of VI as this tends to be a one-off intervention and the cost of treatment does not vary with the severity of vision loss. Studies reporting services for refractive error were included regardless of VI as these tend to be a series of irregular one-off efficacious interventions. Excluded: Studies that reported costs of screening or treatment services for the remaining causes of VI that did not report costs for people with VI.
Comparators	Not relevant
Outcomes	Included: Studies reporting any of the following outcomes among people with VI: Direct costs, indirect costs, productivity losses (e.g. absenteeism costs, lost work days, employment opportunities), informal care (e.g. caregivers costs, number of caregivers hours), intangible costs (e.g. QALYs, DALYs), transfer payments or deadweight losses. Excluded: Studies that only reported incremental costs, net costs, incremental benefits or net benefits, incremental cost effectiveness ratio, incremental cost benefit ratios without also reporting actual costs.
Study Design	Included: Partial economic evaluation studies such as cost of illness studies, burden of illness/diseases and full economic evaluation studies such as cost-effectiveness and cost-benefit studies. Excluded: Model-based economic evaluation studies not reporting any costs, primary data or based on reviews of existing studies.

VI: Vision impairment; AMD: Age-related macular degeneration; QALYs: Quality adjusted life years; DALYs: Disability adjusted life years.