Taylor et al writing in this issue of the BJO (p 272) are to be congratulated for their excellent description of the economic burden of visual impairment in Australia. While most in the eye care community have always assumed that visual impairment represents an important social burden, the authors have shown that the absolute economic burden of visual impairment ranks with cancer, dementia, and arthritis. The impact relative to the entire Australian economy (0.6% of the Australian GDP) also emphasises the non-trivial nature of the burden of visual impairment. The results should catch the attention of health policy makers because they suggest that, even in a developed economy, visual impairment can limit further economic development.

In order to make appropriate use of the important findings, readers must understand the inputs into the burden calculation, the way in which a measure of burden can fit into cost effectiveness or cost benefit models, and notable points about the methods used. Epidemiological and economic data are inputs for a national burden calculation. The epidemiological information is either prevalence or incidence; Taylor et al used prevalence, and this has implications for how the results can be incorporated into an economic evaluation. The economic data include expenses related to prevention and treatment of conditions leading to visual impairment, productivity loss among the visually impaired population, and expenses attributable to informal care. The inputs suggest that in the absence of vastly improved methods of preventing the incidence or progression of cataract, glaucoma, age related macular degeneration, and diabetic retinopathy, the national prevalent burden will grow over time in ageing populations unless the economic costs per person are …