Epidemiology and visual impairment

World Health Organization data from 2010 estimated that approximately 285 million people across the world had some form of visual impairment (Pascolini & Mariotti, 2011). In 2017, a new review of the data by the Vision Loss Expert Group and published in The Lancet Global Health estimated that there were 253 million people with visual impairment in 2015 (Bourne et al. 2017).

90% of visually impaired people are in low and middle-income countries. Strengthening services, improving access, and addressing inequity at the local level are an urgent priority for global eye care. Prevention programmes are essential to achieve these goals and reduce the burden of visual impairment across the world.

In this step we use the 2010 data to introduce the epidemiology of blindness and visual impairment, looking at four key concepts:

• Magnitude – how many people are affected?
• Distribution – where is it?
• Determinants – what are the main causes?
• Control – what can we do about it?

Try to consider the main causes of visual impairment in your own community and the control strategies that local eye care programmes carry out.