They also include presbyopia, a normal ageing change, where the eye is no longer able to focus at close range.
These eye disorders can be particularly problematic in developing countries, where those affected may not be able to afford sight tests or spectacles to help improve their vision. What’s more, those living in rural areas may not have access to eye care – in sub-Saharan Africa, for example, two-thirds of ophthalmologists and optometrists are based in capital cities, leaving a shortage of trained eye care professionals working in rural areas.
The patient is given an eye test to find out how badly their vision is affected.
During the test, they're asked to read letters or symbols from a chart.
If they have refractive error, it can then be corrected with spectacles.
We have also helped to train 732 optometrists and 433 optometric technicians, who are able to carry out sight tests, diagnose eye problems and help to treat people with low vision in some of the poorest parts of the world, who may otherwise not have access to eye healthcare.
Sightsavers’ School Health Integrated Programming (SHIP) project, which ran throughout 2016, screened schoolchildren in Cambodia, Ethiopia, Ghana and Senegal for health problems such as poor vision.
As part of the project, teachers were trained to carry out basic eye tests and refer children for further treatment. During the project, 57,400 children were screened for eye problems and 1,000 were given spectacles.
Download Sightsavers refractive error strategy (pdf) to read more about our work to treat refractive error.
For children such as Riya, something as simple as a pair of glasses can mean the difference between a bright future and being trapped in a cycle of poverty.
Read her storyThe transgender community often experience discrimination and lack access to healthcare. Meet some of the people who benefited from an eye health screening.
In Sierra Leone, children with disabilities are often considered not worth educating. We've worked with schools to make sure these children are not left behind.
We caught up with healthcare professionals at an eye hospital in Dhaka, Bangladesh who were trained more than a decade ago as part of the Seeing is Believing project.