Measuring the impact of cataract services in the community

How can RAAB be used to improve cataract services? RAAB is a method for rapidly assessing visual acuity.2 People aged 50 years and above are randomly selected from a population. They undergo visual acuity screening and those who are found to have problems with their vision are examined by an eye care professional to determine the most likely cause. To date, more than one hundred RAAB surveys have been conducted to date across the world. Information from RAAB surveys can be used to improve cataract services in a number of different ways. RAAB provides estimates of the prevalence of blindness and visual impairment and its main causes. This information can be used to estimate the need for cataract surgery in the community. From this, we can estimate the number of cataract operations that need to be performed per million population per year (known as the cataract surgical rate) in order to help everyone who needs a cataract operation within a set time frame. Information is also collected on the number of people who have undergone cataract surgery; this can be used to estimate cataract surgical coverage (i.e. the proportion of patients/eyes with operable cataract who have already received surgery), which is a measure of progress. Where no hospital data are available, RAAB survey findings about the visual acuity of people who have undergone cataract surgery can be used to give an overview of the quality of cataract services in an area or district. The causes of poor visual acuity can also be used to identify areas for improvement. For instance, if poor outcome after cataract surgery is common and is attributable to refractive error, then better optometry services may be needed. The RAAB data on quality will not be as good as hospital data in reflecting current outcomes, because RAAB will include people operated on many years ago and from a variety of different surgical services. During RAAB, people who have cataract but have not undergone surgery are asked why they have not attended. This information shows us the main barriers to overcome when providing services in an area. For instance, if cost is cited as the main barrier then the service could consider providing subsidies, whereas if lack of awareness is the main barrier then a publicity campaign may be needed. Finally, RAAB can also be used to monitor the impact of a cataract surgery service if it is repeated after a period of time (e.g. 5–10 years) and the prevalence and causes of visual impairment at the two time points compared.