Getting down to business: Starting the Rwandan RAAB
Once the program started it was “all business”, as they say. The focus of group who had come together to accomplish this task was palpable. Dr. Ciku began the training as if holding court. She had a strength of presence that was unmistakable. As she spoke, the room was infused with her sense of purpose. She was unwilling to accept anything but the hardest work and the greatest dedication. She had the uncanny ability to make each individual want to rise to the occasion. The first two days were 8 hour “classroom” days of learning about the RAAB (Rapid Assessment of Avoidable Blindness).
So, what exactly is it? What makes it “rapid”? This assessment was the brainchild of a physician named Hans Limberg. The assessment was modified from its original version (which was created to evaluate and address the presence of cataracts specifically) to a version that is used to survey generalized impairment of functional vision. This is a population-based survey, in which the country is scoured border to border in order to obtain a representative sample. The current healthcare plan regarding eye health is based on data extrapolated from the WHO, and not specific to Rwanda. While it may seem harmless and even logical to use data extrapolated from nearby countries with similar climates, smaller studies have proven that these countries can have differing causes of visual impairment. For example, a study performed in Kenya found the major causes of blindness to be cataract followed by corneal blindness, but this study was performed in areas where trachoma is endemic. This is not the case in Rwanda, and therefore, corneal blindness will likely contribute to visual impairment far less in Rwanda than what is currently quoted by the WHO. In fact, a smaller RAAB performed in 2006 in just the Western province of Rwanda found that cataract and glaucoma were the two major contributors to blindness. This nationwide RAAB will allow for evidence-based planning when determining how to allocate funding toward eye health.
A RAAB simplifies the population-based survey by limiting the participants to those over the age of 50, since most visual impairment occurs in this population. Each RAAB is performed in the exact same way. It utilizes a very basic ophthalmic exam, and can be performed by trained local staff. The RAAB uses specialized software that calculates the appropriate sample size, performs a random selection of “clusters”, and has inter-observer variation assessment capabilities. Despite the simplicity in its design, the RAAB answers many very useful questions within a population. It provides information about the prevalence of blindness and its causes, and the prevalence of cataract blindness specifically. The study also assesses cataract surgery coverage within the country, including how much low vision results, and potential causes of poor outcome.
For this first national Rwandan RAAB, we will be examining 5,000 patients over 26 days. Each “cluster” selected will have a population of 3,000-5,000 individuals, based on the most recent census data. Once a “cluster” is selected, a “cluster informer” goes to the village and informs the executive secretary (which is an appointed government official for the village) about the study and our intention to evaluate members of his community, and obtains consent from him on behalf of the citizens. The executive secretary, in turn, assigns a village guide and a time is arranged for a meeting place on the selected date of survey. The goal is to obtain 50 participants. Usually, the guide is asked to draw the village, which is then divided into equal sections based on the population of the village. The team focuses on that single section until 50 people over 50 have been evaluated. In Rwanda, villages are naturally broken up into sections, called “Umudugudus”. So rather than create arbitrary sections, we will ask the guide to pick a random Umudugudu within his village, and we begin going door to door in that location, covering all homes until we have obtained 50 participants or we have covered each home within that Umudugudu. If we have not reached our goal, we will pick another umudugudu within the same village.