Cataract Research by HMC Team Debunks Current Standards

What began as a Harvey Mudd College investigation into a statistical hunch culminated in a late-August research presentation in Mombasa, Kenya that debunked World Health Organization (WHO) cataract surgical rate (CSR) targets. The WHO uses CSR targets to measure the number of cataract surgeries per million people needed to prevent cataract-related blindness.The Harvey Mudd team that delivered the information included mathematics professor Talithia Williams and alumni Brian Stock ’09 and Susan Lewallen ’76. Lewallen, who headed the project, co-directs the Kilimanjaro Centre for Community Ophthalmology (KCCO), a public health institution in Tanzania.The inquiry began as the result of a growing awareness that, in spite of training programs and provision of health care services, ophthalmologists in Lewallen’s area were not reaching CSR targets set out by the WHO. Although they fell short of their goals, clinics were nevertheless treating a large number of people with cataracts. According to recent surveys, a staggering 70 percent of cataract patients received services in the Kilimanjaro Region despite the area’s CSR of 1,000 per million people—less than one-fourth that of most developed countries.The team realized that surgeons were doing a lot of unnecessary work. With the support of her colleagues, Lewallen set out to attain statistical evidence for her hypothesis, enlisting the help of Williams and Stock and providing them with data that had been previously collected by her colleagues in various countries.“When I first applied to work with professor Williams, this specific project was not fleshed out,” Stock said. “Then professor Williams met with [Lewallen], who came up [with] what she thought we could do to help her. She gave us survey data, and I wrote a computer code using a previous paper published on how to calculate incidence from prevalence and ran it on the numbers.”The results of the calculations showed that the CSR targets should be lowered, aligning with the suspicions of surgeons in Tanzania. These numbers, including methods used, results, and assumptions, were presented to a group of eye surgeons and individuals who had been integral to the project.“My colleagues in Eastern Africa are very pleased and feel vindicated I think,” Lewallen said. “But it is likely there will be people who will question our work. We’ll have to be prepared to defend our findings.”Lewallen continued that the team’s next step will be to publish their findings in order to make the data more widely available.“I believe we are correct, but it is important to be able to convince other scientists,” she said. “Publication in a peer-reviewed journal will be the first step. Then, in the many courses KCCO teaches on eye care service planning in Africa, and the programmers we mentor though the planning process, we will use the new targets.”While Harvey Mudd has been proactive in providing students with ample research opportunities and making connections between interested professors and students, Stock admits that his was a unique opportunity that exceeded his expectations.“I’ve thought about and considered public health and working with epidemiological modeling as a career, and this made it seem exciting,” Stock said. “I just came in and did my little piece and the whole project was more than just my contribution. [But] people don’t usually do this after graduation.”

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