Understanding how scientific research maps to the drivers of burden can help us understand how current research priorities roughly map to areas of economic consequence. To develop a measure of scientific volume, I compiled PubMed search results related to the visual sciences and used these results to estimate the number of articles in each general visual health condition area. I then compared research volume to drivers of direct medical costs as estimated in the PBA study.
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To do so, I first created a list of search terms associated with the topic areas of “Cataract,” “Glaucoma,” “Ocular Physical Disorders,” “Other Vision Problems,” “Refractive Error,” “Retinal Disorders,” and “Vision Problems and Blindness” (
Supplementary Appendix A), and their associated Medical Subject Headings (MeSH), and created an inclusive search for articles referenced by PubMed using these terms over the last five years (July 5, 2008 to July 3, 2013). This search resulted in an aggregate total of 134,582 articles related to visual science over the last five years. A cursory quality check of these results indicated that, while a few references were tangential or unrelated, the majority of articles did include some reference to or research regarding a visual science topic. As a further limitation, this search likely also omitted some relevant articles that were not captured directly by one of the search terms. However, given the review and commentary nature of this article, this study accepted the list of 134,582 articles as an adequate, if rough, measure of visual science research priorities over the last five years.
To allocate these articles to individual conditions, I next searched within this restricted list to identify the number of articles that referenced each condition. Article identification was not mutually exclusive in that a single article could be counted in more than one topic area if it contained references to multiple condition categories. This generated a list of the aggregate number of articles that discussed each condition area over the last five years (
Table 1). Following article identification, the number of articles in each topic area was divided by the total number of articles identified using all terms to identify the percentage of total articles in which the topic was mentioned.
Table 1 compares each visual condition's percentage contribution to direct medical costs to its percentage contribution to scientific articles over the last five years.
Table 1 also shows the ratio of the percentage of articles to the percentage of direct medical costs. When viewed in this manner, the areas of refractive error and cataract generated a lower proportion of scientific articles compared to what would be expected if articles were driven purely proportionally by direct medical costs. Likewise, the areas of retinal disorders and glaucoma generated a larger proportion of articles as did “Other vision problems,” which included all ocular research other than the visual disorders listed. Vision problems and ocular physical disorders generated articles in proportion to their burden.
This rough measure is descriptive in nature and is not meant to be taken as a proscriptive recommendation to study more or less in certain areas. Studies directed toward the retina, the causes of glaucoma, and the functioning and impairment of the optic nerve represent fundamental areas of remaining mystery in the visual sciences. Unlocking the secrets of these systems may result in paradigm shifting breakthroughs in our understanding of vision, aging, and cognition. At the same time, the results are suggestive that certain areas of visual dysfunction may warrant additional attention. Also clear is that the indirect consequences of visual disorders often are overlooked within these articles on visual health. For example, searching within the 134,582 articles for the term “Rehabilitation” resulted in 3191 articles, searching within these articles for “Productivity” resulted in 1935 articles, and searching within these results for “Long Term Care,” “Nursing Home,” or “Skilled Nursing Facility” resulted in only 670 articles.