The decision about when to prescribe for astigmatism and how much, can be a little bit fuzzy at times. This is particularly true when considering the various schools of thought about what astigmatism signifies. Is it merely a refractive error to be “corrected” optically, or does it signal an adaptation of the visual system? Is it adaptive and purposeful on a cortical level, or is it a sign of a maladaptive shift in visual function? My co-author Dr. Werner and I probed some of these questions in our textbook, and a new study published in the Academy journal this month adds to the intrigue.
The March 2012 issue of Optometry and Vision Science carries the article, Effect of Simulated Astigmatic Refractive Error on Reading Performance in the Young. The paper has seven co-authors, all from the School of Optometry and Institute of Health and Biomedical Innovation at Queensland University of Technology in Brisbane, Australia. The performance metrics used in the study were changes in the Discrete Reading Rate (DRR), the Developmental Eye Movement Test (DEM) and in the Visagraph III. The stated conclusion is that induced astigmatism impaired performance on selected tests of reading fluency, with against-the-rule astigmatism having significantly greater effects on performance that with-the-rule, even for relatively small amounts of astigmatic blur of one diopter. They suggest that these findings have implications for the minimal prescribing criteria for astigmatism.
I suggest you get a hold of a copy of the paper and read it beginning to end. At the very least, it will make for some nice discussion between ODs specializing in developmental vision and our primary care optometric colleagues. It may also spark some lively conversation among practitioners involved in the reading field. You may be surprised by some of the difference among the reading performance tests and measures used here, and the interpretation about the effect of astigmatism on reading fluency.
– Leonard J. Press, O.D., FCOVD, FAAO