In what researchers say is the largest such study to date, physician-scientists have found that the risk of blindness caused by spinal fusion has dropped almost three-fold since the late 1990s. The study was published online June 30, 2016 in Anesthesiology. Steven Roth, M.D., the Michael Reese Endowed Professor of Anesthesiology at the University of Illinois at Chicago College of Medicine, was a senior author on the paper.
“We wanted to know if rates of blindness as a result of these surgeries was stable, increasing or decreasing over time, ” said Dr. Roth in the June 30, 2016 news release. Dr. Roth is also professor of ophthalmology at UIC.
The researchers used data from the Nationwide Inpatient Sample, and estimated that 2, 511, 073 spinal fusions were performed, resulting in 257 instances of ischemic optic neuropathy, or 1.02 per 10, 000 surgeries. But over that time-span, the risk decreased 2.7 fold, or 60%.
As indicated in the news release, “The researchers noted that significantly increased risk for ischemic optic neuropathy during spinal fusion surgery came with age over 50; male sex; receiving a blood transfusion during the procedure; and obesity. Dr. Roth believes that changes in anesthesia practice may also be driving the decrease in risk of blindness. Many anesthesiologists now set a stricter limit for how low they will allow blood pressure to drop during surgery, he said, which may help reduce the risk for ischemic optic neuropathy.”
“The characteristics of the patients undergoing spine fusion haven’t changed all that much over the years, although the population has aged, ” Dr. Roth said. “So the variables that must be contributing to the decline in blindness caused by spine fusion surgery are most likely the result of changes made in how the surgery is performed.”
Dr. Roth told OTW, “We did not expect the incidence of perioperative ION (ischemic optic neuropathy) to be going down as dramatically as it turned out. We are encouraged by these results, because it means this complication is, while not gone, much less frequent than it has been in the past. Also, we were surprised to learn that increasing age is a risk factor. Previous studies did not show this result.
“These results are very helpful for predicting the high-risk patient and for delivering an informed consent. Based this study, and our previous one in Anesthesiology in 2012, the highest risk patient for spinal fusion can be predicted in advance as one who is a man, obese, elderly, scheduled for a long procedure and/or expected large blood loss, and is to be positioned on a Wilson frame. These patients should be advised of the risk of visual loss, and it should be seriously considered if the Wilson frame is necessary. Moreover, the surgeon should consider staging if the procedure is going to be prolonged and associated with significant blood loss.”
Dr. Daniel Rubin of the University of Chicago is the first author on the paper. Isaac Parakati of the University of Chicago; Dr. Lorri Lee of Vanderbilt University; and Drs. Heather Moss and Charlotte Joslin from the department of ophthalmology and visual sciences at UIC are co-authors.
