A Survey of Incidence of Postoperative Visual Loss Associated With Spine Surgery Outside the United States
Postoperative vision loss (POVL) is a rare but serious complication, associated with the prone position during surgery.1 Although the prevalence is low, the poor prognosis associated with this condition prompted the American Society of Anesthesiology (ASA) to issue a practice advisory in 2006, which was updated in 2013.2 There is thus widespread awareness of POVL as a serious risk in the United States, where it is increasingly becoming part of the informed consent for prone procedures. In contrast, a review of the literature in countries of equal income and equivalent medical practices does not reveal a similar concern. The question thus remains whether POVL is a worldwide issue, or whether peculiarities in the US patient population make American patients more prone to this particular complication, such as the nationwide obesity epidemic, with the concomitant increase in diabetes and cardiovascular disease. A survey was conducted where we contacted prominent medical personalities in Australia, Belgium, Canada, Germany, France, Italy, Japan, and the United Kingdom to find the incidence of POVL outside the United States. Most are members of the Society for Neuroscience in Anesthesiology and Critical care (SNACC) and also had strong Neuroanesthesia societies able to support this endeavor. The survey had 15 questions, establishing first the level of experience of each responding anesthesiologist, and how often they dealt with spinal surgery. We asked if they had witnessed at least 1 episode of POVL. We queried positioning, head holding devices, type of table used, patient population characteristics such as age and BMI, average time on the prone position, and thresholds for blood transfusion and blood pressure management, factors which may impact the incidence of POVL.3 It is important to note that each respondent commented on his or her lifetime experience, rather than on a specific patient case or cases, and the data we collected on occurrence of POVL thus summarizes the respondent’s lifetime experience. This approach was chosen for practical reasons. The primary aim was to determine if POVL occurs outside of the United States, rather than obtain accurate prevalence estimates. This report focuses on 810 responses (out of 927 received) from 9 geographical regions. A total of 42 respondents of 810 (5.2%) answered that they had personally witnessed a case of POVL. Overall, these 810 respondents estimated that they had performed a total of 194,640 complex prone cases in their lifetime. Then, a rough estimate of the prevalence of POVL outside of the United States is 0.021%—slightly higher than, but remarkably close to, all things considered, the estimates of 0.016% and 0.013% in Roth et al4 and Holy et al.5
This survey shows that POVL is not solely an American problem, indicating a need to inform providers worldwide. Our crude estimate of POVL prevalence outside of the United States is very close to those reported in recent large-scale retrospective studies in the United States.4,5 In the short term, the best approach remains a reasonable use of the ASA 2013 practice advisory, and the recommendations on informed consent issued by the Anesthesia Patient Safety Foundation2 that include discussion of POVL risk factors that may increase patient and physician awareness. The fact that the ASA had taken measures to study the problem and “to enhance awareness and reduce the frequency of perioperative visual loss”2 clearly shows that US physicians have considered this a serious health issue for a number of years. Yet, if practitioners outside the United States are clearly aware of the problem, their national societies have not yet considered that the risk of POVL warrants specific recommendations.