# Augmented Reality in Surgical Navigation: A Review of Evaluation and Validation Metrics
###### Abstract  
Pre-operative imaging has been used earlier to guide traditional surgical navigation systems. There has been a lot of effort in the last decade to integrate augmented reality into the operating room to help surgeons intra-operatively. An augmented reality (AR) based navigation system provides a clear three-dimensional picture of the interested areas over the patient to aid surgical navigation and operations, which is a promising approach. The goal of this study is to review the application of AR technology in various fields of surgery and how the technology is used for its performance in each field. Assessment of the available AR assisted navigation systems being used for surgery is reviewed in this paper. Furthermore, a discussion about the required evaluation and validation metric for these systems is also presented. The paper comprehensively reviews the literature since the year 2008 for providing relevant information on applying the AR technology for training, planning and surgical navigation. It also describes the limitations which need to be addressed before one can completely rely on this technology for surgery. Thus, additional research is desirable in this emerging field, particularly to evaluate and validate the use of AR technology for surgical navigation. augmented reality; surgery; visualization; evaluation; validation +
Footnote †: journal: Medical  
MRI data and to overlay virtual images over a view of the surgical field. AR technology, in general, consists of 3D reconstruction, display, registration, and tracking techniques, and it has been recently used in surgical interventions. Consequently, AR technology can combine the pre-operative model with the intra-operative scenario, giving clinicians real-time information and surgical guidance [8]. Until recently, AR navigation technology has been widely employed in various fields of surgery, including neurosurgery [9; 10; 11; 12; 13], orthopedic and spine surgery [14; 15; 16], laparoscopic surgery [17; 18], hepatobilary surgery [19; 20; 21; 22; 23; 24], oral surgery [25; 26], etc. [27; 28; 29]. The goal to do brain surgery as minimally invasive as feasible may be seen throughout the entire history of neurosurgery. The reason for this is that neurosurgery is the practice of performing surgery on or within an organ that contains many sensitive regions that have a direct impact on a patient's mental and physical well-being. As a result, neurosurgeons frequently accept new technology before others do, with the hope that it may reduce surgical risks and improve patient outcomes. Similarly, researchers have explored using AR technology for image guided surgery in various other fields to overcome surgical complexities by enhancing the operating room (OR) with virtual content. The application of AR systems in different surgical fields and their performance is described in the next section. In Section 3, the evaluation pertaining to surgical techniques used in AR are described and some validation techniques have been suggested. The last section discusses the limitations of this technology in the surgical field and how the AR navigation systems can be improved so that it can prove to be beneficial for the society in the near future. For this study, many recent papers have been reviewed especially concentrating on articles published after 2008, since the adoption of AR technology began to rise in many surgical fields around that time. Our search criteria involved mainly the following keywords (but not limited to): augmented reality, evaluation, assessment, validation, surgery, etc. at the e-resources platform available within our university's research collection. Figure 1 shows the distribution of the chosen papers taken into consideration for this study by year. The last search was conducted in May 2022 which explains the drop from 2021, although the dotted curve showing the trend-line over the years shows an exponential growth.