A librarian collaboratively developed the search strategies with the senior author (SB) and ran searches in the following databases in April 2017: PubMed MEDLINE, Embase, Cochrane Central Register of Controlled Trials on the Wiley platform, Cumulative Index to Nursing and Allied Health Literature, PsycINFO (EBSCO), and IEEE Xplore. Search strategies for all databases were adapted from the PubMed MEDLINE strategy. Searches were conducted in all databases back to 2013, which is the year that Google Glass was first released. No language limits were applied. The search strategy specified keywords related to Google Glass (see Multimedia Appendix 2 for complete search strategies in each database). We also conducted a hand search for additional related articles in the Journal of Medical Internet Research and by searching the reference lists of key studies and relevant systematic reviews.

The inclusion criteria required (1) original research articles; (2) studies that were randomized controlled trials, quasi-experimental studies, or pilot/feasibility studies; (3) Google Glass interventions; (4) studies conducted under surgical settings (preoperative, intraoperative, and postoperative); and (5) studies in clinical settings (real time or simulated). We categorized articles based on different stages or settings related to the surgical process, including the time spent preparing for surgery (preoperative setting), time spent during surgery (intraoperative setting), and time spent recovering from surgery (postoperative settings). The exclusion criteria were applied for (1) studies using technology-based interventions other than Google Glass; (2) nonsurgical setting studies; and (3) articles with more technical description of Google Glass but no clinical, usability, feasibility, and/or acceptability outcomes.

We utilized a standardized form for data extraction that included the following items: authors’ names, publication year, country in which the study was performed, surgical application of the study, purpose of the study, description of Google Glass as a surgical intervention, participant demographics (age and sex when available), sample size, study design, results, limitations, and other study considerations. Two authors (NW and AM) screened all articles individually. Discrepancies were resolved through discussion with the senior author (SB) whenever necessary. Data were analyzed quantitatively and qualitatively.

A total of 520 citations were retrieved through a literature search in five different databases. After removing duplicates, 380 original articles remained for screening (Figure 1). Two authors (NW and AM) independently screened the article titles and abstracts of 380 records against the inclusion criteria and a total of 78 records met all predefined inclusion criteria. Two authors (NW and AM) then independently reviewed the full text of these articles against the exclusion criteria, and 47 articles were excluded. A total of 31 articles met all predefined criteria to be included in this review. We did not identify any non-English articles that met our predefined criteria. The study flowchart and reasons for exclusion of full-text articles were documented and summarized in an adapted PRISMA study flowchart (Figure 1).

A summary of the 31 included studies and their Google Glass applications can be found in Table 1. Of the 31 studies, 23 (74%) were conducted in the United States [12-34], three in the United Kingdom (10%) [35-37], and one in each of Spain (3%) [38], Canada (3%) [39], Switzerland (3%) [40], China (3%) [41], Australia (3%) [42], Mongolia (3%) [19], and Brazil and Paraguay (3%) [18]. Of note, two studies from developing countries were in collaboration with researchers from the United States [18,19]. All included studies were conducted in hospital settings; 29 (94%) in adult hospitals [12-26,28-41] and two (7%) in children’s hospitals [27,42]. Sample sizes of participants who wore Google Glass ranged from N=1 to N=40. In all, 25 of 31 studies (81%) were conducted under real-time conditions or actual clinical care settings [12,14-16,18-20,23-38,40,42], whereas the other six (19%) were conducted under simulated environments [13,17,21,22,39,41]. In addition, 26 studies (84%) were pilot or feasibility studies [12,13,16-21,23,25,26,28-42], three (10%) were case studies [14,15,27], and two (6%) were randomized controlled trials [22,24].

The vast majority of the studies examined the potential use of Google Glass as an intraoperative intervention (27/31, 87%) [12-31,35-42], whereas others observed its potential use in preoperative (4/31, 13%) [19,27,32,33] and postoperative (5/31, 16%) [15,19,27,30,34] settings. Only a few studies evaluated the use of Google Glass in more than one of these settings (4/31, 13%) [15,19,27,30]. In many cases, multiple functions and applications of Google Glass were tested in a single study. Of the two involving pediatric patients, one study required consent given by the patients’ parents or guardians, and all recordings were shared with them as requested [27]. In the other, Google Glass was not connected to the hospital network or Internet, and no recordings were made [42].

In all studies, Google Glass was worn exclusively by a medical professional, including nurses, physician assistants, medical school students, medical residents (postgraduate years 1 to 5), attendings, or simulated health care professionals. Reporting of provider demographics varied across all studies. Three studies reported age data of health care professional participants: one reported a range of 27 to 31 years [40], one reported a mean of 29.7 years [22], and one reported a mean age of 28.4 years with a range of 18 to 50 years [39]. Two studies reported health care professional sex information: one study had a participant pool that was 14.3% (1/7) female and 85.7% (6/7) male [40] and the other reported a sample that was 100% (12/12) male [39].

Reporting of patient demographics was largely limited across all studies. Only two studies provided patient age data: one included a sample of participants with a mean age of 70.6 years [26] and the other was a case report of a patient who was 66 years [14]. Two studies reported patient sex information: one reported a participant sample that was 58% (69/120) male [26] and the other reported one male patient (1/1) [14]. None of the studies reported race or ethnicity information.

Table 2 summarizes the goals and intervention details of each study. Six studies utilized Google Glass’s heads-up display as a vital sign monitor to facilitate improved patient monitoring and maintain attentiveness to the surgical field (6/31, 19%) [22,25,35,40-42]. Five studies (5/31, 16%) used Google Glass as a surgical navigation display to visualize ultrasound and fluorescence imaging data (3/5, 60%) [13,24,41], to visualize electromyography data (1/5, 20%) [36], and to position placement of tools on the body (1/5, 20%) [39]. Five studies used Google Glass as a videoconferencing tool to communicate with remote surgeons intraoperatively (5/31, 16%) [15,27,28,31,36]. Twenty-one studies (21/31, 68%) used Google Glass as a videography and photography device to document surgeries, laboratory images, or patient electronic medical records (7/21, 33%) [21,26,29,30,32,34,38], to assist in telementoring (4/21, 19%) [14,16-18], to document patient consultations (2/21, 10%) [19,33], to broadcast live streams (2/21, 10%) [31,37], and to enhance surgical education (7/21, 33%) [12,15,17,19-21,23]. One study used Google Glass as a hands-free search engine in the operating room (1/31, 3%) [27].

In preoperative settings (4/31, 13%), Google Glass was used in cardiac surgery (1/4, 25%) [32], neurosurgery (1/4, 25%) [19], pediatric surgery (1/4, 25%) [27], and emergency medicine (1/4, 25%) [33]. In these studies, Google Glass was tested primarily for its use in laboratory imaging interpretation and documentation (2/4, 50%) [32,33], surgical consultations (2/4, 50%) [19,33], teleconferencing (1/4, 25%) [27], and surgical education (1/4, 25%) [19].

In operative settings (27/31, 87%), Google Glass was used in various surgical specialties, including urology (3/27, 11%) [12,35,38], orthopedics (3/27, 11%) [13-15], general surgery (4/27, 15%) [16-18,39], cardiac surgery (1/27, 3.7%) [40], neurosurgery (3/27, 11%) [19,20,36], minimally invasive surgical procedures (6/27, 22%) [21-25,37], oncologic surgery (2/27, 7%) [26,41], pediatric surgery (1/27, 4%) [42], pediatric anesthesiology (1/27, 4%) [42], otolaryngology (1/27, 4%) [28], ophthalmology (1/27, 4%) [29], plastic surgery (1/27, 4%) [30], and solid organ transplant surgery (1/27, 4%) [31]. In these studies, Google Glass was utilized as a surgical education instrument (7/27, 26%) [12,15,17,19-21,23], portable surgical imaging display (5/27, 19%) [13,24,36,39,41], live stream transmitter (2/27, 7%) [31,37], vital sign monitor (6/27, 22%) [22,25,35,40-42], communication device (5/27, 19%) [15,27,28,31,36], telementoring tool (4/27, 15%) [14,16-18], audiovisual recording device to document surgeries and patient medical records (5/27, 19%) [21,26,29,30,38], and hands-free search engine (1/27, 4%) [27].

In postoperative settings (5/31, 16%), Google Glass was used in orthopedics (1/5, 20%) [15], neurosurgery (1/5, 20%) [19], pediatric surgery (1/5, 20%) [27], plastic surgery (1/5, 20%) [30], and wound care (1/5, 20%) [34]. These studies examined the utility of using Google Glass in recovery monitoring (2/5, 40%) [15,19], telemonitoring (1/5, 20%) [15], wound management (1/5, 20%) [34], video and photo review (2/5, 40%) [19,30], and administrative billing aid (1/5, 20%) [27].

Most studies (20/31, 65%) conducted formal follow-up surveys with study participants to determine the feasibility and usability of Google Glass [12,16-20,22,24-27,30,32,33,35,38-40,42]. Of the 31 studies, 28 (91%) studies assessed feasibility, usability, and/or acceptability by physicians only [12-25,28-32,34-42], two by both physicians and patients (6%) [27,33], and one by patients only (3%) [26]. The two studies (7%) that reported patients’ perceptions of using Google Glass cited a generally positive response toward its use [27,33], although one group of patients reported anxiety related to being recorded without their informed consent [27]. Additional user satisfaction, feasibility and technical results can be found in Multimedia Appendix 3.

In 19 of the studies, medical professionals were satisfied with the use of Google Glass (19/31, 61%) [12,14,17,18,20,22-25,27,30,32-38,42]. Five studies did not provide quantitative ratings on Google Glass, but concluded that it was easy to use or used successfully to livestream surgery, record procedures for later use in surgical education, or communicate with colleagues remotely (5/31, 16%) [15,19,28,29,31]. One study found the peripheral display of Google Glass superior to traditional monitors but inferior to another wearable “through-the-lens” display (1/31, 3%) [39]. One study did not find a significant difference in ease of use of reading ECG rhythms on a traditional computer screen versus Google Glass (1/31, 3%) [40]. One study found that 82% of its participants viewed Glass as inferior to traditional methods, such as videography using an Apple iPhone 5 (1/31, 3%) [16]. Three studies did not provide participant-reported ratings on acceptability (3/31, 10%) [13,21,41]. In the one study evaluating solely patients’ acceptability of the device, all patients were receptive to Google Glass (1/31, 3%) [26].

Those who viewed Google Glass favorably cited its usefulness (4/19, 21%) [18,20,22,38], educational helpfulness (4/19, 21%) [12,17,35,38], ease of use (7/19, 37%) [12,14,19,22,27,38,42], comfort (4/19, 21%) [12,24,35,42], low distractibility (4/19, 21%) [17,19,22,42], ability to aid attentiveness (3/19, 16%) [22,25,35], and image quality (1/19, 5%) [27], and acknowledged their consideration for using Google Glass in the future (4/19, 21%) [12,22,35,42]. One study also found that Google Glass allowed for greater situational awareness: during a follow-up interview, one physician remotely observed a vital sign deterioration in a patient that was thought to be stable (1/31, 3%) [25].

Despite the overall promising data regarding the feasibility and the acceptability of using Google Glass in different surgical settings, several studies (17/31, 55%) have reported a number of possible limitations associated with the use of Google Glass in these settings [13,16,19,20,24,25,27-30,33-35,37,38,40,42]. One study reported that although Google Glass was a beneficial remote communication device, it was unable to capture all relevant anatomy during a certain surgery (1/31, 3%) [28]. Other sources of apprehension arose due to short battery life (8/31, 26%) [13,19,20,25,27,29,35,38]; difficulty in hands-free features, such as the head-tilt zooms and the wink feature (5/31, 16%) [19,27,30,34,42]; data privacy concerns (4/31, 13%) [25,27,33,37]; lighting issues (4/31, 13%) [19,27-29]; Web connectivity issues (2/31, 6%) [19,27]; small screen size (2/31, 6.4%) [20,40]; image quality (1/31, 3%) [16]; distractibility (1/31, 3%) [30]; time lag (2/31, 6%) [19,24]; bulkiness (1/31. 3%) [28]; volume limitations (1/31, 3%) [27]; and overheating (1/31, 3%) [25]. These limitations indicate that further modification of Google Glass Explorer’s technical hardware is necessary before the spectacles can be integrated into the surgical field.

As today’s technology-centered society continues to place a growing emphasis on multitasking and unfettered access to information, Google Glass and other wearable devices have attracted the attention of consumers and corporations alike. Although Google Glass Explorer Edition failed to cater to the needs of the general public, the promising, multifunctional applications of this hands-free wearable device were appealing to several stakeholders in the health care industry, including surgeons. In this systematic review, we analyzed existing clinical studies on Google Glass to assess the feasibility, acceptability, benefits, and limitations of Google Glass in surgical settings.

Considering both the proposed strengths and limitations of using Google Glass, our review of these studies suggests that Google Glass Explorer could make the greatest potential impact in settings where it has less of an impact on patient safety, such as in aiding the surgical education of medical trainees. In its Explorer form, Google Glass is still restricted by a number of technological limitations, such as inadequate battery life and display overexposure, that might make it a beneficial supplement to traditional patient monitors but less so as an independent external monitor. Similarly, Web connectivity and poor Internet connection in isolated areas of the world still pose issues for Google Glass as a long-distance telementoring tool in situations when real-time surgical decisions are needed. Based on the studies, the environment in which Google Glass seems to provide the greatest benefit at the lowest risk to the patient is surgical education. Short-distance livestreaming of surgeries by physicians to trainees provides a unique first-person vantage point of surgeries, and Google Glass’s ability to provide augmented reality guidance in simulated surgeries has the potential to aid medical students in skill acquisition and task comprehension. For example, Evans et al [21] reported a greater checklist score, denoting a higher number of procedural steps visualized by clinicians, when using the first-person perspective Google Glass compared to a third-person external monitor. Brewer et al [17] also found that, when Google Glass was used to visualize a simulated operative field between learner and trainee, the time-to-task completion of a needle placement procedure was significantly lower.

Previous related research assessed the use of both Google Glass and similar heads-up technologies in the contexts of teleconsultation, physical therapy, pain management, telementoring, videography and photography, drug delivery, and image interpretation. However, whereas recent reviews of these studies examined the use of Google Glass in addition to other wearable devices in both general medicine and surgery [43], our systematic review exclusively considers Google Glass in surgical settings alone and draws only from research conducted clinically. Although there has been one systematic review conducted on Google Glass in surgical settings in the past, our review evaluated a greater sample size of studies (N=31) to account for the growing data on the topic; the most recent review on Google Glass in surgery included 17 studies in their analysis and relied on other systematic review articles in addition to original clinical studies in their research [44]. Therefore, our systematic review contributes to the growing evidence for the utilization of Google Glass in surgical settings. Nonetheless, the authors similarly concluded that Google Glass has the potential to positively serve the health care industry, especially in patient care and medical training.

As further research on the use of the original Google Glass in professional settings has arisen, it seems that Google Glass developers have also shifted their focus of Google Glass from the consumer market to industry settings, such as health care. Despite the cessation of Google Glass Explorer Edition production in 2015, Google Glass developer, X, announced in late July of 2017 the arrival of the Google Glass Enterprise Edition [45]. This version, intended to exclusively target businesses and commercial industries, has been quietly undergoing testing with a select group of clients. Of the 33 listed, eight (25%) are health systems (CHI Health, Dignity Health, Christiana Care Health System, Eastern Maine Medical Center, Sutter Health, Trinity Health, TriHealth, Klosterfrau Healthcare Group), and some have already attested to the benefits of this updated Glass to the medical field [46]. The majority of these corporations have been utilizing Google Glass in streamlining documentation in the consultation room. Using Google Glass as a “remote scribe,” doctors at Dignity Health reported a decrease in time spent recording notes from 33% of the day to less than 10%, allowing physicians to double the time they can spend on patient interaction [47].

Although it is uncertain whether the physicians have tested Google Glass Enterprise in a specifically surgical setting, this updated technology has already addressed many of the previously cited limitations and privacy concerns of the previous Glass Explorer. These include an upgrade in camera resolution from 5 megapixels to 8 megapixels, longer battery life, faster processor, a light that signals when video recording is taking place, and faster and more secure wireless connectivity [48]. Based on our review, most of the original research conducted on Glass Explorer that viewed Google Glass as a useful tool, based on promising data, cited these as primary sources of apprehension. Health care providers may be more willing to utilize Google Glass in the workplace if the new edition of Google Glass is able to overcome these known limitations. Thus, further research will determine whether Google Glass Enterprise will be more proficient than its predecessor in surgical settings.

Our findings were also corroborated by a recently published systematic review that assessed the feasibility of Google Glass in nonsurgical settings. In their analysis, Dougherty and Badawy [49] highlighted the responses toward the technical features of Google Glass in studies spanning a broad range of medical specialties as well as patient health concerns, from weight management to developmental disorders. The authors reported that participants, in some studies, were frustrated with Google Glass’s inadequate battery life, poor camera quality, hands-free shortcut functions, and potential to infringe on patient privacy. However, although the acceptability of Google Glass was more varied across the studies they included, our review elucidated more globally positive responses to the device in surgical settings. Nonetheless, the authors similarly found that Google Glass was most well received when leveraged as a tool for enhancing medical training. In support of our findings with the value of Google Glass in training and medical education in surgical settings, of the nine studies Dougherty and Badawy reviewed regarding student training, they reported that eight studies recommended the use of Google Glass for training purposes [10,24,42,50-54].

A number of strengths in our systematic review should be mentioned. First, we completed our review following established guidelines and recommendations for established systematic reviews methodology [55-57]. Second, two authors independently completed all stages of the review process. Finally, our search strategy for different databases was developed in collaboration with a librarian information specialist with more than 10 years of experience in systematic review methodology. In addition, no language restrictions were applied to minimize possible publication bias by including most relevant studies.

Potential methodological limitations in our systematic review should be discussed. First, some studies in our review included a relatively small sample size. Second, our inclusion criteria were limited to original research articles published in peer-reviewed journals, which could have led to a possible publication bias in which only positive study results are being reported and published [58]. Finally, although our literature search of five databases was comprehensive, it is possible that we could have missed a few articles related to our research question, which is also seen in other published systematic reviews [59].

In conclusion, there are promising feasibility and usability data of using Google Glass in surgical settings with particular benefits for surgical education and training. Despite existing technical limitations, Google Glass was generally well received and several studies acknowledged its potential for aiding the surgical field. As Glass Explorer’s successor, Glass Enterprise, becomes more integrated in the health care industry, further research will be necessary to evaluate the efficacy of this updated technology in supporting surgeons and their patients, especially with the growing evidence to support the efficacy of technology-based interventions, although cost-effectiveness is worth further study [60-62]. In doing so, clinicians may be able to better understand the environments in which wearable devices, such as Google Glass, can be most successful and how to offer their patients the most advanced comprehensive care.