Table 1.

A summary of the main findings of the systematic reviews about VR and AR.

Field	References	VR/AR	Main findings
Education	Uruthiralingam and Rea, (20)	VR/AR	Improved anatomical education for undergraduate and postgraduate students, residents, dentistry, and nursery students in 75 out of 87 reviewed papers.
	Zhao et al. (22) Kyaw et al. (19)	VR	Improved the test scores compared to other methods (e.g., lectures, textbooks, and dissections) in different anatomical fields (e.g., musculoskeletal, neurologic, and gastroenteric). Longer courses showed larger effect size than short ones. The more the learners could interact with the 3D virtual models, the more the gain in knowledge and in cognitive skills (e.g., history taking, counseling competencies, decision-making, and communication).
	Tang et al. (5)	AR	Improved test scores and higher satisfaction and learning engagement using MagicBook, an AR system that uses webcam or smartphone to recreate 3D interactive models.
	Quintero et al. (21)	AR	Increased the attention, interest and motivation of students, even with disabilities or special educational needs.
Oral and maxillofacial surgery	Joda et al. (4) Farronato et al. (58) Ayoub and Pulijala, (59)	VR/AR	Improved manual dexterity and surgical skills in undergraduate and postgraduate students. Improved the execution of several procedures, including caries and submandibular glands removal and orbital floor reconstruction. The simulations were able to detect students with potential learning challenges and to discriminate between novices and experts.
Surgery	Tang et al. (5) Barsom et al. (60) Wong et al. (61) Tang et al. (62) Meola et al. (63) Fida et al. (64)	VR/AR	Reduced intraoperative times, potential ischemic times, tissue damages in several medical procedures, including laparoscopic tasks, bone reconstruction, lumbar punctures, otorhinolaryngologic and neurosurgical operations. Facilitated and improved pancreatic, hepato-biliary, and urogenital surgery. Surgeons could manipulate the 3D virtual representation to assure to not expose or harm delicate tissues. The AR navigation system allowed to better view the anatomical structures, and reduced mental demand, physical demand, effort, and frustration compared to conventional navigation systems.
Psychology	Freeman et al. (2)	VRET, VR cognitive therapy	Improved specific phobias, social anxiety, PTSD, obsessive-compulsive disorder, generalized anxiety disorder, psychotic disorders (reduced distress and persecutory delusions, and improved social functioning), anorexia nervosa and cravings for substances. The effect sizes were comparable to face-to-face exposure therapy and quite large, and the results persisted for several years after the end of the therapy.
	Chicchi Giglioli et al. (65)	ARET	Improved phobia of small animals and acrophobia.
	Wechsler et al. (66)	VRET and VR cognitive therapy	Improved phobias (especially, specific phobia and agoraphobia) and anxiety more effective than inactive control groups (e.g., waitlist, placebo, or no treatment). Comparable to in vivo exposure or cognitive therapies. Slightly inferior for social phobia.
	Segawa et al. (67)	VRET	Mixed results for treating craving of several substances (i.e., nicotine, alcohol, cocaine, and cannabis) or behavior (i.e., gambling and internet gaming). Comparable to CBT in terms of effectiveness and relapse. A combination of VR, exposure, and cognitive therapy could be the best treatment course. Helped in eliciting cravings, thus allowing to comprehend which stimuli can trigger them.
	Fodor et al. (68)	VR and VRET	Reduced anxiety and depression more than control interventions (i.e., waitlist, placebo, relaxation), but similar to other psychological interventions.
	Eijlers et al. (69) Iannicelli et al. (70) Gujjar et al. (71) Chan et al. (72)	VR	Reduced anxiety and pain during medical procedures, including immunization, surgery, burn, dental, and oncological care, and venous access more than usual care (although the reviewed studies did not clearly describe usual care).
	Luo et al. (25)	VR	VR+analgesics for burn care (e.g., dressing change, and physical therapy) reduced unpleasantness, pain, the time spent thinking about pain, anxiety. VR was perceived as fun, even when the level of perceived presence was quite low (3.4 out of 10).
Physiotherapy and rehabilitation	de Amorim et al. (30)	VR	Improved static and dynamic balance, mobility, gait, and reduced sitting and standing time, fear and risk of falls in various elderly samples, healthy or with some disorder (e.g., balance deficit, diabetes mellitus, or PD) more than placebo, standard proprioceptive training, and kinesiotherapy
	Lee et al. (10) de Araújo et al. (18) Iruthayarajah et al. (26) Massetti et al. (28)	VR	Improved balance, stride length, sitting and standing time, when VR was used in rehabilitation programs for spinal cord injuries, limb and overall function in chronic stroke patients, PD, and multiple sclerosis. Improved aerobic and motor function, muscle tension, muscle strength, and activities of daily life alone or in combination with occupational therapy or physiotherapy. Some minor and transient adverse effects (e.g., musculoskeletal pain, fatigue, and dizziness) were reported.
	Ahern et al. (73)	VR	Reduced fear of movement in patients with LBP more than conventional stabilization exercises or physical therapy.
	Lei et al. (27)	VR	Improved HRQoL, level of confidence in difficult activities that could cause falls, and neuropsychiatric symptoms (i.e., anxiety and depression) more than standard care, conventional therapy, or any other non-VR rehabilitation program for PD.
	Manivannan et al. (74)	VR	Improved executive functions, driving attitude, attention, learning, and problem solving-skills in case of traumatic brain injury, but lack of improvement in employment rate.
	Pedroli et al. (75)	VR	Improved daily life in patients with USN. More useful than classical tests for assessing the severity of USN, since VR had the advantage of testing USN in simulated real-life conditions, e.g., driving in the streets.
Pain	Chi et al. (76)	VR	Reduced neuropathic pain in patients with spinal cord injuries through various VR systems (virtual walking, training, illusion, or hypnosis).
	Gumaa and Rehan Youssef, (77)	VR	Reduced chronic neck pain and shoulder impingement syndrome more than conventional therapy. VR was similar or inferior to exercises in many other conditions, including rheumatoid arthritis, knee arthritis, back pain, and fibromyalgia.
Pathophysiology	Bluett et al. (78)	VR	Improved understanding of the pathophysiology of freezing of gait in PD by reproducing this event in a safe environment (i.e., without the risk of a real fall).

AR, augmented reality; ARET, augmented reality exposure therapy; CBT, cognitive behavioral therapy; HRQoL, health-related quality of life; LBP, low back pain; PD, Parkinson's disease; PTSD, post-traumatic stress disorder; USN, unilateral spatial neglect; VR, virtual reality; VRET, virtual reality exposure therapy.