A survey of visually induced symptoms and associated factors in spectators of three dimensional stereoscopic movies

Tolerance of immersive head-mounted virtual reality among older nursing home residents

Introduction

Virtual Reality (VR) is a tool that is increasingly used in the aging population. Head-Mounted Displays (HMDs) are stereoscopic vision devices used for immersive VR. Cybersickness is sometimes reported after head-mounted display (HMD) VR exposure. Cybersickness severity and anxiety state reflect VR low tolerance. We aimed to evaluate HMD VR tolerance among older nursing home residents through cybersickness and anxiety state.

Methods

A total of 36 participants were included in this preliminary study, 33 of whom (mean age: 89.33 ± 5.48) underwent three individual HMD VR sessions with three different contents. Cybersickness occurrence and severity were scored by the Simulator Sickness Questionnaire (SSQ) after each session. Anxiety state was assessed by the State-Trait Anxiety Inventory form Y-A before and after each session. Anxiety trait (using State-Trait Anxiety Inventory form Y-B) was also evaluated before and after the experiment. In total, 92% (33/36) of patients completed all three sessions, of which 61% (20/33) did not report any cybersickness symptoms (SSQ = 0). Six participants reported significant cybersickness (defined by an SSQ score ⩾10) in at least one session.

Discussion

Only two participants stopped the study after the first exposure because of cybersickness. Age, cognitive function, anxiety trait, and well-being were not associated with cybersickness. The mean anxiety state decreased significantly from pre- to post-session. This immersive HMD VR experience was well tolerated among nursing home dwellers. Further larger studies in this population aiming to identify CS determinants are needed in order to use HMD VR on a standard basis.

Cybersickness Variability by Race: Findings From 6 Studies and a Mini Meta-analysis

Background

With the influx of medical virtual reality (VR) technologies, cybersickness has transitioned from a nuisance experienced during leisure activities to a potential safety and efficacy concern for patients and clinicians. To improve health equity, it is important to understand any potential differences in cybersickness propensity among demographic groups, including racial groups.

Objective

This study aims to explore whether cybersickness propensity differs across racial groups.

Methods

We collected self-reported cybersickness ratings from 6 racially diverse independent samples within 1 laboratory group (N=931). In these studies, the participants were asked to perform tasks in VR such as traversing environments, pointing at and selecting objects, and interacting with virtual humans.

Results

Significant racial differences in cybersickness were found in 50% (3/6) of studies. A mini meta-analysis revealed that, on average, Black participants reported approximately one-third of SD less cybersickness than White participants (Cohen d=−0.31; P<.001), regardless of the nature of the VR experience. There was no overall difference in reported cybersickness between the Asian and White participants (Cohen d=−0.11; P=.51).

Conclusions

Racial differences in cybersickness indicate that researchers, practitioners, and regulators should consider patient demographics when evaluating VR health intervention outcomes. These findings lay the groundwork for future studies that may explore racial differences in cybersickness directly.

Image Size and the Range of Clear and Single Binocular Vision in 3D Displays

SIGNIFICANCE

The range of clear and single binocular vision differs between 3D displays and clinical prism vergences, but this difference is unexplained. This difference prevents clinicians from predicting the range of clear and single binocular vision in 3D-viewing patients. In this study, we tested a hypothesis for this difference.

PURPOSE

The purpose of this study was to determine whether changing fixation target size in 3D viewing significantly affects the vergence ranges and, if so, then to determine whether the target size effect is driven by fusional vergence gain changes, threshold of blur changes, or both.

METHODS

Twenty-one visually normal adults aged 18 to 28 years viewed 3D images at 40 cm in an electronic stereoscopic. The fixation target, a Maltese cross, moved in depth at 2∆/s by way of changing crossed or uncrossed disparity until blur and diplopia ensued. We used four target sizes: (1) small (width × height, 0.21° × 0.63°), (2) medium (1.43° × 4.3°), (3) large (3.6° × 10.8°), and (4) 3D (size changing congruently with disparity). The effect of target size on responses was tested by mixed ANOVAs.

RESULT

Mean convergence blurs and breaks increased with target size by 40% (P < .001) and 71% (P < .001), respectively, and in divergence by 33% (P = .03) and 30% (P = .04), respectively. The increases in break magnitude with target size implicate fusional vergence gain change in the size effect. Increasing target size raised the threshold of blur from 1.06 to 1.82 D in convergence and from 0.97 to 1.48 D in divergence (P = .008).

CONCLUSIONS

Growing fixation target size in 3D viewing increases fusional vergence gain and blur thresholds, which together increase the limits of clear and single binocular vision. Therefore, the clarity of a 3D image depends not only on its disparity but also on the size of the viewed image.

Free flap head and neck microsurgery with VITOMⓇ 3D: Surgical outcomes and surgeon's perspective

OBJECTIVE

To report on the application of the 3D exoscopic system to microsurgery in a cohort of head and neck cancer patients; to analyse the performance of microvascular anastomoses, flap harvesting and insetting under exoscopic view and to evaluate the surgeon's feedback after procedures.

METHODS

An observational study was performed on 10 consecutive patients undergoing exoscopic microsurgical free flap reconstruction. The VITOM^Ⓡ 3D system was applied to all procedures for microsurgical anastomoses, flap harvesting and insetting. Data about the type of resection and reconstruction, intraoperative and post-operative complications were recorded. Surgeon's feedback on exoscopic experience was collected through a questionnaire.

RESULTS

Reconstruction after oncologic demolition was performed by radial forearm flap in 3 cases (30%), antero-lateral thigh flap in 4 cases (40%), composite fibula flap in 2 cases (20%) and chimeric scapula flap in 1 case (10%). The mean surgical time for the microsurgical anastomoses (1 vein and 1 artery) was 34 min (range: 32-38). No intraoperative complications occurred and only two patients experienced pharyngo-cutaneous fistula in the post-operative time. There were neither cases of loss of flap, nor need of surgical revision. None of the cases had to be converted to OM technique. The surgeon never experienced back/neck pain, headache and nausea/vertigo. Occasionally, he felt tired and stressed and he reported eyestrain after one procedure only.

CONCLUSIONS

VITOM^Ⓡ 3D is easy to apply in the field of head and neck microsurgery and provides optimal stereoscopic view and anatomical details. Further studies are needed to validate indications and advantages of 3D exoscope as compared to OM.

Clear and Single Binocular Vision in Near 3D Displays

SIGNIFICANCE

Accommodation/convergence mismatch induced by 3D displays can cause discomfort symptoms such as those induced by accommodation/convergence mismatch in clinical vergence testing. We found that the limits of clear and single vision during vergence tests are very different between 3D and clinical tests. Clinical vergences should not be used as substitutes for measures of vergences in 3D displays.

PURPOSE

The purposes of this study were to determine whether the limits of clear and single binocular vision derived from phoropter prism vergence tests match the limits measured in a 3D display and to determine whether vergence mode, smooth versus jump, affected those limits in the 3D display.

METHODS

We tested the phoropter prism vergence limits of clear and single vision at 40 cm in 47 binocular young adults. In separate sessions, we tested, in a 3D display, the analogous 40-cm vergence limits for smooth vergence and jump vergence. The 3D fixation target was a Maltese cross whose visual angle changed congruently with target disparity.

RESULTS

Our mean phoropter vergence blur and break values were similar to those reported in previous studies. The mean smooth divergence limit was less in the 3D display (9.8Δ) than in the phoropter (12.8Δ). Most smooth convergence limits were much larger in the 3D display than in the phoropter, reaching the 35Δ limit of the 3D display without blur or diplopia in 24 subjects. Mean jump vergence limits were significantly smaller than smooth vergence limits in the 3D display.

CONCLUSIONS

The limits of clear and single binocular vision derived from phoropter vergence tests were not a good approximation of the analogous limits in our 3D display.

Stereoscopic 3D Optic Flow Distortions Caused by Mismatches between Image Acquisition and Display Parameters

We analyze the impact of common stereoscopic 3D (S3D) depth distortion on S3D optic flow in virtual reality (VR) environments. The depth distortion is introduced by mismatches between the image acquisition and display parameter. The results show that such S3D distortions induce large S3D optic flow distortions and may even induce partial/full optic flow reversal within a certain depth range, depending on the viewer's moving speed and the magnitude of S3D distortion introduced. We hypothesize that the S3D optic flow distortion may be a source of intra-sensory conflict that may be a source of visually induced motion sickness (VIMS) in S3D.

3D presentation in surgery: a review of technology and adverse effects

A systematic review was undertaken to assess the technology used to create stereovision for human perception. Adverse effects associated with artificial stereoscopic technology were reviewed with an emphasis on the impact of surgical performance in the operating room. MEDLINE/PubMed library databases were used to identify literature published up to Aug 2017. In the past 60 years, four major types of technologies have been used for reconstructing stereo images: anaglyph, polarization, active shutter, and autostereoscopy. As none of them can perfectly duplicate our natural stereoperception, user exposure to this artificial environment for a period of time can lead to a series of psychophysiological responses including nausea, dizziness, and others. The exact mechanism underlying these symptoms is not clear. Neurophysiologic evidences suggest that the visuo-vestibular pathway plays a vital role in coupling unnatural visual inputs to autonomic neural responses. When stereoscopic technology was used in surgical environments, controversial results were reported. Although recent advances in stereoscopy are promising, no definitive evidence has yet been presented to support that stereoscopes can enhance surgical performance in image-guided surgery. Stereoscopic technology has been rapidly introduced to healthcare. Adverse effects to human operators caused by immature technology seem inevitable. The impact on surgeons working with this visualization system needs to be explored and its safety and feasibility need to be addressed.

3D Cinema and Headache: The First Evidential Relation and Analysis of Involved Factors

Background

A possible link between 3D movies and headache (HA) has never been a target of specific and systematic investigations. The aim of this study was to investigate the relationship between 3D cinema and HA and to evaluate possible risk factors of developing HA during or after watching a 3D movie.

Methods

This was a prospective, non-randomized, observational study. Six thousand specifically designed questionnaires were distributed to consecutive cinema visitors. Relative HA risks for 2D- vs. 3D-movie visitors and the effects of background variables were analyzed.

Results

The questionnaire was filled and returned by 1293 persons. The mean age of responders was 33.0 ± 11.3 years. Individuals who viewed 3D movies reported HA during or after the movie 1.61 times more often than 2D-movie viewers (11.1% in 3D vs. 7.2% in 2D movies, p = 0.017). The risk was higher in women: 2.65 times for 2D (p = 0.019) and 1.85 times for 3D movies (p = 0.06), and decreased with age by 4.6% with each year for 2D (p = 0.0035) and by 3.2% for 3D movies (p = 0.0098). Among 3D-movie visitors, those with previous HAs were 4.17 times more prone to get a cinema-induced HA (p = 0.02). The risk was the highest for persons with migraine (OR = 3.37, p = 0.001).

Conclusion

For the first time, it was evidentially shown that 3D movies can provoke HA. Persons at risk are mostly younger women and/or migraineurs. Based on our results, for those belonging to the aforementioned risk groups, it can be mainly recommended to choose passive 3D technology and to view movies from the farthest possible distance.

Investigation of visually induced motion sickness in dynamic 3D contents based on subjective judgment, heart rate variability, and depth gaze behavior

Visually induced motion sickness (VIMS) is an important safety issue in stereoscopic 3D technology. Accompanying subjective judgment of VIMS with objective measurement is useful to identify not only biomedical effects of dynamic 3D contents, but also provoking scenes that induce VIMS, duration of VIMS, and user behavior during VIMS. Heart rate variability and depth gaze behavior are appropriate physiological indicators for such objective observation. However, there is no information about relationship between subjective judgment of VIMS, heart rate variability, and depth gaze behavior. In this paper, we present a novel investigation of VIMS based on simulator sickness questionnaire (SSQ), electrocardiography (ECG), and 3D gaze tracking. Statistical analysis on SSQ data shows that nausea and disorientation symptoms increase as amount of dynamic motions increases (nausea: p<;0.005; disorientation: p<;0.05). To reduce VIMS, SSQ and ECG data suggest that user should perform voluntary gaze fixation at one point when experiencing vertical motion (up or down) and horizontal motion (turn left and right) in dynamic 3D contents. Observation of 3D gaze tracking data reveals that users who experienced VIMS tended to have unstable depth gaze than ones who did not experience VIMS.

Balance and coordination after viewing stereoscopic 3D television

Manufacturers and the media have raised the possibility that viewing stereoscopic 3D television (S3D TV) may cause temporary disruption to balance and visuomotor coordination. We looked for evidence of such effects in a laboratory-based study. Four hundred and thirty-three people aged 4-82 years old carried out tests of balance and coordination before and after viewing an 80 min movie in either conventional 2D or stereoscopic 3D, while wearing two triaxial accelerometers. Accelerometry produced little evidence of any change in body motion associated with S3D TV. We found no evidence that viewing the movie in S3D causes a detectable impairment in balance or in visuomotor coordination.

High-definition resolution three-dimensional imaging systems in laparoscopic radical prostatectomy: randomized comparative study with high-definition resolution two-dimensional systems

BACKGROUND

Three-dimensional (3D) imaging systems have been introduced worldwide for surgical instrumentation. A difficulty of laparoscopic surgery involves converting two-dimensional (2D) images into 3D images and depth perception rearrangement. 3D imaging may remove the need for depth perception rearrangement and therefore have clinical benefits.

METHODS

We conducted a multicenter, open-label, randomized trial to compare the surgical outcome of 3D-high-definition (HD) resolution and 2D-HD imaging in laparoscopic radical prostatectomy (LRP), in order to determine whether an LRP under HD resolution 3D imaging is superior to that under HD resolution 2D imaging in perioperative outcome, feasibility, and fatigue. One-hundred twenty-two patients were randomly assigned to a 2D or 3D group. The primary outcome was time to perform vesicourethral anastomosis (VUA), which is technically demanding and may include a number of technical difficulties considered in laparoscopic surgeries.

RESULTS

VUA time was not significantly shorter in the 3D group (26.7 min, mean) compared with the 2D group (30.1 min, mean) (p = 0.11, Student's t test). However, experienced surgeons and 3D-HD imaging were independent predictors for shorter VUA times (p = 0.000, p = 0.014, multivariate logistic regression analysis). Total pneumoperitoneum time was not different. No conversion case from 3D to 2D or LRP to open RP was observed. Fatigue was evaluated by a simulation sickness questionnaire and critical flicker frequency. Results were not different between the two groups. Subjective feasibility and satisfaction scores were significantly higher in the 3D group.

CONCLUSIONS

Using a 3D imaging system in LRP may have only limited advantages in decreasing operation times over 2D imaging systems. However, the 3D system increased surgical feasibility and decreased surgeons' effort levels without inducing significant fatigue.

User experience while viewing stereoscopic 3D television

3D display technologies have been linked to visual discomfort and fatigue. In a lab-based study with a between-subjects design, 433 viewers aged from 4 to 82 years watched the same movie in either 2D or stereo 3D (S3D), and subjectively reported on a range of aspects of their viewing experience. Our results suggest that a minority of viewers, around 14%, experience adverse effects due to viewing S3D, mainly headache and eyestrain. A control experiment where participants viewed 2D content through 3D glasses suggests that around 8% may report adverse effects which are not due directly to viewing S3D, but instead are due to the glasses or to negative preconceptions about S3D (the 'nocebo effect'). Women were slightly more likely than men to report adverse effects with S3D. We could not detect any link between pre-existing eye conditions or low stereoacuity and the likelihood of experiencing adverse effects with S3D.

Microbiological safety of glasses dispensed at 3D movie theatres

Recent popularity of three-dimensional movies raised some concern about microbiological safety of glasses dispensed into movie theatres. In this study, we analysed the level of microbiological contamination on them before and after use and between theatres adopting manual and automatic sanitation systems. The manual sanitation system was more effective in reducing the total mesophilic count levels compared with the automatic system (P < 0.05), but no differences were found for coagulase-positive staphylococci levels (P = 0.22). No differences were found for mould and yeast between before and after levels (P = 0.21) and between sanitation systems (P = 0.44). We conclude that more evidences are needed to support microbiological risk evaluation.

Are there side effects to watching 3D movies? A prospective crossover observational study on visually induced motion sickness

Background

The increasing popularity of commercial movies showing three dimensional (3D) images has raised concern about possible adverse side effects on viewers.

Methods and Findings

A prospective carryover observational study was designed to assess the effect of exposure (3D vs. 2D movie views) on self reported symptoms of visually induced motion sickness. The standardized Simulator Sickness Questionnaire (SSQ) was self administered on a convenience sample of 497 healthy adult volunteers before and after the vision of 2D and 3D movies. Viewers reporting some sickness (SSQ total score>15) were 54.8% of the total sample after the 3D movie compared to 14.1% of total sample after the 2D movie. Symptom intensity was 8.8 times higher than baseline after exposure to 3D movie (compared to the increase of 2 times the baseline after the 2D movie). Multivariate modeling of visually induced motion sickness as response variables pointed out the significant effects of exposure to 3D movie, history of car sickness and headache, after adjusting for gender, age, self reported anxiety level, attention to the movie and show time.

Conclusions

Seeing 3D movies can increase rating of symptoms of nausea, oculomotor and disorientation, especially in women with susceptible visual-vestibular system. Confirmatory studies which include examination of clinical signs on viewers are needed to pursue a conclusive evidence on the 3D vision effects on spectators.