Influence of virtual reality on visual parameters: immersive versus non-immersive mode

Pilot Study Assessing the Safety and Acceptance of a Novel Virtual Reality System to Improve Visual Function

PURPOSE

To assess the feasibility of the clinical use of a novel Virtual Reality (VR) training software designed to be used for active vision therapy in amblyopic patients by determining its preliminary safety and acceptance on the visual function of healthy adults.

METHODS

Pilot study enrolling 10 individuals (3 men, 7 women, mean age: 31.8 ± 6.5 years) with a best-corrected visual acuity (BCVA) of ≥ .90 (decimal) in both eyes were evaluated before and after 20 minutes of exposure to the NEIVATECH VR system using the HTC Vive Pro Eye head mounted display. Visual function assessment included near (40 cm) and distance (6 m) cover test (CT), stereopsis, binocular accommodative facility (BAF), near point of convergence (NPC), near point of accommodation (NPA), accommodative-convergence over accommodation (AC/A) ratio and positive and negative fusional vergences. Safety was assessed using the VR Sickness Questionnaire (VRSQ) and acceptance using the Technology Acceptance Model ;(TAM). Changes in all these variables after VR exposure were analyzed.

RESULTS

Short-term exposure to the NEIVATECH VR system only induced statistically significant changes in distance phoria (p = .016), but these changes were not clinically relevant. No significant changes were observed in VRSQ oculo-motricity and disorientation scores after exposure (p = .197 and .317, respectively). TAM scores showed a good acceptance of the system in terms of perceived enjoyment and perceived ease of use, although some concerns were raised in relation to the intention-to-use domain.

CONCLUSION

Exposure to the NEIVATECH VR system does not seem to adversely affect the visual function in healthy adults and its safety and acceptance profile seems to be adequate for supporting its potential use in other populations, such as amblyopic patients.

Impact of Immersive Virtual Reality on the Binocular and Accommodative Function: A Systematic Review About Literature and Its Current Limitations

The use of virtual reality (VR) is expected to increase exponentially in next years, and it is important to study whether VR can generate oculomotor, accommodative and binocular alterations in future users. Visual symptoms after the immersion inside VR have been widely reported, specifically in the case of simulator sickness, but the causes are still in study. Some authors have reported changes on accommodative and binocular parameters, but differences between studies made conclusions difficult.

PURPOSE

The aim of this study is to analyze the scientific literature about the effect of VR on the accommodative and binocular function of healthy subjects with both normal visual conditions and binocular anomalies assessing the quality of the existing studies to detect possible limitations and improve future study designs.

METHODS

A search was performed in PubMed, Web of Science and Scopus databases with the search equation (Virtual reality OR head-mounted displays) AND (accommodation OR accommodative) AND (vergence* OR convergence OR divergence OR binocular vision). A limitation was made in terms of the date of publication from 2010 onwards, identifying a total of 198 publications. Finally, 15 publications were included in the quality analysis. After a comprehensive analysis of the publications, a quality assessment was performed using a Quality Appraisal Checklist.

RESULTS

Research on effects of immersive VR on accommodative and binocular function to this date was focused on quasi-experimental pre-post studies well written and with results supporting their conclusions. Unfortunately, this scientific evidence provides heterogeneous outcomes, being the results in some cases even contradictory.

CONCLUSIONS

Information about the devices, its interpupillary distance adjustment, the software characteristics and type of task performed by users should be better controlled in future studies. Additionally, participants accommodative and binocular baseline characteristics should be better analyzed to obtain firm conclusions about the consequences of the proper immersive VR experience on visual function.

Study of the Possibility of Using Virtual Reality Application in Rehabilitation among Elderly Post-Stroke Patients

Thanks to medical advances, life expectancy is increasing. With it comes an increased incidence of diseases, of which age is a risk factor. Stroke is among these diseases, and is one of the causes of long-term disability. The opportunity to treat these patients is via rehabilitation. A promising new technology that can enhance rehabilitation is virtual reality (VR). However, this technology is not widely used by elderly patients, and, moreover, the elderly often do not use modern technology at all. It therefore becomes a legitimate question whether elderly people will be able to use virtual reality in rehabilitation. This article presents a rehabilitation application dedicated to patients with upper limb paresis and unilateral spatial neglect (USN). The application was tested on a group of 60 individuals including 30 post-stroke patients with an average age of 72.83 years. The results of the conducted study include a self-assessment by the patients, the physiotherapist's evaluation, as well as the patients' performance of the exercise in VR. The study showed that elderly post-stroke patients are able to use virtual reality applications, but the ability to correctly and fully perform an exercise in VR depends on several factors. One of them is the ability to make logical contact (p = 0.0001 < 0.05). However, the study presented here shows that the ability to use VR applications does not depend on age but on mental and physical condition, which gives hope that virtual reality applications can be used in post-stroke rehabilitation among patients of all ages.

Design guidelines for limiting and eliminating virtual reality-induced symptoms and effects at work: a comprehensive, factor-oriented review

Virtual reality (VR) can induce side effects known as virtual reality-induced symptoms and effects (VRISE). To address this concern, we identify a literature-based listing of these factors thought to influence VRISE with a focus on office work use. Using those, we recommend guidelines for VRISE amelioration intended for virtual environment creators and users. We identify five VRISE risks, focusing on short-term symptoms with their short-term effects. Three overall factor categories are considered: individual, hardware, and software. Over 90 factors may influence VRISE frequency and severity. We identify guidelines for each factor to help reduce VR side effects. To better reflect our confidence in those guidelines, we graded each with a level of evidence rating. Common factors occasionally influence different forms of VRISE. This can lead to confusion in the literature. General guidelines for using VR at work involve worker adaptation, such as limiting immersion times to between 20 and 30 min. These regimens involve taking regular breaks. Extra care is required for workers with special needs, neurodiversity, and gerontechnological concerns. In addition to following our guidelines, stakeholders should be aware that current head-mounted displays and virtual environments can continue to induce VRISE. While no single existing method fully alleviates VRISE, workers' health and safety must be monitored and safeguarded when VR is used at work.

An Immersive Virtual Kitchen Training System for People with Multiple Sclerosis: A Development and Validation Study

Rehabilitation via virtual reality (VR) training tools allows repetitive, intensive, and task-specific practice in a controlled and safe environment. Our goal was to develop and validate a novel immersive VR system based on the practice of real-life activities in a kitchen environment in people with multiple sclerosis (pwMS) with upper-limb dysfunction. The novel immersive VR kitchen application includes several tasks, i.e., tidying up the kitchen, preparing a hamburger and soup meal, and dish washing. Following the development phase, the system was tested for an 8-week intervention period on a small sample of pwMS suffering from upper-limb dysfunction. The Suitability Evaluation Questionnaire for VR systems served as the primary outcome. The scores for enjoyment, sense of comfort with the system, feelings of success and control, realism, easy-to-understand instructions, assists in rehabilitation therapy, were between 4.0 and 4.6, indicating a high satisfaction. The scores for eye discomfort, dizziness, nausea, and disorientation during practice were between 2.8 and 1.3, indicating a low-to-moderate interference of the system. The virtual kitchen training system is feasible and safe for upper-limb training in pwMS and paves the way for future RCTs to examine the benefits of the system compared with standard care, thus improving the functionality of the upper limbs in pwMS.

Effects of Virtual Reality on the Limb Motor Function, Balance, Gait, and Daily Function of Patients with Stroke: Systematic Review

Background and Objectives: This systematic review aimed to clarify the effectiveness of virtual reality rehabilitation on physical outcomes for people with stroke. Materials and Methods: Articles were searched through PubMed, EMBASE, the Cochrane Library, the Physiotherapy Evidence Database, CINAHL, Web of Science, and ProQuest Dissertations and Theses, from inception to 30 April 2022. Methodological quality was scored using the Assessing the Methodological Quality of Systematic Reviews 2 tool. Each systematic review for the outcome of interest was assessed by two independent reviewers using the Grading of Recommendations Assessment, Development, and Evaluation system. Results: Twenty-six articles were selected. These studies evaluated the effectiveness of virtual reality on limb motor function, balance, gait, and daily function in patients with stroke. The findings suggested a beneficial effect of virtual reality; there was a "very low" to "moderate" quality of evidence for improved limb extremity function, balance, and daily function, and a "very low" to "moderate" quality of evidence for improved gait. Conclusions: Despite widespread interest in the use of virtual reality rehabilitation, high-quality evidence for its routine use in stroke treatment is lacking. Further research is needed to determine the treatment modality, duration, and long-term effects of virtual reality on stroke populations.

Eye movement characteristics and visual fatigue assessment of virtual reality games with different interaction modes

This study aimed to investigate the eye movement characteristics and visual fatigue of virtual reality games with different interaction modes. Eye movement data were recorded using the built-in eye tracker of the VR device and eye movement parameters were calculated from the recorded raw data. The Visual Fatigue Scales and Simulator Sickness Questionnaire were used to subjectively assess visual fatigue and overall discomfort of the VR experience. Sixteen male and 17 female students were recruited for this study. Results showed that both the primary and 360 mode of VR could cause visual fatigue after 30 min of gameplay, with significant differences observed in eye movement behavior between the two modes. The primary mode was more likely to cause visual fatigue, as shown by objective measurements of blinking and pupil diameter. Fixation and saccade parameters also showed significant differences between the two modes, possibly due to the different interaction modes employed in the 360 mode. Further research is required to examine the effects of different content and interactive modes of VR on visual fatigue, as well as to develop more objective measures for assessing it.

Changes to Visual Parameters Following Virtual Reality Gameplay

Introduction:

Virtual reality (VR) gameplay is popular with a range of games and educational resources available. However, it puts high demands on the visual system. Current evidence shows conflicting impacts on visual parameters. Therefore, this study explores the changes to vision following VR gameplay.

Methods:

The study was conducted at the School of Health Sciences, University of Liverpool. All participants had binocular vision with good visual acuity and no manifest strabismus. Participants were assessed before and after playing 15 minutes of the VR game Beat Saber, which incorporated convergence and divergence movements. Clinical assessments including near point of convergence (NPC) and near point of accommodation (NPA) using the RAF rule; accommodative convergence to accommodation (AC/A) ratio; motor fusion using the prism fusion range (at 33cm), accommodation facility using +2.00/–2.00DS flipper lenses, and stereoacuity using the Frisby stereo test were assessed before and after playing.

Results:

Seventy-eight participants (19–25 years old) were included in the study, with 16 males and 41 females respectively. The breakpoint of convergence reduced by 0.5 cm (p = 0.001). The binocular accommodative facility improved by 2 cycles per minute (cpm); p = 0.004. The mean, near horizontal prism fusion range (PFR) base break and recovery points both worsened by of 5.0 dioptres (p = 0.003), whereas the mean near horizontal PFR base in recovery point improved by of 4.0 dioptres (p = 0.003).

Discussion:

The study validated previous findings as VR gameplay over-exercised and fatigued convergence muscles, but to a small degree. The VR experience improved the participants’ ability to change focus quickly and improve accommodation, as well as the divergence function of the eye. However, as the participants were retested directly after the VR gameplay, the findings were limited to short term effects on vision.

Non-Immersive Virtual Reality as an Intervention for Improving Hand Function and Functional Independence in Children With Unilateral Cerebral Palsy: A Feasibility Study

Introduction

Non-immersive virtual reality (NIVR) is emerging as an advantageous intervention in the arena of neurorehabilitation. Promising results have been obtained by the application of NIVR in adults with various chronic neurological conditions such as stroke and Parkinson’s disease, but studies on the use of NIVR in children with unilateral cerebral palsy (CP) are limited.

Materials and methods

This preliminary study included 10 school-aged participants with unilateral CP who were allocated into experimental and control groups. In accordance with the allocation ratio of 1:1, there were five participants in each group. During six weeks of intervention, children in the experimental group received NIVR intervention in addition to conventional physiotherapy, while those in the control group received only conventional physiotherapy, with a goal to improve hand function and functional independence. Nine-hole peg test (9HPT), box and block test (BBT), ABILHAND kids, and self-care section of functional independence measure for children (WeeFIM) were used as outcome measures.

Results

There was significant improvement in all outcome measures in both groups. However, the improvement in the hand function and functional independence was significantly more in the experimental group than in the control group.

Conclusion

It can be concluded that NIVR intervention in the management of children with unilateral CP seems to be feasible and useful. Further research with a larger sample size must be undertaken to reinforce these preliminary findings.

Variations in intraocular pressure and visual parameters before and after using mobile virtual reality glasses and their effects on the eyes

We examined the effects of using mobile devices with immersive virtual reality for a short period on the physiological parameters of both eyes. The average age of the 50 participants (23 men and 27 women) was 17.72 ± 1.48 years, and refractive error ranged from 0 D to − 5.00 D. All the participants wore + 3.00 D glasses and underwent a 5-min relaxation adjustment through the atomization method. The participants wore immersive virtual reality (VR) glasses to watch a movie on a roller coaster for 10 min. Their relevant physiological parameters of the eyes were measured both before and after using VR glasses. Compared with before VR use, no significant difference (P > 0.05) was observed in the near-horizontal vergence and refractive error but a significant difference (P < 0.05) was observed in the amplitude of accommodation, intraocular pressure, divergence/convergence, and stereopsis after VR use. The corneal elastic coefficient was > 0.2 MPa, and we used Friedenwald’s eye rigidity relationship to obtain the K value (0.065–0.09). Approximately 10% of the participants experienced cybersickness symptoms such as nausea and dizziness. The use of VR to watch three-dimensional movies reduced intraocular pressure, which may help prevent or treat glaucoma. Moreover, the binocular convergence was higher when viewing near-field objects in VR than in the real world. Therefore, individuals with convergence excess may experience symptoms. Binocular parallax is the most likely cause of cybersickness symptoms. Thus, mobile VR devices with higher quality and comfort are necessary.

When virtual and real worlds coexist: Visualization and visual system affect spatial performance in augmented reality

New visualization approaches are being actively developed aiming to mitigate the effect of vergence-accommodation conflict in stereoscopic augmented reality; however, high interindividual variability in spatial performance makes it difficult to predict user gain. To address this issue, we investigated the effects of consistent and inconsistent binocular and focus cues on perceptual matching in the stereoscopic environment of augmented reality using a head-mounted display that was driven in multifocal and single focal plane modes. Participants matched the distance of a real object with images projected at three viewing distances, concordant with the display focal planes when driven in the multifocal mode. As a result, consistency of depth cues facilitated faster perceptual judgments on spatial relations. Moreover, the individuals with mild binocular and accommodative disorders benefited from the visualization of information on the focal planes corresponding to image planes more than individuals with normal vision, which was reflected in performance accuracy. Because symptoms and complaints may be absent when the functionality of the sensorimotor system is reduced, the results indicate the need for a detailed assessment of visual functions in research on spatial performance. This study highlights that the development of a visualization system that reduces visual stress and improves user performance should be a priority for the successful implementation of augmented reality displays.

Effects of prolonged use of virtual reality smartphone-based head-mounted display on visual parameters: a randomised controlled trial

We investigated the effects of using a virtual reality smartphone-based head-mounted display (VR SHMD) device for 2 h on visual parameters. Fifty-eight healthy volunteers were recruited. The participants played games using VR SHMD or smartphones for 2 h on different days. Visual parameters including refraction, accommodation, convergence, stereopsis, and ocular alignment and measured choroidal thickness before and after the use of VR SHMD or smartphones were investigated. Subjective symptoms were assessed using questionnaires. We analyzed the differences in visual parameters before and after the use of VR SHMD or smartphones and correlations between baseline visual parameters and those after the use of the devices. Significant changes were observed in near-point convergence and accommodation, exophoric deviation, stereopsis, and accommodative lag after the use of VR SHMD but not after that of smartphones. The subjective discomfort associated with dry eye and neurologic symptoms were more severe in the VR group than in the smartphone group. There were no significant changes in refraction and choroidal thickness after the use of either of the two devices. The poorer the participants' accommodation and convergence ability the greater the resistance to changes in these visual parameters, and participants with a large exophoria were more prone to worsening of exophoria than those with a small exophoria.