Effects of stereopsis on vection, presence and cybersickness in head-mounted display (HMD) virtual reality.

Stereopsis provides critical information for the spatial visual perception of object form and motion. We used virtual reality as a tool to understand the role of global stereopsis in the visual perception of self-motion and spatial presence using virtual environments experienced through head-mounted displays (HMDs). Participants viewed radially expanding optic flow simulating different speeds of self-motion in depth, which generated the illusion of self-motion in depth (i.e., linear vection). Displays were viewed with the head either stationary (passive radial flow) or laterally swaying to the beat of a metronome (active conditions). Multisensory conflict was imposed in active conditions by presenting displays that either: (i) compensated for head movement (active compensation condition), or (ii) presented pure radial flow with no compensation during head movement (active no compensation condition). In Experiment 1, impairing stereopsis by anisometropic suppression in healthy participants generated declines in reported vection strength, spatial presence and severity of cybersickness. In Experiment 2, vection and presence ratings were compared between participants with and without clinically-defined global stereopsis. Participants without global stereopsis generated impaired vection and presence similarly to those found in Experiment 1 by subjects with induced stereopsis impairment. We find that reducing global stereopsis can have benefits of reducing cybersickness, but has adverse effects on aspects of self-motion perception in HMD VR.

Vision Impairment Provides New Insight Into Self-Motion Perception.

Purpose: Leading causes of irreversible blindness such as age-related macular degeneration (AMD) and glaucoma can, respectively, lead to central or peripheral vision loss. The ability of sufferers to process visual motion information can be impacted even during early stages of eye disease. We used head-mounted display virtual reality as a tool to better understand how vision changes caused by eye diseases directly affect the processing of visual information critical for self-motion perception. Methods: Participants with intermediate AMD or early manifest glaucoma with near-normal visual acuities and visual fields were recruited for this study. We examined their experiences of self-motion in depth (linear vection), spatial presence, and cybersickness when viewing radially expanding patterns of optic flow simulating different speeds of self-motion in depth. Viewing was performed with the head stationary (passive condition) or while making lateral-sway head movements (active conditions). Results: Participants with AMD (i.e., central visual field loss) were found to have greater vection strength and spatial presence, compared to participants with normal visual fields. However, participants with glaucoma (i.e., peripheral visual field loss) were found to have lower vection strength and spatial presence, compared to participants with normal visual fields. Both AMD and glaucoma groups reported reduced severity in cybersickness compared to healthy normals. Conclusions: These findings strongly support the view that perceived self-motion is differentially influenced by peripheral versus central vision loss, and that patients with different visual field defects are oppositely biased when processing visual cues to self-motion perception.

Spatial presence depends on 'coupling' between body sway and visual motion presented on head-mounted displays (HMDs).

This study investigated the effects of simulating self-motion via a head-mounted display (HMD) on standing postural sway and spatial presence. Standing HMD users viewed simulated oscillatory self-motion in depth. On a particular trial, this naso-occipital visual oscillation had one of four different amplitudes (either 4, 8, 12 or 16 m peak-to-peak) and one of four different frequencies (either 0.125, 0.25, 0.5 or 1 Hz). We found that simulated high amplitude self-oscillation (approximately 16 m peak-to-peak) at either 0.25 Hz or 0.5 Hz: 1) generated the strongest effects on postural sway; and 2) made participants feel more spatially present in the virtual environment. Our findings provide insight into the parameters of simulated self-motion that generate the strongest postural responses within virtual environments. These postural constraints have valuable implications for improving our understanding of sensory processes underlying the ergonomic experience of virtual environments simulated using HMDs.

A holistic model of low vision care for improving vision-related quality of life.

Vision impairment can have a significant impact on the wellbeing and quality of life of an individual. Vision rehabilitation has the potential to improve these areas; however, four in five patients with vision impairment are not being referred to the appropriate services. Barriers to on-referral include, but are not limited to: (1) misunderstandings by both practitioners and patients alike regarding which individuals with vision impairment might benefit or qualify for low vision services; (2) lack of awareness of available services; (3) unfamiliarity with practice guidelines; (4) miscommunication between practitioners and patients; (5) required patient travel or limitations in access; and (6) the perceived costs of goods and services. Further, current referral patterns do not represent a holistic patient-centric approach. Vision-related quality of life questionnaires are tools which can assist health professionals in providing optimal individualised care. This review explores current evidence regarding low vision service delivery within Australia and globally, the impact of vision impairment on activities of daily living, the instruments used for the assessment of vision-related quality of life (VRQOL), competing priorities of individual needs in low vision services and rehabilitation, and provides recommendations for a more patient-centred model of care.