Collision avoidance in persons with homonymous visual field defects under virtual reality conditions

Standard automated perimetry (SAP) is the gold standard for evaluating the presence of visual field defects (VFDs). Nevertheless, it has requirements such as prolonged attention, stable fixation, and a need for a motor response that limit application in various patient groups. Therefore, a novel approach using eye movements (EMs) – as a complementary technique to SAP – was developed and tested in clinical settings by our group. However, the original method uses a screen-based eye-tracker which still requires participants to keep their chin and head stable. Virtual reality (VR) has shown much promise in ophthalmic diagnostics – especially in terms of freedom of head movement and precise control over experimental settings, besides being portable. In this study, we set out to see if patients can be screened for VFDs based on their EM in a VR-based framework and if they are comparable to the screen-based eyetracker. Moreover, we wanted to know if this framework can provide an effective and enjoyable user experience (UX) compared to our previous approach and the conventional SAP. Therefore, we first modified our method and implemented it on a VR head-mounted device with built-in eye tracking. Subsequently, 15 controls naïve to SAP, 15 patients with a neuro-ophthalmological disorder, and 15 glaucoma patients performed three tasks in a counterbalanced manner: (1) a visual tracking task on the VR headset while their EM was recorded, (2) the preceding tracking task but on a conventional screen-based eye tracker, and (3) SAP. We then quantified the spatio-temporal properties (STP) of the EM of each group using a cross-correlogram analysis. Finally, we evaluated the human–computer interaction (HCI) aspects of the participants in the three methods using a user-experience questionnaire. We find that: (1) the VR framework can distinguish the participants according to their oculomotor characteristics; (2) the STP of the VR framework are similar to those from the screen-based eye tracker; and (3) participants from all the groups found the VR-screening test to be the most attractive. Thus, we conclude that the EM-based approach implemented in VR can be a user-friendly and portable companion to complement existing perimetric techniques in ophthalmic clinics.

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Salzburg Visual Field Trainer (SVFT): A virtual reality device for (the evaluation of) neuropsychological rehabilitation

10.1101/2021.03.25.21254352 ◽

2021 ◽

Author(s):

Michael Christian Leitner ◽

Dirk Christoph Gütlin ◽

Stefan Hawelka

Keyword(s):

Virtual Reality ◽

Visual Field ◽

Predictive Value ◽

Visual Field Defects ◽

Neuropsychological Rehabilitation ◽

Hit Rate ◽

Neurological Patients ◽

The Individual ◽

Field Defects ◽

Blind Spots

AbstractObjectiveSo-called “Visual Restitution Therapies” (VRT) claim to ameliorate visual field defects of neurological patients by repeated visual light stimulation, leading to training-related neuroplasticity and resulting in reconnection of lesioned neurons in early cortical areas. Because existing systems are stationary, uncomfortable and unreliable, we developed a training instrument based on virtual reality goggles. The goal of the “Salzburg Visual Field Trainer” (SVFT) is twofold: (1) The device facilitates the clinical evaluation of established neuropsychological rehabilitation approaches, such as VRT. (2) The device enables patients to independently perform VRT based (or other) neuropsychological training methodologies flexibly, comfortably and reliably.Methods and AnalysisThe SVFT was developed on the principles of VRT. Individual configuration of the SVFT is based on perimetric data of the respective patient’s visual field. To validate the utmost important procedure in neuropsychological rehabilitation methodologies - that is displaying stimuli precisely in desired locations in the user’s visual field - two steps were conducted in this proof-of-concept study: First, we assessed the individual “blind spots” location and extent of 40 healthy, normal sighted participants. This was done with the help of our recently developed and validated perimetric methodology “Eye Tracking Based Visual Field Analysis” (EFA). Second, depending on the individual characteristics of every participant’s blind spots, we displayed - with the help of the SVFT - 15 stimuli in the respective locations of every participants’ blind spots and 85 stimuli in the surrounding, fully intact visual area. The ratio between visible and non-visible stimuli, which reflects in the documented behavioral response (clicks on a remote control) of the 40 participants, provides insight into the accuracy of the SVFT to display training stimuli in areas desired by the investigator. As the blind spot is a naturally occurring, absolute scotoma in human vision, we utilized this blind area as an objective criterion and a “simulated” visual field defect to evaluate the (technical) methodology of SVFT.ResultsOutcomes indicate that the SVFT and its methodology is highly accurate in displaying training stimuli in desired areas of the user’s visual field with an accuracy of 99.0%. Data analysis further shows a sensitivity of .980, specificity of .992, positive predictive value of .955, negative predictive value of .996, hit rate of .990, random hit rate of .742 and RATZ-Index of .976. This translates to 14.7% correct non-reactions, 0.7% false non-reactions, 0.3% false reactions and 84.3% correct reactions to displayed test stimuli during the evaluation study with the SVFT. Reports from participants further indicate that the SVFT is comfortable to wear and intuitive to use.ConclusionsThe SVFT can help to investigate the true effects of VRT based methodologies (or other neuropsychological approaches) and the underlying mechanisms of training-related neuroplasticity in early regions of the visual cortex in neurological patients suffering from visual field defects.

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Faculty Opinions recommendation of Gaze patterns predicting successful collision avoidance in patients with homonymous visual field defects.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.717953517.793459068 ◽

2012 ◽

Author(s):

Michael Crossland

Keyword(s):

Visual Field ◽

Collision Avoidance ◽

Visual Field Defects ◽

Gaze Patterns ◽

Field Defects

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Driving performance in patients with homonymous visual field defects and healthy subjects in a standardized virtual reality environment

Acta Ophthalmologica ◽

10.1111/j.1755-3768.2008.4421.x ◽

2008 ◽

Vol 86 ◽

pp. 0-0

Author(s):

E PAPAGEORGIOU ◽

G HARDIESS ◽

R VONTHEIN ◽

B SCHOENFISCH ◽

H MALLOT ◽

...

Keyword(s):

Virtual Reality ◽

Visual Field ◽

Healthy Subjects ◽

Driving Performance ◽

Visual Field Defects ◽

Virtual Reality Environment ◽

Field Defects

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Salzburg Visual Field Trainer (SVFT): A virtual reality device for (the evaluation of) neuropsychological rehabilitation

PLoS ONE ◽

10.1371/journal.pone.0249762 ◽

2021 ◽

Vol 16 (9) ◽

pp. e0249762

Author(s):

Michael Christian Leitner ◽

Dirk Christoph Guetlin ◽

Stefan Hawelka

Keyword(s):

Virtual Reality ◽

Visual Field ◽

Predictive Value ◽

Visual Field Defects ◽

Neuropsychological Rehabilitation ◽

Hit Rate ◽

Neurological Patients ◽

The Individual ◽

Field Defects ◽

Blind Spots

Objective “Visual Restitution Therapies” (VRT) claim to ameliorate visual field defects of neurological patients by repeated visual light stimulation, leading to training-related neuroplasticity and resulting in reconnection of lesioned neurons in early cortical areas. Because existing systems are stationary, uncomfortable, and unreliable, we developed a training instrument based on virtual reality goggles. The goal of the “Salzburg Visual Field Trainer” (SVFT) is twofold: (1) The device facilitates the clinical evaluation of established neuropsychological rehabilitation approaches, such as VRT. (2) The device enables patients to independently perform VRT based (or other) neuropsychological training methodologies flexibly and comfortably. Methods and analysis The SVFT was developed on the principles of VRT. Individual configuration of the SVFT is based on perimetric data of the respective patient’s visual field. To validate the utmost important aspect of neuropsychological rehabilitation methodologies—that is displaying stimuli precisely in desired locations in the user’s visual field—two steps were conducted in this proof-of-concept study: First, we assessed the individual “blind spots” location and extent of 40 healthy, normal sighted participants. This was done with the help of our recently developed perimetric methodology “Eye Tracking Based Visual Field Analysis” (EFA). Second, depending on the individual characteristics of every participant’s blind spots, we displayed—by means of the SVFT—15 stimuli in the respective locations of every participants’ blind spots and 85 stimuli in the surrounding, intact visual area. The ratio between visible and non-visible stimuli, which is reflected in the behavioral responses (clicks on a remote control) of the 40 participants, provides insight into the accuracy of the SVFT to display training stimuli in areas desired by the investigator. As the blind spot is a naturally occurring, absolute scotoma, we utilized this blind area as an objective criterion and a “simulated” visual field defect to evaluate the theoretical applicability of the SVFT. Results Outcomes indicate that the SVFT is highly accurate in displaying training stimuli in the desired areas of the user’s visual field with an accuracy of 99.0%. Data analysis further showed a sensitivity of .98, specificity of .99, a positive predictive value of .96, a negative predictive value of .996, a hit rate of .99, a random hit rate of .74 and a RATZ-Index of .98. This translates to 14.7% correct non-reactions, 0.7% false non-reactions, 0.3% false reactions and 84.3% correct reactions to displayed test stimuli during the evaluation study. Reports from participants further indicate that the SVFT is comfortable to wear and intuitive to use. Conclusions The SVFT can help to investigate the true effects of VRT based methodologies (or other neuropsychological approaches) and the underlying mechanisms of training-related neuroplasticity in the visual cortex in neurological patients suffering from visual field defects.

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