Vergence-Accommodation Conflict: Increased Presbyopia in Virtual Reality.

BACKGROUND: Performance and symptoms in completing a visual search task on a PC monitor and using a head-mounted display (HMD) were compared for different viewing conditions and between users of different ages. PATIENTS AND METHODS: Twenty-three young (M = 30 y, SD = 7 y) and 23 older (M = 52 y, SD = 5 y) participants performed a visual search task presented on a PC monitor. The task was repeated using an HMD for a near and a far virtual viewing distance. Reaction times (RT), detection sensitivity (d'), and symptoms were recorded for the three different viewing conditions. RESULTS: RT and d' were not affected by the viewing condition (p > 0.05). In contrast, symptoms significantly depended on the viewing condition but were, in part, not significantly affected by age. It is interesting to note that although not significant, young participants reported more ocular symptoms than older participants in the near vision task carried out using the HMD. DISCUSSION: HMD increases visual symptoms. However, HMD could be, in part, a remedy to problems when using visual aids for near work, in particular for presbyopes.

Head-mounted display versus computer monitor for visual attention screening: A comparative study.

Visual attention is crucial to many tasks during working. When it is impaired, the risk of occupational accidents is increased. A potential accident prevention would be the tracking of employees' attentional states to construct break regimes. There is a promising visual attention test administered on a computer monitor (CM) that has several advantages over widely used continuous performance tests in detecting inattentiveness in occupational environments. However, as the setup with a CM is impractical for the use in particular working environments (e.g., lack of space or disturbing exposure to light), the test was implemented into a head-mounted display (HMD). This study aimed to investigate whether the HMD version of the test is a suitable alternative to the CM version. For this purpose, participants (N = 30; 20-29 y) performed both tests. The performance on the HMD was significantly lower than on the CM. Moreover, the performances were compared with normative data recorded with a CM in a previous study. These data significantly differ from the data recorded with the CM in the present study. This emphasizes the importance of a standardized test environment, which could be provided by an HMD. Conclusively, this study revealed that the new VR tool, based on a previous test designed to assess visual skills in a complex visual environment, exhibited good psychometric property regarding the reliability. In additional, no problems were revealed regarding the functionality and usability of the HMD.

The Redesign of a Checklist for Evaluating Driver Impairment: A Human Factors and Ergonomics Approach.

The Cantonal Police of Zurich, Switzerland, use a checklist to identify impaired drivers when conducting traffic stops. This checklist was developed by subject-matter experts and has been in use for eight years. The goal of this study was to redesign the checklist while considering human factors and ergonomics principles in combination with findings from a retrospective analysis of a set of 593 completed checklists. The checklist was amended in accordance with the results of the retrospective analysis by adding missing items and discarding superfluous ones. In addition, a hierarchical cluster analysis of the retrospective data suggested an improved spatial organization of checklist elements and the grouping of similar items of the checklist. Furthermore, aspects related to Fitts's law, visual complexity, and an optimized direction of processing the checklist underpinned the design process. The results of an evaluation of the redesigned checklist by 11 laypeople and 13 police officers indicated an improved usability of the redesigned checklist over the original.

Towards the Validation of an Observational Tool to Detect Impaired Drivers-An Online Video Study.

Abuse of alcohol and other drugs is a major risk factor at work. To reduce this risk, workplace drug testing is performed in transportation and other industries. VERIFY, an observational method, is one of the key elements in a procedure adopted by the police of the canton of Zurich, Switzerland, for detecting impaired drivers. The observational method has been successfully applied by adequately trained police officers since 2014. The aim of this study is to examine the interrater reliability of the observational method, the effect of training in use of the method, and the role of having experience in the police force and traffic police force on the outcome when rating a driver's impairment. For this purpose, driver impairment in staged road traffic controls presented in videos was rated by laypeople (n = 81), and police officers without (n = 146) and with training (n = 172) in the VERIFY procedure. In general, the results recorded for police officers with training revealed a moderate to very good interrater reliability of the observational method. Among the three groups, impaired drivers were best identified by officers with training (ranging between 82.6% and 89.5% correct identification). Trained officers reported a higher impairment severity of the impaired drivers than the other two groups, indicating that training increases sensitivity to signs of impairment. Our findings also suggest that online video technology could be helpful in identifying impaired drivers. Trained police officers could be connected to a road traffic control to make observations via live video. By this method efficiency and reliability in detecting abuse of alcohol and other drugs could be improved. Our findings also apply to workplace drug testing in general.

Effects of viewing distance and age on the performance and symptoms in a visual search task in augmented reality.

In augmented reality (AR), virtual information is optically combined with the physical environment. In the most frequently used combination technique, optical settings in AR depart from the settings in natural viewing. Depending on the combination of viewing distances of the virtual task and its physical background, this deviation may lower visual performance and cause visual disturbance symptoms. The so-called vergence-accommodation conflict (VAC) has been identified as a cause for the visual disturbance symptoms in AR. In this study, for various distance combinations, the performance and symptoms when performing a search task displayed in a see-through head-mounted display (AR HMD, HoloLens 1st generation, Microsoft, USA) was investigated. The search task was displayed at a virtual distance of either 200 cm or 30 cm, and the real background was viewed either at a distance of 200 cm or 30 cm. Three combinations of viewing distances for the background and the virtual task were studied: 200 cm/200 cm, 200 cm/30 cm, and 30 cm/30 cm. Results revealed that both performance and visual disturbance symptoms depend on the combination of the viewing distances of the physical background and the virtual task. When the physical background was viewed at a distance of 200 cm, younger participants showed a significantly better search performance and reported stronger symptoms compared with older participants, no matter whether the virtual task was performed at 30 cm or at 200 cm. However, with the physical background at a distance of 30 cm, the performance of the younger group dropped to the level of the performance of the older group, and younger participants tended to report a stronger increase in visual disturbance symptoms compared with the older participants. From the AR HMD technology used in this study, it can be concluded that a near viewing distance of the virtual task does not cause a negative impact on performance and visual disturbance symptoms, provided any physical background seen through the AR HMD is not at a near viewing distance. The findings indicate that the VAC, which persists in augmented and virtual reality, depends, in addition to the physical component evaluating the optical distance, on a cognitive component evaluating the perceived distance. AR settings should therefore also be evaluated in terms of possible effects on perceived distance.

Development of Ophthalmic Microsurgery Training in Augmented Reality.

BACKGROUND: Using a group of 23 physician trainees, we investigated whether microsurgery training in an augmented reality (AR) training simulator improves motor skills and whether an intelligent tutoring system (ITS) improves training efficiency. METHODS: Characteristic motor skill steps involved in the peeling of an internal limiting membrane (ILM) were identified and implemented in the AR simulation. For training, implemented steps were either presented in the natural sequence, as in a real ILM surgery, or administered according to the ITS. Participants underwent the training over 5 days for 10 minutes per day. A subgroup of 11 participants performed the 5 microsurgical steps in a natural sequence. The other 12 participants used the ITS method. Motor skill performance was recorded before and after each training session with the AR simulator, and before the first and after the last training session using a method that did not rely on AR. RESULTS: Five steps of the ILM peeling procedure were identified and implemented: insertion of the instrument, flap creation, clockwise peeling, counterclockwise peeling, and retraction of the instrument. Both training methods significantly improved the motor skills of the participants. In both methods, steep learning progress was found within the first three training sessions. In both methods, motor skills continued to improve on days 4 and 5, but at a slower rate. After the 5 training days, performance was significantly improved, but improvement did not depend significantly on the training method. However, within the first 3 days of training, ITS led to steeper training progress than the natural sequence method. CONCLUSION: It is possible to improve microsurgical motor skills using the implemented AR simulation. Some technical limitations, such as system lag, deserve further improvements. However, the proposed AR solution was highly appreciated by the participants and could help overcome constraints of practice in microsurgical training, such as limited availability of training opportunities or a standardized assessment of motor skill performance.

Augmented Reality Microsurgery: A Tool for Training Micromanipulations in Ophthalmic Surgery Using Augmented Reality.

INTRODUCTION: Current methods of training microsurgical interventions have various limitations, including limited transferability to the human model, economic demands, and ethical concerns. In this article, we show how surgery simulations can overcome these issues and how, combined with the application of an intelligent tutoring system (ITS), they can be used to train tasks in ophthalmic surgery more efficiently. METHODS: We investigated physician trainee efficiency of learning microsurgical skills using our purpose-built microsurgery simulator that tracks a micromanipulator and displays a three-dimensional representation of the interior of a human eye in an augmented reality (AR) headset. The expertise of ophthalmic surgeons helped define five subtasks corresponding to the steps of internal limiting membrane peeling. Using our AR surgery simulation, 50 participants underwent two training sessions, one using the ITS that dynamically adapts the task sequence to the participant's progress and one using a fixed task sequence. RESULTS: We found significant improvement in micromanipulation performance in the first training session with both the ITS and classic training. In the second session, however, only the participants training with the ITS had further improvements in performance. CONCLUSIONS: Results of this study demonstrate the usability of AR simulation in training micromanipulation skills and support the claim that simulators can be used in ophthalmic surgery training. This study also extends the existing literature by demonstrating an application of ITS for surgical training. The potential of this method is further analyzed in ongoing studies and discussions with experts in ophthalmic surgery.

Training visual attention in a naturalistic visual environment.

The efficiency of training visual attention in the central and peripheral visual field was investigated by means of a visual detection task that was performed in a naturalistic visual environment including numerous, time-varying visual distractors. We investigated the minimum number of repetitions of the training required to obtain the top performance and whether intra-day training improved performance as efficiently as inter-day training. Additionally, our research aimed to find out whether exposure to a demanding task such as a microsurgical intervention may cancel out the effects of training. Results showed that performance in visual attention peaked within three (for tasks in the central visual field) to seven (for tasks in the periphery) days subsequent to training. Intra-day training had no significant effect on performance. When attention training was administered after exposure to stress, improvement of attentional performance was more pronounced than when training was completed before the exposure. Our findings support the implementation of training in situ at work for more efficient results. Practitioner Summary: Visual attention is important in an increasing number of workplaces, such as with surveillance, inspection, or driving. This study shows that it is possible to train visual attention efficiently within three to seven days. Because our study was executed in a naturalistic environment, training results are more likely to reflect the effects in the real workplace.

Consumers' food selection behaviors in three-dimensional (3D) virtual reality.

Virtual reality (VR) can be a useful tool for conducting consumer behavior experiments. The aim of this research was to examine whether people standing in front of a supermarket shelf make similar decisions and process similar information as those in front of a shelf in a VR shop. In Study 1, participants were asked to select a cereal from among 33 commercially available types of cereals placed on a shelf. One group performed the task in front of a real shelf, while the other performed it in VR. Eye-tracking data were collected for both groups. No statistically significant differences were observed in the selection of the cereals by the two groups in the two conditions. Eye-tracking data only revealed few differences in the information-seeking behavior. In Study 2, results observed using real products were replicated in VR. Participants were asked to walk through a virtual supermarket and select either a healthy cereal (healthy condition) or a tasty cereal (hedonic condition). Results showed that participants in the healthy condition paid more attention to the nutrition information than those in the hedonic condition. The results of these two experiments suggest that a VR condition wherein participants can walk around and behave as in the real world is a useful tool for conducting experiments related to food decisions.

Instrument for high-speed recording of accommodation of the human eye.

We developed an instrument used for recording the dynamics of accommodation of the eye. With this new technique, a recording speed of up to 95 Hz can be achieved. As components used in our system are mechanically fixed, artifacts owing to movable mechanical parts are excluded. Recording samples demonstrate the potential use of this instrument. This instrument also enables assessment of gaze direction simultaneously with accommodation.

A simple video-based system for examining irregularities in very slow, smooth-pursuit eye movements in cancer patients.

Subjective observations made during routine examination of eye movement functions (orthoptic status) reveal that very slow, smooth-pursuit eye movements in cancer patients are irregular. To objectively measure such movements, a video-based system was built to allow analysis of very slow, smooth-pursuit eye movements (1.8 degrees /s). Analysis involves quantification of drift and jerk-like gaze movements that cause deviations in gaze direction from the predicted trajectory. Gaze deviations observed in cancer patients are compared to those for the normal population. Our results show that deviations are more important in cancer patients than in the normal population. The difference is statistically significant (p<0.05) for deviations ranging between 0.75 degrees and 1.75 degrees . In the future, the system may possibly be used in the diagnosis of cancer.

Effect of subjective and objective workload on asthenopia at VDU workplaces.

An ergophthalmological tool has been developed to investigate effects of subjective and objective workload on work-related visual complaints (asthenopia). In field studies on different visual display unit (VDU) workplaces effects of objective and subjective workload, work intensity, and work breaks (5-9 min/hour) could be found. It could be shown that during the first hours of VDU work, asthenopic complaints have the tendency to follow effective workload. With increasing working time the effect of a general and visual fatigue overlaps other reported visual complaints in the majority of cases.