This study evaluated the dynamic visual acuity of candidates by implementing a King–Devick (K-D) test chart in a virtual reality head-mounted display (VR HMD) and an augmented reality head-mounted display (AR HMD). Hard-copy KD (HCKD), VR HMD KD (VHKD), and AR HMD KD (AHKD) tests were conducted in 30 male and female candidates in the age of 10S and 20S and subjective symptom surveys were conducted. In the subjective symptom surveys, all except one of the VHKD questionnaire items showed subjective symptoms of less than 1 point. In the comparison between HCKD and VHKD, HCKD was measured more rapidly than VHKD in all tests. In the comparison between HCKD and AHKD, HCKD was measured more rapidly than AHKD in Tests 1, 2, and 3. In the comparison between VHKD and AHKD, AHKD was measured more rapidly than VHKD in Tests 1, 2, and 3. In the correlation analyses of test platforms, all platforms were correlated with each other, except for the correlation between HCKD and VHKD in Tests 1 and 2. There was no significant difference in the frequency of errors among Tests 1, 2, and 3 across test platforms. VHKD and AHKD, which require the body to be moved to read the chart, required longer measurement time than HCKD. In the measurements of each platform, AHKD was measured closer to HCKD than VHKD, which may be because the AHKD environment is closer to the actual environment than the VHKD environment. The effectiveness of VHKD and AHKD proposed in this research was evaluated experimentally. The results suggest that treatment and training could be performed concurrently through the use of clinical test and content development of VHKD and AHKD.
To demonstrate that the near-point-of-convergence (npc) examination is performed subjectively, the visual fixation and four-prism diopter (Δ) base-out (BO) examinations can be conducted with a kiosk-type objective examination method based on gaze tracking, and can be compared with the existing method. Objective examination equipment was used to verify effectiveness. Fifteen adult men and women in their 20s and 30s (26.87 ± 3.31 years) with visual acuity of 0.8 (logMAR: 0.1, Snellen: 20/25(6/7.5)) or higher (corrected vision in the case of ametropia) underwent the npc, visual fixation, and 4 Δ BO examinations based on the existing examination method followed by the gaze-tracking-based kiosk-type examination method. Three examinations were performed, and a comparative analysis was conducted. The gaze tracking method used a method of extracting eye feature points, and it was judged that the ocular moved when the movement of 30 eye feature points at the edge of the iris was detected. In the comparison between the existing method and the kiosk-type method, there were no statistically significant differences in npc, visual fixation, and 4 Δ BO examinations. Npc examinations were performed extensively by the existing subjective method, however, it seems that these can be conducted objectively using the kiosk-type method. Visual fixation and 4 Δ BO examinations require high-examination proficiency because finely moving ocular movements need to be observed, but it is judged that examinations can be performed more easily and accurately when combined with the kiosk-type method. The symmetrical characteristics between the two test results are expected to serve as a basis for using the kiosk-type examination method in clinical practice.
Blink rate, a major physiological response in humans, directly affects ocular diseases such as keratitis and dry eye. The blink rate in normal eyes appears at a constant frequency of 6–30 times per minute and is constant for each individual. In a previous study, the blink rate decreased when viewing content with high intensity and realism. Therefore, we tried to investigate the change in blink rate when viewing the content in VR HMD (virtual reality head-mounted display) and AR (augmented reality) glasses environments. We compared and analyzed the blink rate in four environments: natural state, viewing monitor, viewing VR HMD, and viewing AR glasses. Twenty-one participants (age, 26.87 ± 3.31 years) viewed the content for 1 min in four environments. One-way repeated ANOVA was used to analyze the blink rate changes. The study showed that the blink rate was decreased in the monitor, VR HMD, and AR glasses environments compared to that in the natural environment. Comparing the VR HMD environment with the AR glasses environment showed that the blink rate decreased in the VR HMD environment. The results of this study can be used for content use safety recommendations (guidelines for safe use of contents due to decreased blink rate) in the VR HMD and AR glasses environments, which are currently attracting attention in the metaverse.
With the recent development of a digital rehabilitation system, research on the rehabilitation of amputees is accelerating. However, research on rehabilitation systems for patients with amputation of the lower extremities is insufficient. For the rehabilitation of amputees, it is important to maintain muscle mass through the improvement of muscle movement memory, continuous rehabilitation learning, and motivation to improve efficiency. The rehabilitation system in a virtual environment is convenient in that there is no restriction on time and space because rehabilitation training of amputees is possible without removing/attaching general prosthetic legs and robot prosthetic legs. In this paper, we propose an XR rehabilitation system for patients with lower extremity amputation to improve the motivational aspect of rehabilitation training. The proposed method is a system that allows patients and clinical experts to perform rehabilitation in the same environment using two XR equipment called HoloLens 2. The content was provided in the form of a game in which the number of movements of amputees was allocated as scores to enhance rehabilitation convenience and motivation aspects. The virtual 3D model prosthetic leg used in-game content worked through the acquisition and processing of the patient’s actual muscle EMG (ElectroMyoGraphy) signal. In order to improve reactivity, there was a time limit for completing the operation. The classified action should be completed by the amputee within the time limit, although the number of times set as the target. To complete the operation, the amputee must force the amputation area to exceed an arbitrarily set threshold. The evaluation results were evaluated through an independent sample T-test. we contribute to the development of digital rehabilitation simulation systems. XR rehabilitation training techniques, operated with EMG signals obtained from actual amputation sites, contribute to the promotion of rehabilitation content in patients with amputation of the lower extremities. It is expected that this paper will improve the convenience and rehabilitation of rehabilitation training in the future.
This paper presents the Zerotrope, an improved version of the classic phenakistiscope and zoetrope devices. This device is used to create a new 360-degree dynamic 3D display by the inclusion of a single ultra-realistic full-color hologram. The Zerotrope is built with a zero-degree transplane hologram mounted on a disk rotating at a constant speed. When a stroboscopic lamp synchronized with the rotation illuminates this hologram, the recorded characters, arranged radially around the center of the disk, are animated as in a stop-motion movie. The operation of the Zerotrope is successful and shows the effect of a 3D display without the need for special viewing aids.
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