From the desktop to the laptop to the mobile device, personal computing platforms evolve over time. Moving forward, wearable computing is widely expected to be integral to consumer electronics and beyond. The primary interface between a wearable computer and a user is often a near-eye display. However, current generation near-eye displays suffer from multiple limitations: they are unable to provide fully natural visual cues and comfortable viewing experiences for all users. At their core, many of the issues with near-eye displays are caused by limitations in conventional optics. Current displays cannot reproduce the changes in focus that accompany natural vision, and they cannot support users with uncorrected refractive errors. With two prototype neareye displays, we show how these issues can be overcome using display modes that adapt to the user via computational optics. By using focus-tunable lenses, mechanically actuated displays, and mobile gaze-tracking technology, these displays can be tailored to correct common refractive errors and provide natural focus cues by dynamically updating the system based on where a user looks in a virtual scene. Indeed, the opportunities afforded by recent advances in computational optics open up the possibility of creating a computing platform in which some users may experience better quality vision in the virtual world than in the real one.virtual reality | augmented reality | 3D vision | vision correction | computational optics E merging virtual reality (VR) and augmented reality (AR) systems have applications that span entertainment, education, communication, training, behavioral therapy, and basic vision research. In these systems, a user primarily interacts with the virtual environment through a near-eye display. Since the invention of the stereoscope almost 180 years ago (1), significant developments have been made in display electronics and computer graphics (2), but the optical design of stereoscopic near-eye displays remains almost unchanged from the Victorian age. In front of each eye, a small physical display is placed behind a magnifying lens, creating a virtual image at some fixed distance from the viewer (Fig. 1A). Small differences in the images displayed to the two eyes can create a vivid perception of depth, called stereopsis.However, this simple optical design lacks a critical aspect of 3D vision in the natural environment: changes in stereoscopic depth are also associated with changes in focus. When viewing a near-eye display, users' eyes change their vergence angle to fixate objects at a range of stereoscopic depths, but to focus on the virtual image, the crystalline lenses of the eyes must accommodate to a single fixed distance ( Fig. 2A). For users with normal vision, this asymmetry creates an unnatural condition known as the vergence-accommodation conflict (3, 4). Symptoms associated with this conflict include double vision (diplopia), compromised visual clarity, visual discomfort, and fatigue (3, 5). Moreover, a lack of accurate focus also removes a cu...
ABSTRACT. Objectives. To evaluate the work life and job satisfaction of pediatric generalists and subspecialists in comparison to each other and to a group of general internists and internal medicine subspecialists.Methods. Data were collected by survey of a national sample of 5704 general pediatricians, subspecialty pediatricians, general internists, internal medicine subspecialists, and family physicians who were selected randomly from the American Medical Association Masterfile using stratified sampling with disproportionate weighting to ensure ethnic diversity and representation of high managed care areas. Surveys were mailed up to 4 times and contained 150 items that reflected 10 facets of physician job satisfaction as well as an assessment of individual and practice demographic information. This study reports data from all groups except for family medicine.Results. The adjusted response rate was 58% for general pediatricians (n ؍ 590), 67% for specialty pediatricians (n ؍ 345), and 52% (n ؍ 1823) for the entire pool. In comparison with general internists, general pediatricians were more likely to be female (44% vs 24%); to work part time (20% vs 12%); to have lower annual income ($125 679 vs $143 875); and to report significantly higher levels of job, career, and specialty satisfaction on a 5-point scale (3.81 vs 3.52, 3.80 vs 3.55, and 3.76 vs 3.17 respectively). In comparison with internal medicine subspecialists, pediatric subspecialists were more likely to be female (42% vs 22%); to work in academically affiliated settings (35% vs 17%); to have lower incomes ($156 284 vs $192 006); to receive significantly less time for a complete history and physical examination (39 minutes vs 51 minutes); and to report similar levels of job, career, and specialty satisfaction (3.69 vs 3.71, 3.74 vs 3.78, and 3.60 vs 3.47 respectively). Of all 4 physician groups, general pediatricians worked the fewest hours (50/week), spent the greatest percentage of time in the office and the lowest percentage in the hospital (58% and 16%, respectively), saw the lowest percentage of patients with complex medical and complex psychosocial problems (15% and 17%, respectively), and were the least likely to endorse symptoms of burnout or job stress (13% and 18%, respectively). In comparison, pediatric subspecialists worked longer hours (59/week), spent the lowest percentage of time in the office and the greatest percentage of time in the hospital (22% and 44%, respectively), saw a much higher percentage of patients with complex medical and complex psychosocial problems (46% and 25%, respectively), and reported significantly higher levels of burnout and job stress (23% and 26%, respectively).Conclusions. Despite lower incomes, general pediatricians reported the highest levels of satisfaction and the least job stress of all 4 physician groups, whereas pediatric subspecialists reported levels of stress and burnout that raise significant concerns for the workforce of pediatric subspecialists of the future. Initiatives that improve clin...
Fig. 1. Conventional near-eye displays present a user with images that are perceived to be in focus at only one distance (top left, 1 m). If the eye accommodates to a different distance, the image is blurred (top left, 0.3 m and ∞). A point spread function (PSF) illustrates the blur introduced for a single point of light at each distance (insets). The fact that conventional near-eye displays have a single sharp focus distance can be problematic, because it produces focus cues that are inconsistent with a natural 3D environment. We propose a computational display system that uses PSF engineering to create a visual stimulus that does not change with the eye's accommodation distance (bottom left). This accommodation-invariant display mode tailors depth-invariant PSFs to near-eye display applications, allowing the eye to accommodate to arbitrary distances without changes in image sharpness. To assess the proposed display mode, we build a benchtop prototype near-eye display that allows for stereoscopic image presentation (right). An autorefractor is integrated into the prototype to validate the accommodation-invariant display principle with human subjects. Although emerging virtual and augmented reality (VR/AR) systems can produce highly immersive experiences, they can also cause visual discomfort, eyestrain, and nausea. One of the sources of these symptoms is a mismatch between vergence and focus cues. In current VR/AR near-eye displays, a stereoscopic image pair drives the vergence state of the human visual system to arbitrary distances, but the accommodation, or focus, state of the eyes is optically driven towards a fixed distance. In this work, we introduce a new display technology, dubbed accommodation-invariant (AI) near-eye displays, to improve the consistency of depth cues in near-eye displays. Rather than producing correct focus cues, AI displays are optically engineered to produce visual stimuli that are invariant to the accommodation state of the eye. The accommodation system can then be driven by stereoscopic cues, and the mismatch between vergence and accommodation state of the eyes is significantly reduced. We validate the principle of operation of AI displays using a prototype display that allows for the accommodation state of users to
As humans age, they gradually lose the ability to accommodate, or refocus, to near distances because of the stiffening of the crystalline lens. This condition, known as presbyopia, affects nearly 20% of people worldwide. We design and build a new presbyopia correction, autofocals, to externally mimic the natural accommodation response, combining eye tracker and depth sensor data to automatically drive focus-tunable lenses. We evaluated 19 users on visual acuity, contrast sensitivity, and a refocusing task. Autofocals exhibit better visual acuity when compared to monovision and progressive lenses while maintaining similar contrast sensitivity. On the refocusing task, autofocals are faster and, compared to progressives, also significantly more accurate. In a separate study, a majority of 23 of 37 users ranked autofocals as the best correction in terms of ease of refocusing. Our work demonstrates the superiority of autofocals over current forms of presbyopia correction and could affect the lives of millions.
Virtual reality systems are a popular tool in behavioral sciences. The participants’ behavior is, however, a response to cognitively processed stimuli. Consequently, researchers must ensure that virtually perceived stimuli resemble those present in the real world to ensure the ecological validity of collected findings. Our article provides a literature review relating to distance perception in virtual reality. Furthermore, we present a new study that compares verbal distance estimates within real and virtual environments. The virtual space—a replica of a real outdoor area—was displayed using a state-of-the-art head-mounted display. Investigated distances ranged from 8 to 13 m. Overall, the results show no significant difference between egocentric distance estimates in real and virtual environments. However, a more in-depth analysis suggests that the order in which participants were exposed to the two environments may affect the outcome. Furthermore, the study suggests that a rising experience of immersion leads to an alignment of the estimated virtual distances with the real ones. The results also show that the discrepancy between estimates of real and virtual distances increases with the incongruity between virtual and actual eye heights, demonstrating the importance of an accurately set virtual eye height.
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