Showing papers by "Eli Peli published in 2017"

Multiplexing Prisms for Field Expansion.

Abstract: PURPOSE Prisms used for field expansion are limited by the optical scotoma at a prism apex (apical scotoma). For a patient with two functioning eyes, fitting prisms unilaterally allows the other eye to compensate for the apical scotoma. A monocular patient's field loss cannot be expanded with a conventional or Fresnel prism because of the apical scotoma. A newly invented optical device, the multiplexing prism (MxP), was developed to overcome the apical scotoma limitation in monocular field expansion. METHODS A Fresnel-prism-like device with alternating prism and flat elements superimposes shifted and see-through views, thus creating the (monocular) visual confusion required for field expansion and eliminating the apical scotoma. Several implementations are demonstrated and preliminarily evaluated for different monocular conditions with visual field loss. The field expansion of the MxP is compared with the effect of conventional prisms using calculated and measured perimetry. RESULTS Field expansion without apical scotomas is shown to be effective for monocular patients with hemianopia or constricted peripheral field. The MxPs are shown to increase the nasal field for a patient with only one eye and for patients with bitemporal hemianopia. The MxPs placed at the far temporal field are shown to expand the normal visual field. The ability to control the contrast ratio between the two images is verified. CONCLUSIONS A novel optical device is demonstrated to have the potential for field expansion technology in a variety of conditions. The devices may be inexpensive and can be constructed in a cosmetically acceptable format.

Magnifying Smartphone Screen Using Google Glass for Low-Vision Users

Abstract: Magnification is a key accessibility feature used by low-vision smartphone users. However, small screen size can lead to loss of context and make interaction with magnified displays challenging. We hypothesize that controlling the viewport with head motion can be natural and help in gaining access to magnified displays. We implement this idea using a Google Glass that displays the magnified smartphone screenshots received in real time via Bluetooth. Instead of navigating with touch gestures on the magnified smartphone display, the users can view different screen locations by rotating their head, and remotely interacting with the smartphone. It is equivalent to looking at a large virtual image through a head contingent viewing port, in this case, the Glass display with ~ 15 ° field of view. The system can transfer seven screenshots per second at 8 × magnification, sufficient for tasks where the display content does not change rapidly. A pilot evaluation of this approach was conducted with eight normally sighted and four visually impaired subjects performing assigned tasks using calculator and music player apps. Results showed that performance in the calculation task was faster with the Glass than with the phone's built-in screen zoom. We conclude that head contingent scanning control can be beneficial in navigating magnified small smartphone displays, at least for tasks involving familiar content layout.

Driving with Hemianopia V: Do Individuals with Hemianopia Spontaneously Adapt Their Gaze Scanning to Differing Hazard Detection Demands?

Abstract: PURPOSE We investigated whether people with homonymous hemianopia (HH) were able to spontaneously (without training or instructions) adapt their blind-side scan magnitudes in response to differing scanning requirements for detection of pedestrians in a driving simulator when differing cues about pedestrian eccentricities and movement behaviors were available in the seeing hemifield. METHODS Twelve HH participants completed two sessions in a driving simulator pressing the horn when they detected a pedestrian. Stationary pedestrians outside the driving lane were presented in one session and approaching pedestrians on a collision course in the other. Gaze data were analyzed for pedestrians initially appearing at approximately 14° in the blind hemifield. No instructions were given regarding scanning. RESULTS After appearing, the stationary pedestrians' eccentricity increased rapidly to a median of 31° after 2.5 seconds, requiring increasingly larger blind-side gaze scans for detection, while the approaching pedestrians' eccentricity remained constant at approximately 14°, requiring a more moderate scan (∼14°) for detection. Although median scan magnitudes did not differ between the two conditions (approaching: 14° [IQR 9°-15°]; stationary: 13° [IQR 9°-20°]; P = 0.43), three participants showed evidence of adapting (increasing) their blind-side scan magnitudes in the stationary condition. CONCLUSIONS Three participants (25%) appeared to be able to apply voluntary cognitive control to modify their blind-side gaze scanning in response to the differing scanning requirements of the two conditions without explicit training. TRANSLATIONAL RELEVANCE Our results suggest that only a minority of people with hemianopia are likely to be able to spontaneously adapt their blind-side scanning in response to rapidly changing and unpredictable situations in on-road driving.

Pilot Study of Gaze Scanning and Intersection Detection Failures by Drivers with Hemianopia

Abstract: In a prior study, intersection detection failures of individuals with hemianopia were strongly associated with inadequate head scanning; however, eye position was not tracked. In this pilot study, the authors tracked eye and head movements, and examined the relationship between gaze scanning and detection of pedestrians at intersections in a driving simulator. Gaze scan deficits, in particular not scanning sufficiently far into the blind hemifield, were the main reason for detection failures at the extreme edge of the clear-sight triangle in the blind hemifield. In addition, the gaze data revealed detection failures due to looked-but-failed-to-see events. The results suggest that homonymous hemianopia (HH) drivers may be at increased risk for collisions at intersections.

Development of a System to Study the Impact of Headlight Glare in a Driving Simulator

Abstract: We report on the development of a realistic dynamic simulation of oncoming headlamp glare in a driving simulator. To our knowledge, no such simulation had been attempted or achieved previously. The simulation is based on superposition of a bright LED display through a beam splitter on the simulator screen and synchronizing the illuminated LED position to the image of the simulated oncoming car. LED brightness is adjusted to result in the level of light that such headlights would cause in the driver’s eyes, enabling the testing of glare effect on drivers of different ages and impact (reduction or increase) of various vision devices.

Quantifying Visually Induced Motion Sickness (VIMS) During Stereoscopic 3D Viewing Using Temporal VIMS Rating.

Abstract: Visually induced motion sickness (VIMS) is evoked by conflicting motion sensory signals within the brain. Use of the simulator sickness questionnaire (SSQ) or postural stability measures to quantify one’s VIMS experience only measures the changes between preand post-experiment. The motion sickness susceptibility questionnaire (MSSQ) is widely used to measure individual’s sensitivity to motion sickness, but its applicability to VIMS has not been proven. We are introducing a novel VIMS susceptibility measure by combining measures of the subject’s “sensitivity” and “endurance” to VIMS. The proposed VIMS susceptibility measure was tested for various VIMS inducing conditions, and demonstrated its effectiveness by conducting both between-subjects and within-subject comparisons for different VIMS conditions. c © 2017 Society for Imaging Science and Technology. [DOI: 10.2352/J.ImagingSci.Technol.2017.61.6.060405] INTRODUCTION When viewing the contents of stereoscopic 3D (S3D) displays, observers often complain of various symptoms of discomfort, such as light-headedness, dizziness, queasiness, and nausea. Such symptoms are similar to those of motion sickness experienced in cars or boats. When they are mainly induced by visual motions, these symptoms are referred to as visually induced motion sickness (VIMS).

Simulator-Based Driving with Hemianopia: Detection Performance and Compensatory Behaviors on Approach to Intersections

Abstract: OBJECTIVES In 22 states people with homonymous hemianopia (complete loss of the visual field on the sameside in both eyes) are explicitly prohibited from driving, as they do not meet the minimum visualfield requirements for driver licensing. However, there is little scientific evidence derived eitherfrom on-road or driving simulator studies about the safety of driving with hemianopia. If the eyeand head were kept stationary, people with hemianopia would not detect anything on the side ofthe field loss. In the real world, however, they may be able to compensate for the loss byexploring the affected (blind) side using head- and eye-scanning. It has been reported that inHolland (where driving with hemianopia is permitted), driving examiners consider increasedhead-scanning (especially on approach to intersections) to be an effective compensation forperipheral visual field defects (Coeckelbergh et al., 2002). Whether increased head-scanningwhile driving results in better detection performance has never been quantitatively investigated.We conducted a simulator-based evaluation of driving with hemianopia to investigate detectionperformance and head movement behaviors on approach to intersections.METHODSTo date, eight people with complete homonymous hemianopia (5 left and 3 right), and withoutvisual neglect or significant cognitive decline have completed the study. All had current or recentdriving experience (within the last 6 years). They completed two simulator sessions, one weekapart, driving in a high-fidelity simulator. Each session consisted of a familiarization period of30-60 minutes followed by 6 test drives (each about 12 minutes in duration). The primarysimulator task was to detect and respond (by a horn press) to the appearance of pedestrian targetsin a variety of traffic situations while driving according to the normal rules of the road. Targetsappeared randomly in locations relevant to real-world driving. There were two types of targets:“roadway” targets, which appeared either on the left or right of the road at small (~ 4°) or large(~14°) eccentricities from the presumed line of sight, and “intersection” targets, which wereplaced near or at intersections to test whether drivers were scanning effectively whenapproaching an intersection. Primary outcome measures were the percentage of targets detectedand reaction times when detected. Head movements were recorded with an inexpensive, lightweight,head-mounted optical head tracking system. Preliminary analyses of head movementbehaviors were conducted for intersections with stop or yield signs. Based on visual inspectionof the head movement plots, the number and direction of head movements were recorded and head movement scanning was graded on a 4-point scale (from 1 inadequate to 4 excellent). Inaddition, we are developing methods to automatically quantify driving skills (e.g., steering, laneposition) from the simulator data output.RESULTSDetection rates for roadway pedestrian targets were lower and reaction times longer on the blindside than the seeing side (p ≤ 0.05). Blind side: median detection rate 47% (IQR 22 to 63%),median reaction time 1.65s (IQR 1.05 to 1.84s); seeing side: median detection rate 93% (IQR89% to 99%), median reaction time 0.93s, (IQR 0.88 to 1.25s). Detection rates on the blind sidewere lower at the larger eccentricity (median 23%) than the smaller eccentricity (median 66%; p= 0.01). Drivers with right hemianopia (RH) detected 83% of intersection pedestrian targets onthe extreme left of an intersection but none on the extreme right, whereas drivers with lefthemianopia (LH) detected 33% on the extreme left and 80% on the extreme right. Better headscanningscores were associated with better detection rates for intersection targets at extremepositions on the blind side (Spearman r = 0.79, p = 0.02). Two of the drivers with LH showedinadequate scanning (grade 1), failing to scan to the left at more than 60% of intersections. Therest of the drivers with LH and all three with RH demonstrated better head-scanning (grades 2-4)with some compensatory head movement behaviors. At T-intersections with no incoming roadon one side, they scanned more frequently in the direction of the “absent” road when it was onthe blind side (RH 40% and LH 80%) than when it was on the seeing side (RH and LH <10%).When there were incoming roads on both sides, the first head scan was normally to the left forLH, but it was to the right about 30% of the time for drivers with RH.CONCLUSIONSThese results provide evidence of widely varying levels of compensation and detection abilitiesamongst drivers with hemianopia, suggesting that fitness to drive should be evaluated on anindividual basis. The preliminary finding of a relationship between head-scanning score andintersection detection performance will be further evaluated using automated methods toquantify head movement behaviors and a larger sample of drivers with hemianopia. Furthermore,we will compare head movement behaviors of drivers with hemianopia to matched controldrivers without visual field loss.REFERENCESCoeckelbergh, T.R., Brouwer, W.H., Cornelissen, F.W., van Wolffelaar, P., Kooijman, A.C.(2002). The effect of visual field defects on driving performance: a driving simulator study. ArchOphthalmol, 120, 1509-1516.

The Impact of Macular Disease on Pedestrian Detection: A Driving Simulator Evaluation

Abstract: We describe the design of a driving simulator study to determine the effect of central visual field loss (due to macular disease) on pedestrian detection when driving. Pilot data suggest that a scotoma (blind area) in the central visual field can impair driving by increasing response time to hazardous circumstances.

Assessing Driving Performance with Moderate Visual Field Loss

Abstract: The minimum binocular horizontal field extent for driver licensing varies widely between states in the USA. The authors examined the relationship between visual field extent and open-road driving performance using a scoring method that measured the quality of specific skills for a range of general driving maneuvers, as well as maneuvers that the authors expected to be difficult for people with restricted fields. Twenty-eight current drivers with mild to moderate peripheral visual field restrictions (123 + or - 20 degrees, V4e target) drove the 14-mile route. While most subjects were scored as safe drivers, those with more restricted horizontal and vertical binocular field extents showed significantly poorer skills in maneuvers for which a wide field of vision is likely to be important (p < or = 0.05): speed matching when changing lanes, and maintaining lane position and keeping to the path of the curve when driving around curves. Further studies using similar assessment methods with drivers with more restricted fields are necessary to determine the minimum field extent for safe driving.

Blur Adaptation to Central Retinal Disease.

Abstract: Purpose The long-term, low-resolution vision experienced by individuals affected by retinal disease that causes central vision loss (CVL) may change their perception of blur through adaptation. This study used a short-term adaptation paradigm to evaluate adaptation to blur and sharpness in patients with CVL. Methods A variation of Webster's procedure was used to measure the point of subjective neutrality (PSN). The image that appeared normal after adaptation to each of seven blur and sharpness levels (PSN) was measured in 12 patients with CVL (20/60 to 20/320) and 5 subjects with normal sight (NS). Patients with CVL used a preferred retinal locus to view the images. Small control studies investigated the effects of long-term and medium-term (1 hour) defocus and diffusive blur. Results Adaptation was reliably measured in patients with CVL and in the peripheral vision of NS subjects. The shape of adaptation curves was similar in patients with CVL and both central and peripheral vision of NS subjects. No statistical correlations were found between adaptation and age, visual acuity, retinal eccentricity, or contrast sensitivity. Long-term blur experience by a non-CVL myopic participant caused a shift in the adaptation function. Conversely, medium-term adaptation did not cause a shift in the adaptation function. Conclusions Blur and sharp short-term adaptation occurred in peripheral vision of normal and diseased retinas. In most patients with CVL, neither adaptation nor blur perception was affected by long-term attention to peripheral low-resolution vision. The impact of blur/sharp adaptation on the benefit of image enhancement techniques for patients with CVL is discussed.

Multiplexing prism glasses for field expansion in bitemporal hemianopia

Abstract: Blind eye Nodal point Rotated MxP Overlap of see-through and expanded visual fields • Multiplexing Fresnel prism over the bridge of the nose in wrap around sunglasses • Expands visual field both by prism shift and prism minification • See-through visual field eliminates the apical scotoma Multiplexing prism glasses for field expansion in bitemporal hemianopia Jae-Hyun Jung and Eli Peli Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA 4129-A0117

A recording and analysis system of bioptic driving behaviors

Abstract: Millions of visually impaired people do not drive because they fail to meet the general vision requirements. There is a legal option in 38 US states where people with moderate central vision loss (e.g. visual acuity better than 20/200) may be permitted to drive while wearing spectacle-mounted bioptic telescopes. However, the safety of bioptic driving is still highly controversial, because bioptic use in driving is not well understood. Whether and how bioptic telescopes are actually used in driving, how they should be used appropriately, and whether their use results in better or worse driving performance has never been scientifically established. We are developing an in-car camera system that can be installed in bioptic drivers’ own vehicles to record their daily driving activities over long periods of time. Videos of the driver and traffic, GPS coordinates, XYZ acceleration, and vehicle black box data are recorded. We are also developing computer-aided reviewing techniques to automatically identify the most informative driving segments from the vast amount of data and, reconstruct the selected driving maneuvers on an interactive interface, so that these representative segments can be assessed off-line by driver evaluation and training specialists.

Driving with Para-Central Visual Field Loss: Pilot Study

Abstract: The authors studied how para-central visual field loss affects pedestrian detection in a driving simulator. Participants with para-central field loss had relatively good visual acuity (20/15 – 20/60) and 3 of 5 met local vision requirements for an unrestricted drivers license; however, they had lower detection rates and longer reaction times to pedestrians likely to appear within the blind area than in their seeing areas. They were at collision risk for 7% to 30% of pedestrians, whereas controls were at a collision risk for 0 to 4% of pedestrians.

Driving Hazard Detection with a Bioptic Telescope

Abstract: Driving by visually impaired people using bioptic telescopes is permitted in 43 states, yet their use remains controversial. One of the concerns is that the ring scotoma (blind area caused by the telescope magnification) may block the field-of-view, impacting detection of potential hazards when looking through the telescope. The authors evaluated the ability of the non-telescope eye to detect hazards in the field-of-view covered by the ring scotoma. Three participants watched a series of 54 real world driving videos that included 45 potential hazardous events and pressed a button as soon as a hazard was detected, in three conditions: just watching the videos, and while performing a reading task without or with a bioptic telescope. Results showed that all participants had either reduced detection rates or increased reaction times to hazards when performing the reading task with a bioptic telescope. These preliminary results suggest that attention demanding tasks and viewing through the telescope might impair hazard detection ability. Additional study is needed to fully understand the safety of bioptic driving.

Impact of high power and high incidence angles on peripheral prisms for homonymous hemianopia

Abstract: • Prism power varies with angle of incidence – For low-power prisms (20∆) the variations within the range of practical gaze shift (±15°) are very small – For high-power prisms (57∆) The effective deflection varies with angle of incidence, and these effects must be considered when prescribing prisms for visual field expansion • In OPS configuration – The field-of-view through the prism is wider and therefore more compressed – For 57∆ TIR blocks views beyond ≈5° into the blind side which limits the effects of scanning – Apical Scotoma is smaller (can cause diploipa) – At primary gaze the TIR on base appears in the blind hemifield while dimmer surface reflections appear at the seeing hemifield • In EPS configuration prism power and its variability are reduced – The actual prism view is slightly magnified by the reduced prism power. The effect of scanning is not limited – At primary gaze the TIR on base and the surface reflection appear in the visible hemifield and can cause visual confusion, diplopia, & bright false alarms Acknowledgement and References