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Gao Z, Hwang A, Zhai G, Peli E.
Correcting geometric distortions in stereoscopic 3D imaging. PLoS One 2018;13(10):e0205032.
AbstractMotion in a distorted virtual 3D space may cause visually induced motion sickness. Geometric distortions in stereoscopic 3D can result from mismatches among image capture, display, and viewing parameters. Three pairs of potential mismatches are considered, including 1) camera separation vs. eye separation, 2) camera field of view (FOV) vs. screen FOV, and 3) camera convergence distance (i.e., distance from the cameras to the point where the convergence axes intersect) vs. screen distance from the observer. The effect of the viewer's head positions (i.e., head lateral offset from the screen center) is also considered. The geometric model is expressed as a function of camera convergence distance, the ratios of the three parameter-pairs, and the offset of the head position. We analyze the impacts of these five variables separately and their interactions on geometric distortions. This model facilitates insights into the various distortions and leads to methods whereby the user can minimize geometric distortions caused by some parameter-pair mismatches through adjusting of other parameter pairs. For example, in postproduction, viewers can correct for a mismatch between camera separation and eye separation by adjusting their distance from the real screen and changing the effective camera convergence distance.
García-Pérez MA, Peli E.
Aniseikonia Tests: The Role of Viewing Mode, Response Bias, and Size-Color Illusions. Transl Vis Sci Technol 2015;4(3):9.
AbstractPURPOSE: To identify the factors responsible for the poor validity of the most common aniseikonia tests, which involve size comparisons of red-green stimuli presented haploscopically. METHODS: Aniseikonia was induced by afocal size lenses placed before one eye. Observers compared the sizes of semicircles presented haploscopically via color filters. The main factor under study was viewing mode (free viewing versus short presentations under central fixation). To eliminate response bias, a three-response format allowed observers to respond if the left, the right, or neither semicircle appeared larger than the other. To control decisional (criterion) bias, measurements were taken with the lens-magnified stimulus placed on the left and on the right. To control for size-color illusions, measurements were made with color filters in both arrangements before the eyes and under binocular vision (without color filters). RESULTS: Free viewing resulted in a systematic underestimation of lens-induced aniseikonia that was absent with short presentations. Significant size-color illusions and decisional biases were found that would be mistaken for aniseikonia unless appropriate action is taken. CONCLUSIONS: To improve their validity, aniseikonia tests should use short presentations and include control conditions to prevent contamination from decisional/response biases. If anaglyphs are used, presence of size-color illusions must be checked for. TRANSLATIONAL RELEVANCE: We identified optimal conditions for administration of aniseikonia tests and appropriate action for differential diagnosis of aniseikonia in the presence of response biases or size-color illusions. Our study has clinical implications for aniseikonia management.
Goldstein JE, Guo X, Swenor BK, Boland MV, Smith K.
Using Electronic Clinical Decision Support to Examine Vision Rehabilitation Referrals and Practice Guidelines in Ophthalmology. Transl Vis Sci Technol 2022;11(10):8.
AbstractPurpose: To examine ophthalmologist use of an electronic health record (EHR)-based clinical decision support system (CDSS) to facilitate low vision rehabilitation (LVR) care referral. Methods: The CDSS alert was designed to appear when best documented visual acuity was <20/40 or hemianopia or quadrantanopia diagnosis was identified during an ophthalmology encounter from November 6, 2017, to April 5, 2019. Fifteen ophthalmologists representing eight subspecialties from an academic medical center were required to respond to the referral recommendation (order, don't order). LVR referral rates and ophthalmologist user experience were assessed. Encounter characteristics associated with LVR referrals were explored using multilevel logistic regression analysis. Results: The alert appeared for 3625 (8.9%) of 40,931 eligible encounters. The referral rate was 14.8% (535/3625). Of the 3413 encounters that met the visual acuity criterion only, patients who were worse than 20/60 were more likely to be referred, and 32.4% of referred patients were between 20/40 and 20/60. Primary reasons for deferring referrals included active medical or surgical treatment, refractive-related issues, and previous connection to LVR services. Eleven of the 13 ophthalmologists agreed that the alert was useful in identifying candidates for LVR services. Conclusions: A CDSS for patient identification and referral offers an acceptable mechanism to apply practice guidelines and prompt ophthalmologists to facilitate LVR care. Further study is warranted to optimize ophthalmologist user experience while refining alert criteria beyond visual acuity. Translational Relevance: The CDSS provides the framework for multi-center research to assess the development of pragmatic algorithms and standards for facilitating LVR care.
Goldstein JE, Jackson ML, Fox SM, Deremeik JT, Massof RW, Massof RW.
Clinically Meaningful Rehabilitation Outcomes of Low Vision Patients Served by Outpatient Clinical Centers. JAMA Ophthalmol 2015;133(7):762-9.
AbstractIMPORTANCE: To facilitate comparative clinical outcome research in low vision rehabilitation, we must use patient-centered measurements that reflect clinically meaningful changes in visual ability. OBJECTIVE: To quantify the effects of currently provided low vision rehabilitation (LVR) on patients who present for outpatient LVR services in the United States. DESIGN, SETTING, AND PARTICIPANTS: Prospective, observational study of new patients seeking outpatient LVR services. From April 2008 through May 2011, 779 patients from 28 clinical centers in the United States were enrolled in the Low Vision Rehabilitation Outcomes Study. The Activity Inventory, a visual function questionnaire, was administered to measure overall visual ability and visual ability in 4 functional domains (reading, mobility, visual motor function, and visual information processing) at baseline and 6 to 9 months after usual LVR care. The Geriatric Depression Scale, Telephone Interview for Cognitive Status, and Medical Outcomes Study 36-Item Short-Form Health Survey physical functioning questionnaires were also administered to measure patients' psychological, cognitive, and physical health states, respectively, and clinical findings of patients were provided by study centers. MAIN OUTCOMES AND MEASURES: Mean changes in the study population and minimum clinically important differences in the individual in overall visual ability and in visual ability in 4 functional domains as measured by the Activity Inventory. RESULTS: Baseline and post-rehabilitation measures were obtained for 468 patients. Minimum clinically important differences (95% CIs) were observed in nearly half (47% [95% CI, 44%-50%]) of patients in overall visual ability. The prevalence rates of patients with minimum clinically important differences in visual ability in functional domains were reading (44% [95% CI, 42%-48%]), visual motor function (38% [95% CI, 36%-42%]), visual information processing (33% [95% CI, 31%-37%]), and mobility (27% [95% CI, 25%-31%]). The largest average effect size (Cohen d = 0.87) for the population was observed in overall visual ability. Age (P = .006) was an independent predictor of changes in overall visual ability, and logMAR visual acuity (P = .002) was predictive of changes in visual information processing. CONCLUSIONS AND RELEVANCE: Forty-four to fifty percent of patients presenting for outpatient LVR show clinically meaningful differences in overall visual ability after LVR, and the average effect sizes in overall visual ability are large, close to 1 SD.
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Han S'E, Kim S, Jung J-H.
The effect of visual rivalry in peripheral head-mounted displays on mobility. Sci Rep 2023;13(1):20199.
AbstractRecent head-mounted displays and smart glasses use vision multiplexing, an optical approach where two or more views are superimposed on each other. In vision multiplexing, augmented information is presented over an observer's natural field of view, providing field expansion and critical information during mobility situations like walking and driving. Yet despite its utility, vision multiplexing may produce visual rivalry, a phenomenon where perception alternates between the augmented information and the background scene for seconds at a time. To investigate, we compared the effect of different peripheral vision multiplexing configurations (unilateral opaque, unilateral see-through and bilateral see-through) on the detection of augmented information, incorporating at the same time real-world characteristics (target eccentricity, depth condition, and gaze movement) for a more realistic assessment. Results showed a persistently lower target detection rate in unilateral configurations than the bilateral configuration, suggesting a larger effect of binocular rivalry on target visibility. Nevertheless, this effect does become attenuated when more naturalistic elements are incorporated, and we discuss recommendations for vision multiplexing design and possible avenues for further research.
Han S'E, Qiu C, Lee KR, Jung J-H, Peli E.
Word recognition: re-thinking prosthetic vision evaluation. J Neural Eng 2018;15(5):055003.
AbstractOBJECTIVE: Evaluations of vision prostheses and sensory substitution devices have frequently relied on repeated training and then testing with the same small set of items. These multiple forced-choice tasks produced above chance performance in blind users, but it is unclear if the observed performance represents restoration of vision that transfers to novel, untrained items. APPROACH: Here, we tested the generalizability of the forced-choice paradigm on discrimination of low-resolution word images. Extensive visual training was conducted with the same 10 words used in previous BrainPort tongue stimulation studies. The performance on these 10 words and an additional 50 words was measured before and after the training sessions. MAIN RESULTS: The results revealed minimal performance improvement with the untrained words, demonstrating instead pattern discrimination limited mostly to the trained words. SIGNIFICANCE: These findings highlight the need to reconsider current evaluation practices, in particular, the use of forced-choice paradigms with a few highly trained items. While appropriate for measuring the performance thresholds in acuity or contrast sensitivity of a functioning visual system, performance on such tasks cannot be taken to indicate restored spatial pattern vision.
Haun AM, Peli E.
Similar Sensitivity to Ladder Contours in Macular Degeneration Patients and Controls. PLoS One 2015;10(7):e0128119.
AbstractPURPOSE: To determine whether people with central field loss (CFL) from macular degeneration have improved ability to recognize a particularly difficult spatial configuration embedded in noise, the peripherally-viewed 'ladder contour'. The visibility of these configuration has been linked to general contour integration ability and crowding limitations in peripheral vision. METHODS: We used a trial-based yes-no task. CFL patients and normally-sighted controls performed the task, looking for ladder contours embedded in a field of randomly oriented Gabor patches, at a range of stimulus presentation times (varying stimulus difficulty). Viewing eccentricity in CFL patients was set by their preferred retinal loci (PRLs) and matched artificially in the control group. The contours were presented so as to be tangent to the CFL region, given a patient's PRL location. RESULTS: CFL and normally-sighted groups performed similarly on the task. The only significant determinant of performance was the viewing eccentricity. CONCLUSIONS: CFL patients do not seem to develop any improved ability to recognize ladder contours with their parafoveal retina, which suggests that there is no underlying improvement in contour integration or reduction in crowding limitations in the region of the PRL despite extended daily use.
Hecht H, Hörichs J, Sheldon S, Quint J, Bowers A.
The effects of simulated vision impairments on the cone of gaze. Atten Percept Psychophys 2015;77(7):2399-408.
AbstractDetecting the gaze direction of others is critical for many social interactions. We explored factors that may make the perception of mutual gaze more difficult, including the degradation of the stimulus and simulated vision impairment. To what extent do these factors affect the complex assessment of mutual gaze? Using an interactive virtual head whose eye direction could be manipulated by the subject, we conducted two experiments to assess the effects of simulated vision impairments on mutual gaze. Healthy subjects had to demarcate the center and the edges of the cone of gaze-that is, the range of gaze directions that are accepted for mutual gaze. When vision was impaired by adding a semitransparent white contrast reduction mask to the display (Exp. 1), judgments became more variable and more influenced by the head direction (indicative of a compensation strategy). When refractive blur was added (Exp. 1), the gaze cone shrank from 12.9° (no blur) to 11.3° (3-diopter lens), which cannot be explained by a low-level process but might reflect a tightening of the criterion for mutual gaze as a response to the increased uncertainty. However, the overall effects of the impairments were relatively modest. Elderly subjects (Exp. 2) produced more variability but did not differ qualitatively from the younger subjects. In the face of artificial vision impairments, compensation mechanisms and criterion changes allow us to perform better in mutual gaze perception than would be predicted by a simple extrapolation from the losses in basic visual acuity and contrast sensitivity.
Hoogsteen KMP, Szpiro S, Kreiman G, Peli E.
Beyond the Cane: Describing Urban Scenes to Blind People for Mobility Tasks. ACM Trans Access Comput 2022;15(3)
AbstractBlind people face difficulties with independent mobility, impacting employment prospects, social inclusion, and quality of life. Given the advancements in computer vision, with more efficient and effective automated information extraction from visual scenes, it is important to determine what information is worth conveying to blind travelers, especially since people have a limited capacity to receive and process sensory information. We aimed to investigate which objects in a street scene are useful to describe and how those objects should be described. Thirteen cane-using participants, five of whom were early blind, took part in two urban walking experiments. In the first experiment, participants were asked to voice their information needs in the form of questions to the experimenter. In the second experiment, participants were asked to score scene descriptions and navigation instructions, provided by the experimenter, in terms of their usefulness. The descriptions included a variety of objects with various annotations per object. Additionally, we asked participants to rank order the objects and the different descriptions per object in terms of priority and explain why the provided information is or is not useful to them. The results reveal differences between early and late blind participants. Late blind participants requested information more frequently and prioritized information about objects' locations. Our results illustrate how different factors, such as the level of detail, relative position, and what type of information is provided when describing an object, affected the usefulness of scene descriptions. Participants explained how they (indirectly) used information, but they were frequently unable to explain their ratings. The results distinguish between various types of travel information, underscore the importance of featuring these types at multiple levels of abstraction, and highlight gaps in current understanding of travel information needs. Elucidating the information needs of blind travelers is critical for the development of more useful assistive technologies.
Houston KE, Paschalis EI, Angueira DC, Bronstad MP, Barrett AM, Iaccarino MA.
Restoration of Vision After Brain Injury Using Magnet Glasses. Am J Phys Med Rehabil 2017;96(4):e70-e74.
AbstractVisual impairments are common after traumatic brain injury (TBI) and negatively affect quality of life. We describe a 39-year-old woman with a severe TBI who was evaluated by the inpatient optometry and vision rehabilitation service with findings of complete right homonymous hemianopia and right cranial nerve III palsy with 30-degree right exotropia (eye turn out) and complete right ptosis (eyelid will not open). The 30-degree exotropia advantageously generated 30 degrees of right visual field expansion when the right ptosis was treated with a magnetic levator prosthesis, which restores eyelid opening. Once opened, the patient used visual field expansion derived from a right exotropia to overcome functional impairments caused by right hemianopia. Field expansion improved the patient's wheelchair mobility and reaching tasks during inpatient therapy. This is the first report of visual field expansion by strabismus facilitated by correction of ptosis. Strabismus should be considered for its potential field expansion benefits when homonymous visual deficits are present, before considering patching. A multidisciplinary vision rehabilitation team is well suited to make this determination.
Houston KE, Keilty M, Collins C, Trehan R, Mouldovan T, Stuckart K, Engelhardt N, Nadeau M, Rovito CA, Merabet LB.
Development and 5-year Evaluation of Diagnosis-Specific Protocols for Visual Neuro-Rehabilitation in a Multicenter Inpatient Rehabilitation Network. Arch Rehabil Res Clin Transl 2023;5(1):100246.
AbstractOBJECTIVE: To provide a retrospective evaluation of a new eye and vision rehabilitation care pathway in a U.S. multi-site inpatient rehabilitation network involving the occupational therapy (OT) staff and a consulting doctor of optometry (OD) specializing in vision rehabilitation. DESIGN: Retrospective study. SETTING: Two Inpatient Rehabilitation Facilities (IRFs) and 1 Long Term Acute Care Hospital (LTACH). PARTICIPANTS: There were 2083 records reviewed (44% women, avg. age 59 years). The most common diagnoses were hemispatial neglect (19.2%), homonymous field defects (18.5%), and oculomotor cranial nerve palsies (16.7%) (N=2083). INTERVENTIONS: Clinical care was reviewed where diagnosis-specific protocols were developed and training was provided to OTs in order to reinforce OD-prescribed interventions during daily treatment sessions, including (1) third, fourth, and sixth ocular cranial nerve palsies (OCNPs) with prisms fitted for full time, postural adaptation training, and oculomotor re-education using pursuits, saccades, head-rotations, and binocular vision exercises including alternate cover and vergence; (2) homonymous hemianopia with training awareness of field loss, eccentric viewing, and fitting of Peli lens for optical field expansion; and (3) prism adaptation therapy (PAT) for left hemispatial neglect. MAIN OUTCOME MEASURES: Frequency of diagnoses. HYPOTHESIS: Diagnoses with developed protocols were most common. Secondarily, feasibility and efficacy by anonymous OT survey. RESULTS: 2083 vision consults were performed over 5 years. The most common diagnoses were hemispatial neglect (n=399, 19.2%), homonymous field defects (n=386, 18.5%), and OCNPs (n=347, 16.7%). None of the OTs reported the protocols were infeasible and 63% (IQR 38%-69%) reported their patients benefited from the interventions. The survey suggested prism for OCNPs helped in 42%, and Peli lens and PAT both helped in 38%. CONCLUSIONS: Data support the feasibility of this inpatient eye and vision rehabilitation care pathway which may be used as a foundation for creating or refining similar programs elsewhere. Uniform administration of IRF-based visual neuro-rehabilitation care could provide a substrate for future clinical trials to evaluate efficacy.
Houston KE, Paschalis EI.
Feasibility of Magnetic Levator Prosthesis Frame Customization Using Craniofacial Scans and 3-D Printing. Transl Vis Sci Technol 2022;11(10):34.
AbstractPurpose: To determine the feasibility of a custom frame generation approach for nonsurgical management of severe blepharoptosis with the magnetic levator prosthesis (MLP). Methods: Participants (n = 8) with severe blepharoptosis (obscuring the visual axis) in one or both eyes who had previously been using a non-custom MLP had a craniofacial scan with a smartphone app to generate a custom MLP frame. A magnetic adhesive was attached to the affected eyelid. The custom MLP frame held a cylindrical magnet near the eyebrow above the affected eyelid, suspending it in the magnetic field while still allowing blinking. The spectacle magnet could be rotated manually, providing adjustable force via angular translation of the magnetic field. Fitting success and comfort were recorded, and interpalpebral fissure (IPF) was measured from video frames after 20 minutes in-office and one-week at-home use. Preference was documented, custom versus non-custom. Results: Overall, 88% of patients (7/8) were successfully fitted with a median 9/10 comfort (interquartile 7-10) and median ptosis improvement of 2.3 mm (1.3-5.0); P = 0.01). Exact binomial testing suggested, with 80% power, that the true population success rate was significantly greater than 45% (P = 0.05). Five participants took the custom MLP home for one week, with only one case of mild conjunctival redness which resolved without treatment. Highest to lowest force modulation resulted in a marginally significant median IPF adjustment of 1.5 mm (0.8 to 2.7; P = 0.06). All preferred the custom frame. Conclusions: The three-dimensional custom MLP frame generation approach using a smartphone app-based craniofacial scan is a feasible approach for clinical deployment of the MLP. Translational Relevance: First demonstration of customized frame generation for the MLP.
Houston KE, Barrett AM.
Patching for Diplopia Contraindicated in Patients with Brain Injury?. Optom Vis Sci 2017;94(1):120-124.
AbstractPURPOSE: Patching for double vision is a common palliative treatment for head-trauma patients with acquired strabismus when prisms are not feasible. METHODS: We review literature on spatial neglect and discuss possible effects of monocular occlusion on spatial attention. RESULTS: Patching the left eye has been shown to worsen spatial judgments in some brain-injured patients with left neglect by inhibiting the right superior colliculus further impairing contralateral leftward orienting (the Sprague Effect). CONCLUSIONS: Because more peripheral parts of the visual field increasingly project to the contralateral superior colliculus with the temporal crescent being entirely contralateral, avoiding patching of the temporal crescent was advised, and in most cases can be achieved by taping off the spectacle lens and avoiding an elastic eye patch.
Houston KE, Nadeau M, Paschalis EI.
Clinical Report: Clinician Feedback on the Magnetic Levator Prosthesis. Optom Vis Sci 2023;
AbstractSIGNIFICANCE: Stakeholder engagement has been identified by national health organizations as a crucial step to successful translation of new healthcare treatments. In this clinical report, clinician-stakeholder feedback is presented for the Magnetic Levator Prosthesis (MLP), a promising non-invasive spectacle device which restores eyelid motility with magnetic force. PURPOSE: To evaluate MLP clinical need and translational barriers. METHODS: Ten vision rehabilitation optometrists who attended an educational presentation on the MLP and participated in a hands-on workshop in the fitting of a patient were invited to complete an anonymous online survey. Ten multiple-choice items gathered data on estimated patient need, current approaches, main barriers for MLP, temporary versus chronic use, cost barriers, and need for insurance coverage. Open fields allowed for additional comments. RESULTS: Nine of 10 specialists completed the survey. Of those, 7 answered that they could potentially see at least 1-5 patients for ptosis management within a year. The most common ptosis management options reported were the ptosis crutch, taping the eyelid open, and Oxymetazoline drops, all with 6 responses each. Seven clinicians indicated that cost was a main concern. If cost-to-patient was not a barrier, all indicated they would be at least somewhat likely to try the MLP for: 1) temporary management of ptosis, 2) as a pre-surgical trial, and 3) for long term management of ptosis, with more selecting extremely likely and very likely than somewhat likely. Main comments were expressing enthusiasm for the technology and that it would be more appealing for patients if covered by insurance. CONCLUSIONS: This clinical report suggests the main barriers to clinical success of the MLP may be cost and insurance coverage, appearance of the device, and self-application. Possible solutions are cost-benefit analysis research, engineering efforts to reduce spectacle magnet size and improve the ease of eyelid magnet application.
Houston KE, Peli E, Goldstein RB, Bowers AR.
Driving With Hemianopia VI: Peripheral Prisms and Perceptual-Motor Training Improve Detection in a Driving Simulator. Transl Vis Sci Technol 2018;7(1):5.
AbstractPurpose: Drivers with homonymous hemianopia (HH) were previously found to have impaired detection of blind-side hazards, yet in many jurisdictions they may obtain a license. We evaluated whether oblique 57Δ peripheral prisms (p-prisms) and perceptual-motor training improved blind-side detection rates. Methods: Patients with HH (n = 11) wore p-prisms for 2 weeks and then received perceptual-motor training (six visits) detecting and touching stimuli in the prism-expanded vision. In a driving simulator, patients drove and pressed the horn upon detection of pedestrians who ran toward the roadway (26 from each side): (1) without p-prisms at baseline; (2) with p-prisms after 2 weeks acclimation but before training; (3) with p-prisms after training; and (4) 3 months later. Results: P-prisms improved blind-side detection from 42% to 56%, which further improved after training to 72% (all P < 0.001). Blind-side timely responses (adequate time to have stopped) improved from 31% without to 44% with p-prisms (P < 0.001) and further improved with training to 55% (P = 0.02). At the 3-month follow-up, improvements from training were maintained for detection (65%; P = 0.02) but not timely responses (P = 0.725). There was wide between-subject variability in baseline detection performance and response to p-prisms. There were no negative effects of p-prisms on vehicle control or seeing-side performance. Conclusions: P-prisms improved detection with no negative effects, and training may provide additional benefit. Translational Relevance: In jurisdictions where people with HH are legally driving, these data aid in clinical decision making by providing evidence that p-prisms improve performance without negative effects.
Houston KE, Bowers AR, Peli E, Woods RL.
Peripheral Prisms Improve Obstacle Detection during Simulated Walking for Patients with Left Hemispatial Neglect and Hemianopia. Optom Vis Sci 2018;95(9):795-804.
AbstractSIGNIFICANCE: The first report on the use of peripheral prisms (p-prisms) for patients with left neglect and homonymous visual field defects (HVFDs). PURPOSE: The purpose of this study was to investigate if patients with left hemispatial neglect and HVFDs benefit from p-prisms to expand the visual field and improve obstacle detection. METHODS: Patients (24 with HVFDs, 10 of whom had left neglect) viewed an animated, virtual, shopping mall corridor and reported if they would have collided with a human obstacle that appeared at various offsets up to 13.5° from their simulated walking path. There were 40 obstacle presentations on each side, with and without p-prisms. No training with p-prisms was provided, and gaze was fixed at the center of expansion. RESULTS: Detection on the side of the HVFD improved significantly with p-prisms in both groups, from 26 to 92% in the left-neglect group and 43 to 98% in the non-neglect group (both P < .001). There was a tendency for greater improvement in the neglect patients with p-prisms. For collision judgments, both groups exhibited a large increase in perceived collisions on the side of the HVFD with the prisms (P < .001), with no difference between the groups (P = .93). Increased perceived collisions represent a wider perceived safety margin on the side of the HVFD. CONCLUSIONS: Within the controlled conditions of this simulated, collision judgment task, patients with left neglect responded well to initial application of p-prisms exhibiting improved detection and wider safety margins on the side of the HVFD that did not differ from non-neglect patients. Further study of p-prisms for neglect patients in free-gaze conditions after extended wear and in real-world mobility tasks is clearly warranted.
