1
|
Schmetterer L, Scholl H, Garhöfer G, Janeschitz-Kriegl L, Corvi F, Sadda SR, Medeiros FA. Endpoints for clinical trials in ophthalmology. Prog Retin Eye Res 2023; 97:101160. [PMID: 36599784 DOI: 10.1016/j.preteyeres.2022.101160] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 12/22/2022] [Accepted: 12/28/2022] [Indexed: 01/03/2023]
Abstract
With the identification of novel targets, the number of interventional clinical trials in ophthalmology has increased. Visual acuity has for a long time been considered the gold standard endpoint for clinical trials, but in the recent years it became evident that other endpoints are required for many indications including geographic atrophy and inherited retinal disease. In glaucoma the currently available drugs were approved based on their IOP lowering capacity. Some recent findings do, however, indicate that at the same level of IOP reduction, not all drugs have the same effect on visual field progression. For neuroprotection trials in glaucoma, novel surrogate endpoints are required, which may either include functional or structural parameters or a combination of both. A number of potential surrogate endpoints for ophthalmology clinical trials have been identified, but their validation is complicated and requires solid scientific evidence. In this article we summarize candidates for clinical endpoints in ophthalmology with a focus on retinal disease and glaucoma. Functional and structural biomarkers, as well as quality of life measures are discussed, and their potential to serve as endpoints in pivotal trials is critically evaluated.
Collapse
Affiliation(s)
- Leopold Schmetterer
- Singapore Eye Research Institute, Singapore; SERI-NTU Advanced Ocular Engineering (STANCE), Singapore; Academic Clinical Program, Duke-NUS Medical School, Singapore; School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, Singapore; Department of Clinical Pharmacology, Medical University Vienna, Vienna, Austria; Center for Medical Physics and Biomedical Engineering, Medical University Vienna, Vienna, Austria; Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland.
| | - Hendrik Scholl
- Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland; Department of Ophthalmology, University of Basel, Basel, Switzerland
| | - Gerhard Garhöfer
- Department of Clinical Pharmacology, Medical University Vienna, Vienna, Austria
| | - Lucas Janeschitz-Kriegl
- Institute of Molecular and Clinical Ophthalmology, Basel, Switzerland; Department of Ophthalmology, University of Basel, Basel, Switzerland
| | - Federico Corvi
- Eye Clinic, Department of Biomedical and Clinical Sciences "Luigi Sacco", University of Milan, Italy
| | - SriniVas R Sadda
- Doheny Eye Institute, Los Angeles, CA, USA; Department of Ophthalmology, David Geffen School of Medicine at University of California, Los Angeles, CA, USA
| | - Felipe A Medeiros
- Vision, Imaging and Performance Laboratory, Department of Ophthalmology, Duke Eye Center, Duke University, Durham, NC, USA
| |
Collapse
|
2
|
Kasowski J, Johnson BA, Neydavood R, Akkaraju A, Beyeler M. A systematic review of extended reality (XR) for understanding and augmenting vision loss. J Vis 2023; 23:5. [PMID: 37140911 PMCID: PMC10166121 DOI: 10.1167/jov.23.5.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 04/04/2023] [Indexed: 05/05/2023] Open
Abstract
Over the past decade, extended reality (XR) has emerged as an assistive technology not only to augment residual vision of people losing their sight but also to study the rudimentary vision restored to blind people by a visual neuroprosthesis. A defining quality of these XR technologies is their ability to update the stimulus based on the user's eye, head, or body movements. To make the best use of these emerging technologies, it is valuable and timely to understand the state of this research and identify any shortcomings that are present. Here we present a systematic literature review of 227 publications from 106 different venues assessing the potential of XR technology to further visual accessibility. In contrast to other reviews, we sample studies from multiple scientific disciplines, focus on technology that augments a person's residual vision, and require studies to feature a quantitative evaluation with appropriate end users. We summarize prominent findings from different XR research areas, show how the landscape has changed over the past decade, and identify scientific gaps in the literature. Specifically, we highlight the need for real-world validation, the broadening of end-user participation, and a more nuanced understanding of the usability of different XR-based accessibility aids.
Collapse
Affiliation(s)
- Justin Kasowski
- Graduate Program in Dynamical Neuroscience, University of California, Santa Barbara, CA, USA
| | - Byron A Johnson
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, CA, USA
| | - Ryan Neydavood
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, CA, USA
| | - Anvitha Akkaraju
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, CA, USA
| | - Michael Beyeler
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, CA, USA
- Department of Computer Science, University of California, Santa Barbara, CA, USA
| |
Collapse
|
3
|
Yücel EI, Sadeghi R, Kartha A, Montezuma SR, Dagnelie G, Rokem A, Boynton GM, Fine I, Beyeler M. Factors affecting two-point discrimination in Argus II patients. Front Neurosci 2022; 16:901337. [PMID: 36090266 PMCID: PMC9448992 DOI: 10.3389/fnins.2022.901337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 07/11/2022] [Indexed: 11/13/2022] Open
Abstract
Two of the main obstacles to the development of epiretinal prosthesis technology are electrodes that require current amplitudes above safety limits to reliably elicit percepts, and a failure to consistently elicit pattern vision. Here, we explored the causes of high current amplitude thresholds and poor spatial resolution within the Argus II epiretinal implant. We measured current amplitude thresholds and two-point discrimination (the ability to determine whether one or two electrodes had been stimulated) in 3 blind participants implanted with Argus II devices. Our data and simulations show that axonal stimulation, lift and retinal damage all play a role in reducing performance in the Argus 2, by either limiting sensitivity and/or reducing spatial resolution. Understanding the relative role of these various factors will be critical for developing and surgically implanting devices that can successfully subserve pattern vision.
Collapse
Affiliation(s)
- Ezgi I. Yücel
- Department of Psychology, University of Washington, Seattle, WA, United States
| | - Roksana Sadeghi
- Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Arathy Kartha
- Department of Ophthalmology, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Sandra Rocio Montezuma
- Department of Ophthalmology and Visual Neurosciences, University of Minnesota, Minneapolis, MN, United States
| | - Gislin Dagnelie
- Department of Ophthalmology, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Ariel Rokem
- Department of Psychology, University of Washington, Seattle, WA, United States,eScience Institute, University of Washington, Seattle, WA, United States
| | - Geoffrey M. Boynton
- Department of Psychology, University of Washington, Seattle, WA, United States
| | - Ione Fine
- Department of Psychology, University of Washington, Seattle, WA, United States,*Correspondence: Ione Fine,
| | - Michael Beyeler
- Department of Computer Science, University of California, Santa Barbara, Santa Barbara, CA, United States,Department of Psychological and Brain Sciences, University of California, Santa Barbara, Santa Barbara, CA, United States
| |
Collapse
|
4
|
Christie B, Sadeghi R, Kartha A, Caspi A, Tenore FV, Klatzky RL, Dagnelie G, Billings S. Sequential epiretinal stimulation improves discrimination in simple shape discrimination tasks only. J Neural Eng 2022; 19. [PMID: 35613043 DOI: 10.1088/1741-2552/ac7326] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 05/24/2022] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Electrical stimulation of the retina can elicit flashes of light called phosphenes, which can be used to restore rudimentary vision for people with blindness. Functional sight requires stimulation of multiple electrodes to create patterned vision, but phosphenes tend to merge together in an uninterpretable way. Sequentially stimulating electrodes in human visual cortex has recently demonstrated that shapes could be "drawn" with better perceptual resolution relative to simultaneous stimulation. The goal of this study was to evaluate if sequential stimulation would also form clearer shapes when the retina is the neural target. APPROACH Two human participants with retinitis pigmentosa who had Argus® II retinal prostheses participated in this study. We evaluated different temporal parameters for sequential stimulation in phosphene shape mapping and forced-choice discrimination tasks. For the discrimination tasks, performance was compared between stimulating electrodes simultaneously versus sequentially. MAIN RESULTS Phosphenes elicited by different electrodes were reported as vastly different shapes. Sequential electrode stimulation outperformed simultaneous stimulation in simple discrimination tasks, in which shapes were created by stimulating 3-4 electrodes, but not in more complex discrimination tasks involving 5+ electrodes. For sequential stimulation, the optimal pulse train duration was 200 ms when stimulating at 20 Hz and the optimal gap interval was tied between 0 and 50 ms. Efficacy of sequential stimulation also depended strongly on selecting electrodes that elicited phosphenes with similar shapes and sizes. SIGNIFICANCE An epiretinal prosthesis can produce coherent simple shapes with a sequential stimulation paradigm, which can be used as rudimentary visual feedback. However, success in creating more complex shapes, such as letters of the alphabet, is still limited. Sequential stimulation may be most beneficial for epiretinal prostheses in simple tasks, such as basic navigation, rather than complex tasks such as object identification.
Collapse
Affiliation(s)
- Breanne Christie
- Research and Exploratory Development Department, Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, Maryland, 20723, UNITED STATES
| | - Roksana Sadeghi
- Department of Biomedical Engineering, Johns Hopkins School of Medicine, 733 N Broadway, Baltimore, Maryland, 21205, UNITED STATES
| | - Arathy Kartha
- Department of Ophthalmology, Johns Hopkins School of Medicine, 1800 Orleans St., Baltimore, Maryland, 21287, UNITED STATES
| | - Avi Caspi
- Jerusalem College of Technology, Ha-Va'ad ha-Le'umi St 21, Jerusalem, 91160, ISRAEL
| | - Francesco V Tenore
- Research and Exploratory Development Department, Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, Maryland, 20723, UNITED STATES
| | - Roberta L Klatzky
- Department of Psychology, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, Pennsylvania, 15213-3815, UNITED STATES
| | - Gislin Dagnelie
- Department of Ophthalmology, Johns Hopkins School of Medicine, 1800 Orleans St., Baltimore, Maryland, 21287, UNITED STATES
| | - Seth Billings
- Research and Exploratory Development Department, Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, Maryland, 20723-6005, UNITED STATES
| |
Collapse
|
5
|
Kasowski J, Beyeler M. Immersive Virtual Reality Simulations of Bionic Vision. AUGMENTED HUMANS 2022 2022; 2022:82-93. [PMID: 35856703 PMCID: PMC9289996 DOI: 10.1145/3519391.3522752] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Bionic vision uses neuroprostheses to restore useful vision to people living with incurable blindness. However, a major outstanding challenge is predicting what people "see" when they use their devices. The limited field of view of current devices necessitates head movements to scan the scene, which is difficult to simulate on a computer screen. In addition, many computational models of bionic vision lack biological realism. To address these challenges, we present VR-SPV, an open-source virtual reality toolbox for simulated prosthetic vision that uses a psychophysically validated computational model to allow sighted participants to "see through the eyes" of a bionic eye user. To demonstrate its utility, we systematically evaluated how clinically reported visual distortions affect performance in a letter recognition and an immersive obstacle avoidance task. Our results highlight the importance of using an appropriate phosphene model when predicting visual outcomes for bionic vision.
Collapse
|
6
|
Avraham D, Jung JH, Yitzhaky Y, Peli E. Retinal prosthetic vision simulation: temporal aspects. J Neural Eng 2021; 18. [PMID: 34359062 DOI: 10.1088/1741-2552/ac1b6c] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 08/06/2021] [Indexed: 11/11/2022]
Abstract
Objective. The perception of individuals fitted with retinal prostheses is not fully understood, although several retinal implants have been tested and commercialized. Realistic simulations of perception with retinal implants would be useful for future development and evaluation of such systems.Approach.We implemented a retinal prosthetic vision simulation, including temporal features, which have not been previously simulated. In particular, the simulation included temporal aspects such as persistence and perceptual fading of phosphenes and the electrode activation rate.Main results.The simulated phosphene persistence showed an effective reduction in flickering at low electrode activation rates. Although persistence has a positive effect on static scenes, it smears dynamic scenes. Perceptual fading following continuous stimulation affects prosthetic vision of both static and dynamic scenes by making them disappear completely or partially. However, we showed that perceptual fading of a static stimulus might be countered by head-scanning motions, which together with the persistence revealed the contours of the faded object. We also showed that changing the image polarity may improve simulated prosthetic vision in the presence of persistence and perceptual fading.Significance.Temporal aspects have important roles in prosthetic vision, as illustrated by the simulations. Considering these aspects may improve the future design, the training with, and evaluation of retinal prostheses.
Collapse
Affiliation(s)
- David Avraham
- Department of Electro-Optical Engineering, School of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel.,Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, United States of America
| | - Jae-Hyun Jung
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, United States of America
| | - Yitzhak Yitzhaky
- Department of Electro-Optical Engineering, School of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Eli Peli
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, United States of America
| |
Collapse
|
7
|
Sadeghi R, Kartha A, Barry MP, Bradley C, Gibson P, Caspi A, Roy A, Dagnelie G. Glow in the dark: Using a heat-sensitive camera for blind individuals with prosthetic vision. Vision Res 2021; 184:23-29. [PMID: 33780753 PMCID: PMC8137663 DOI: 10.1016/j.visres.2021.02.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 02/12/2021] [Accepted: 02/28/2021] [Indexed: 11/29/2022]
Abstract
To date, retinal implants are the only available treatment for blind individuals with retinal degenerations such as retinitis pigmentosa. Argus II is the only visual implant with FDA approval, with more than 300 users worldwide. Argus II stimulation is based on a grayscale image coming from a head-mounted visible-light camera. Normally, the 11°×19° field of view of the Argus II user is full of objects that may elicit similar phosphenes. The prosthesis cannot meaningfully convey so much visual information, and the percept is reduced to an ambiguous impression of light. This study is aimed at investigating the efficacy of simplifying the video input in real-time using a heat-sensitive camera. Data were acquired from four Argus II users in 5 stationary tasks with either hot objects or human targets as stimuli. All tasks were of m-alternative forced choice design where precisely one of the m≥2 response alternatives was defined to be "correct" by the experimenter. To compare performance with heat-sensitive and normal cameras across all tasks, regardless of m, we used an extension of signal detection theory to latent variables, estimating person ability and item difficulty in d' units. Results demonstrate that subject performance was significantly better across all tasks with the thermal camera compared to the regular Argus II camera. The future addition of thermal imaging to devices with very poor spatial resolution may have significant real-life benefits for orientation, personal safety, and social interactions, thereby improving quality of life.
Collapse
Affiliation(s)
- Roksana Sadeghi
- Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Arathy Kartha
- Department of Ophthalmology, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | | | - Chris Bradley
- Department of Ophthalmology, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Paul Gibson
- Advanced Medical Electronics Corporation, Maple Grove, MN, USA
| | - Avi Caspi
- Second Sight Medical Products, Sylmar, CA, USA; Jerusalem College of Technology, Jerusalem, Israel
| | - Arup Roy
- Second Sight Medical Products, Sylmar, CA, USA
| | - Gislin Dagnelie
- Department of Ophthalmology, Johns Hopkins School of Medicine, Baltimore, MD, USA
| |
Collapse
|
8
|
Abstract
Visual prostheses aim to restore, at least to some extent, vision that leads to the type of perception available for sighted patients. Their effectiveness is almost always evaluated using clinical tests of vision. Clinical vision tests are designed to measure the limits of parameters of a functioning visual system. I argue here that these tests are rarely suited to determine the ability of prosthetic devices and other therapies to restore vision. This paper describes and explains many limitations of these evaluations. Prosthetic vision testing often makes use of multiple-alternative forced-choice (MAFC) procedures. Although these paradigms are suitable for many studies, they are frequently problematic in vision restoration evaluation. Two main types of problems are identified: (1) where nuisance variables provide spurious cues that can be learned in repeated training, which is common in prosthetic vision, and thus defeat the purpose of the test; and (2) even though a test is properly designed and performed, it may not actually measure what the researchers believe, and thus the interpretation of results is wrong. Examples for both types of problems are presented. Additional problems arise from confounding factors in the administration of tests are pointed as limitations of current device evaluation. For example, head tracing of magnified objects enlarged to compensate for the system's low resolution, in distinction from the scanning head (camera) movements with which users of prosthetic devices expand the limited field of view. Because of these problems, the ability to perform satisfactorily on the clinical tests is necessary but insufficient to prove vision restoration, therefore, additional tests are needed. I propose some directions to pursue in such testing. Translational Relevance Numerous prosthetic devices are being developed and introduced to the market. Proving the utility of these devices is crucial for regulatory and even for post market acceptance, which so far has largely failed, in my opinion. Potential reasons for the failures despite success in regulatory testing and directions for designing improved testing are provided. It is hoped that improved testing will guide improved designs of future prosthetic systems and other vision restoration approaches.
Collapse
Affiliation(s)
- Eli Peli
- Schepens Eye Research Institute of Mass Eye & Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA
| |
Collapse
|
9
|
Bareket L, Barriga-Rivera A, Zapf MP, Lovell NH, Suaning GJ. Progress in artificial vision through suprachoroidal retinal implants. J Neural Eng 2018; 14:045002. [PMID: 28541930 DOI: 10.1088/1741-2552/aa6cbb] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Retinal implants have proven their ability to restore visual sensation to people with degenerative retinopathy, characterized by photoreceptor cell death and the retina's inability to sense light. Retinal bionics operate by electrically stimulating the surviving neurons in the retina, thus triggering the transfer of visual sensory information to the brain. Suprachoroidal implants were first investigated in Australia in the 1950s. In this approach, the neuromodulation hardware is positioned between the sclera and the choroid, thus providing significant surgical and safety benefits for patients, with the potential to maintain residual vision combined with the artificial input from the device. Here we review the latest advances and state of the art devices for suprachoroidal prostheses, highlight future technologies and discuss challenges and perspectives towards improved rehabilitation of vision.
Collapse
Affiliation(s)
- Lilach Bareket
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia
| | | | | | | | | |
Collapse
|
10
|
Han S, Qiu C, Lee KR, Jung JH, Peli E. Word recognition: re-thinking prosthetic vision evaluation. J Neural Eng 2018; 15:055003. [PMID: 29781807 DOI: 10.1088/1741-2552/aac663] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
OBJECTIVE 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.
Collapse
Affiliation(s)
- Shui'Er Han
- Department of Ophthalmology, The Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, 20 Staniford Street, Boston, MA 02114-2500, United States of America. School of Psychology, University of Sydney, Sydney, Australia
| | | | | | | | | |
Collapse
|