Performance of real-world functional vision tasks by blind subjects improves after implantation with the Argus® II retinal prosthesis system.

BACKGROUND: The main objective of this study was to test Argus II subjects on three real-world functional vision tasks. DESIGN: The study was designed to be randomized and prospective. Testing was conducted in a hospital/research laboratory setting at the various participating centres. PARTICIPANTS: Twenty eight Argus II subjects, all profoundly blind, participated in this study. METHODS: Subjects were tested on the three real-world functional vision tasks: Sock Sorting, Sidewalk Tracking and Walking Direction Discrimination task MAIN OUTCOME MEASURES: For the Sock Sorting task, percentage correct was computed based on how accurately subjects sorted the piles on a cloth-covered table and on a bare table. In the Sidewalk Tracking task, an 'out of bounds' count was recorded, signifying how often the subject veered away from the test course. During the Walking Direction Discrimination task, subjects were tested on the number of times they correctly identified the direction of testers walking across their field of view. RESULTS: The mean percentage correct OFF versus ON for the Sock Sorting task was found to be significantly different for both testing conditions (t-test, P < 0.01). On the Sidewalk Tracking task, subjects performed significantly better with the system ON than they did with the system OFF (t-test, P < 0.05). Eighteen (18) of 27 subjects (67%) performed above chance with the system ON, and 6 (22%) did so with system OFF on the Walking Direction Discrimination task. CONCLUSIONS: Argus II subjects performed better on all three tasks with their systems ON than they did with their systems OFF.

Rethinking ADA signage standards for low-vision accessibility.

Americans With Disabilities Act (ADA) and International Code Council (ICC) standards for accessible buildings and facilities affect design and construction of all new and renovated buildings throughout the United States, and form the basis for compliance with the ADA. While these standards may result in acceptable accessibility for people who are fully blind, they fall far short of what they could and should accomplish for those with low vision. In this article I critique the standards, detailing their lack of evidence base and other shortcomings. I suggest that simply making existing requirements stricter (e.g., by mandating larger letter size or higher contrasts) will not ensure visual accessibility and therefore cannot act as a valid basis for compliance with the law. I propose two remedies. First, requirements for visual characteristics of signs intended to improve access for those with low vision should be expressed not in terms of physical features, such as character height and contrast, but rather in terms of the distance at which a sign can be read by someone with nominally normal (20/20) visual acuity under expected lighting conditions for the installed environment. This would give sign designers greater choice in design parameters but place on them the burden of ensuring legibility. Second, mounting of directional signs, which are critical for effective and efficient wayfinding, should be required to be in consistent and approachable locations so that those with reduced acuity may view them at close distance.

Five-Year Safety and Performance Results from the Argus II Retinal Prosthesis System Clinical Trial.

PURPOSE: The Argus II Retinal Prosthesis System (Second Sight Medical Products, Inc, Sylmar, CA) was developed to restore some vision to patients blind as a result of retinitis pigmentosa (RP) or outer retinal degeneration. A clinical trial was initiated in 2006 to study the long-term safety and efficacy of the Argus II System in patients with bare or no light perception resulting from end-stage RP. DESIGN: Prospective, multicenter, single-arm clinical trial. Within-patient controls included the nonimplanted fellow eye and patients' native residual vision compared with their vision with the Argus II. PARTICIPANTS: Thirty participants in 10 centers in the United States and Europe. METHODS: The worse-seeing eye of blind patients was implanted with the Argus II. Patients wore glasses mounted with a small camera and a video processor that converted images into stimulation patterns sent to the electrode array on the retina. MAIN OUTCOME MEASURES: The primary outcome measures were safety (the number, seriousness, and relatedness of adverse events) and visual function, as measured by 3 computer-based, objective tests. Secondary measures included functional vision performance on objectively scored real-world tasks. RESULTS: Twenty-four of 30 patients remained implanted with functioning Argus II Systems at 5 years after implantation. Only 1 additional serious adverse event was experienced after the 3-year time point. Patients performed significantly better with the Argus II on than off on all visual function tests and functional vision tasks. CONCLUSIONS: The 5-year results of the Argus II trial support the long-term safety profile and benefit of the Argus II System for patients blind as a result of RP. The Argus II is the first and only retinal implant to have market approval in the European Economic Area, the United States, and Canada.

Long-Term Results from an Epiretinal Prosthesis to Restore Sight to the Blind.

PURPOSE: Retinitis pigmentosa (RP) is a group of inherited retinal degenerations leading to blindness due to photoreceptor loss. Retinitis pigmentosa is a rare disease, affecting only approximately 100 000 people in the United States. There is no cure and no approved medical therapy to slow or reverse RP. The purpose of this clinical trial was to evaluate the safety, reliability, and benefit of the Argus II Retinal Prosthesis System (Second Sight Medical Products, Inc, Sylmar, CA) in restoring some visual function to subjects completely blind from RP. We report clinical trial results at 1 and 3 years after implantation. DESIGN: The study is a multicenter, single-arm, prospective clinical trial. PARTICIPANTS: There were 30 subjects in 10 centers in the United States and Europe. Subjects served as their own controls, that is, implanted eye versus fellow eye, and system on versus system off (native residual vision). METHODS: The Argus II System was implanted on and in a single eye (typically the worse-seeing eye) of blind subjects. Subjects wore glasses mounted with a small camera and a video processor that converted images into stimulation patterns sent to the electrode array on the retina. MAIN OUTCOME MEASURES: The primary outcome measures were safety (the number, seriousness, and relatedness of adverse events) and visual function, as measured by 3 computer-based, objective tests. RESULTS: A total of 29 of 30 subjects had functioning Argus II Systems implants 3 years after implantation. Eleven subjects experienced a total of 23 serious device- or surgery-related adverse events. All were treated with standard ophthalmic care. As a group, subjects performed significantly better with the system on than off on all visual function tests and functional vision assessments. CONCLUSIONS: The 3-year results of the Argus II trial support the long-term safety profile and benefit of the Argus II System for patients blind from RP. Earlier results from this trial were used to gain approval of the Argus II by the Food and Drug Administration and a CE mark in Europe. The Argus II System is the first and only retinal implant to have both approvals.

Interim results from the international trial of Second Sight's visual prosthesis.

PURPOSE: This study evaluated the Argus II Retinal Prosthesis System (Second Sight Medical Products, Inc., Sylmar, CA) in blind subjects with severe outer retinal degeneration. DESIGN: Single-arm, prospective, multicenter clinical trial. PARTICIPANTS: Thirty subjects were enrolled in the United States and Europe between June 6, 2007, and August 11, 2009. All subjects were followed up for a minimum of 6 months and up to 2.7 years. METHODS: The electronic stimulator and antenna of the implant were sutured onto the sclera using an encircling silicone band. Next, a pars plana vitrectomy was performed, and the electrode array and cable were introduced into the eye via a pars plana sclerotomy. The microelectrode array then was tacked to the epiretinal surface. MAIN OUTCOME MEASURES: The primary safety end points for the trial were the number, severity, and relation of adverse events. Principal performance end points were assessments of visual function as well as performance on orientation and mobility tasks. RESULTS: Subjects performed statistically better with the system on versus off in the following tasks: object localization (96% of subjects), motion discrimination (57%), and discrimination of oriented gratings (23%). The best recorded visual acuity to date is 20/1260. Subjects' mean performance on orientation and mobility tasks was significantly better when the system was on versus off. Seventy percent of the patients did not have any serious adverse events (SAEs). The most common SAE reported was either conjunctival erosion or dehiscence over the extraocular implant and was treated successfully in all subjects except in one, who required explantation of the device without further complications. CONCLUSIONS: The long-term safety results of Second Sight's retinal prosthesis system are acceptable, and most subjects with profound visual loss perform better on visual tasks with system than without it.

Clothing Matching for Visually Impaired Persons.

Matching clothes is a challenging task for many blind people. In this paper, we present a proof of concept system to solve this problem. The system consists of 1) a camera connected to a computer to perform pattern and color matching process; 2) speech commands for system control and configuration; and 3) audio feedback to provide matching results for both color and patterns of clothes. This system can handle clothes in deficient color without any pattern, as well as clothing with multiple colors and complex patterns to aid both blind and color deficient people. Furthermore, our method is robust to variations of illumination, clothing rotation and wrinkling. To evaluate the proposed prototype, we collect two challenging databases including clothes without any pattern, or with multiple colors and different patterns under different conditions of lighting and rotation. Results reported here demonstrate the robustness and effectiveness of the proposed clothing matching system.

Reduced visual acuity is mirrored in low vision imagery.

Research has examined the nature of visual imagery in normally sighted and blind subjects, but not in those with low vision. Findings with normally sighted subjects suggest that imagery involves primary visual areas of the brain. Since the plasticity of visual cortex appears to be limited in adulthood, we might expect imagery of those with adult-onset low vision to be relatively unaffected by these losses. But if visual imagery is based on recent and current experience, we would expect images of those with low vision to share some properties of impaired visual perception. We examined key parameters of mental images reported by normally sighted subjects, compared to those with early- and late-onset low vision, and with a group of subjects with restricted visual fields using an imagery questionnaire. We found evidence that those with reduced visual acuity report the imagery distances of objects to be closer than those with normal acuity and also depict objects in imagery with lower resolution than those with normal visual acuity. We also found that all low vision groups, like the normally sighted, image objects at a substantially greater distance than when asked to place them at a distance that 'just fits' their imagery field (overflow distance). All low vision groups, like the normally sighted, showed evidence of a limited visual field for imagery, but our group with restricted visual fields did not differ from the other groups in this respect. We conclude that imagery of those with low vision is similar to that of those with normal vision in being dependent on the size of objects or features being imaged, but that it also reflects their reduced visual acuity. We found no evidence for a dependence on imagery of age of onset or number of years of vision impairment.

Vision-based Mobile Indoor Assistive Navigation Aid for Blind People.

This paper presents a new holistic vision-based mobile assistive navigation system to help blind and visually impaired people with indoor independent travel. The system detects dynamic obstacles and adjusts path planning in real-time to improve navigation safety. First, we develop an indoor map editor to parse geometric information from architectural models and generate a semantic map consisting of a global 2D traversable grid map layer and context-aware layers. By leveraging the visual positioning service (VPS) within the Google Tango device, we design a map alignment algorithm to bridge the visual area description file (ADF) and semantic map to achieve semantic localization. Using the on-board RGB-D camera, we develop an efficient obstacle detection and avoidance approach based on a time-stamped map Kalman filter (TSM-KF) algorithm. A multi-modal human-machine interface (HMI) is designed with speech-audio interaction and robust haptic interaction through an electronic SmartCane. Finally, field experiments by blindfolded and blind subjects demonstrate that the proposed system provides an effective tool to help blind individuals with indoor navigation and wayfinding.

Letter case and text legibility in normal and low vision.

It is thought by cognitive scientists and typographers alike, that lower-case text is more legible than upper-case. Yet lower-case letters are, on average, smaller in height and width than upper-case characters, which suggests an upper-case advantage. Using a single unaltered font and all upper-, all lower-, and mixed-case text, we assessed size thresholds for words and random strings, and reading speeds for text with normal and visually impaired participants. Lower-case thresholds were roughly 0.1 log unit higher than upper. Reading speeds were higher for upper- than for mixed-case text at sizes twice acuity size; at larger sizes, the upper-case advantage disappeared. Results suggest that upper-case is more legible than the other case styles, especially for visually-impaired readers, because smaller letter sizes can be used than with the other case styles, with no diminution of legibility.

Improvements in vision-related quality of life in blind patients implanted with the Argus II Epiretinal Prosthesis.

BACKGROUND: The purpose of this analysis is to report the change in quality of life (QoL) after treatment with the Argus II Epiretinal Prosthesis in patients with end-stage retinitis pigmentosa. METHODS: The Vision and Quality of Life Index (VisQoL) was used to assess changes in QoL dimensions and overall utility score in a prospective 30-patient single-arm clinical study. VisQoL is a multi-attribute instrument consisting of six dimensions (injury, life, roles, assistance, activity and friendship) that may be affected by visual impairment. Within each dimension, patients were divided into two groups based on how much their QoL was affected by their blindness at baseline (moderate/severe or minimal). Outcomes were compared within each dimension sub-group between baseline and the combined follow-up periods using the Friedman test. In addition, data from the six dimensions were combined into a single utility score, with baseline data compared to the combined follow-up periods. RESULTS: Overall, 80 per cent of the patients reported difficulty in one or more dimensions pre-implant. Composite VisQoL utility scores at follow-up showed no statistically significant change from baseline; however, in three of the six VisQoL dimensions (injury, life and roles), patients with baseline deficits showed significant and lasting improvement after implantation with Argus II. In two of the three remaining dimensions (assistance and activity), data trended toward an improvement. In the final VisQoL dimension (friendship), none of the patients reported baseline deficits, suggesting that patients had largely adjusted to this attribute. CONCLUSION: Patients whose vision negatively affected them with respect to three VisQoL dimensions (that is, getting injured, coping with the demands of their life and fulfilling their life roles) reported significant improvement in QoL after implantation of the Argus II retinal prosthesis. Furthermore, the benefit did not deteriorate at any point during the 36-month follow-up, suggesting a long-term, durable improvement.

Lapse resistance in the verbal letter reporting task.

Lapses, or misreporting errors, can affect accuracy of threshold measurements. Assumptions about lapse rate, especially in untrained observers, have consequently guided the design of at least one clinical psychophysical test. Lapse rate was assessed using a verbal letter identification paradigm like that used in visual acuity and letter contrast sensitivity testing. Subjects occasionally made slip-of-the tongue errors but spontaneously corrected them. Lapse rate (excluding such errors) was 0-3 errors per 1,536 (average rate of 0.0005). In this common clinical paradigm, in which observers set their reporting pace, and where opportunity to amend responses is available, lapse rate is negligible.

An analysis of observer-rated functional vision in patients implanted with the Argus II Retinal Prosthesis System at three years.

OBJECTIVE: The purpose of this analysis was to compare observer-rated tasks in patients implanted with the Argus II Retinal Prosthesis System, when the device is ON versus OFF. METHODS: The Functional Low-Vision Observer Rated Assessment (FLORA) instrument was administered to 26 blind patients implanted with the Argus II Retinal Prosthesis System at a mean follow-up of 36 months. FLORA is a multi-component instrument that consists in part of observer-rated assessment of 35 tasks completed with the device ON versus OFF. The ease with which a patient completes a task is scored using a four-point scale, ranging from easy (score of 1) to impossible (score of 4). The tasks are evaluated individually and organised into four discrete domains, including 'Visual orientation', 'Visual mobility', 'Daily life and 'Interaction with others'. RESULTS: Twenty-six patients completed each of the 35 tasks. Overall, 24 out of 35 tasks (69 per cent) were statistically significantly easier to achieve with the device ON versus OFF. In each of the four domains, patients' performances were significantly better (p < 0.05) with the device ON versus OFF, ranging from 19 to 38 per cent improvement. CONCLUSION: Patients with an Argus II Retinal Prosthesis implanted for 18 to 44 months (mean 36 months), demonstrated significantly improved completion of vision-related tasks with the device ON versus OFF.

Improving the design of the letter contrast sensitivity test.

PURPOSE: To develop a small-format letter contrast sensitivity test with improved accuracy, suitable for portable use and near testing, and having a simple and unambiguous scoring system that can be used with reference to existing norms. METHODS: A near test, printed on resin-coated paper and mounted on plastic was developed by using Sloan letters, with 0.04 log unit contrast decrements between each letter and a simple scoring procedure. Monte Carlo methods and a Weibull function model of visual performance were used to assess test accuracy. RESULTS: The new test has 28% lower score standard deviations than the Pelli-Robson Contrast Sensitivity Chart, over a wide range of low misreporting rates, while maintaining test scores that differ from the Pelli-Robson by 0.01 log unit, permitting use of norms collected with the Pelli-Robson test. CONCLUSIONS: While maintaining comparability with Pelli-Robson norms, the new test has improved accuracy in comparison with the Pelli-Robson chart and several other advantages that result from its smaller size.

Serifs and font legibility.

Using lower-case fonts varying only in serif size (0%, 5%, and 10% cap height), we assessed legibility using size thresholds and reading speed. Five percentage serif fonts were slightly more legible than sans serif, but the average inter-letter spacing increase that serifs themselves impose, predicts greater enhancement than we observed. RSVP and continuous reading speeds showed no effect of serifs. When text is small or distant, serifs may, then, produce a tiny legibility increase due to the concomitant increase in spacing. However, our data exhibited no difference in legibility between typefaces that differ only in the presence or absence of serifs.

Toward a Computer Vision-based Wayfinding Aid for Blind Persons to Access Unfamiliar Indoor Environments.

Independent travel is a well known challenge for blind and visually impaired persons. In this paper, we propose a proof-of-concept computer vision-based wayfinding aid for blind people to independently access unfamiliar indoor environments. In order to find different rooms (e.g. an office, a lab, or a bathroom) and other building amenities (e.g. an exit or an elevator), we incorporate object detection with text recognition. First we develop a robust and efficient algorithm to detect doors, elevators, and cabinets based on their general geometric shape, by combining edges and corners. The algorithm is general enough to handle large intra-class variations of objects with different appearances among different indoor environments, as well as small inter-class differences between different objects such as doors and door-like cabinets. Next, in order to distinguish intra-class objects (e.g. an office door from a bathroom door), we extract and recognize text information associated with the detected objects. For text recognition, we first extract text regions from signs with multiple colors and possibly complex backgrounds, and then apply character localization and topological analysis to filter out background interference. The extracted text is recognized using off-the-shelf optical character recognition (OCR) software products. The object type, orientation, location, and text information are presented to the blind traveler as speech.

Adjustable typography: an approach to enhancing low vision text accessibility.

Millions of people have low vision, a disability condition caused by uncorrectable or partially correctable disorders of the eye. The primary goal of low vision rehabilitation is increasing access to printed material. This paper describes how adjustable typography, a computer graphic approach to enhancing text accessibility, can play a role in this process, by allowing visually-impaired users to customize fonts to maximize legibility according to their own visual needs. Prototype software and initial testing of the concept is described. The results show that visually-impaired users tend to produce a variety of very distinct fonts, and that the adjustment process results in greatly enhanced legibility. But this initial testing has not yet demonstrated increases in legibility over and above the legibility of highly legible standard fonts such as Times New Roman.