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.
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.
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.
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.
This study evaluated the Argus II Retinal Prosthesis System (Second Sight Medical Products, Inc., Sylmar, CA) in blind subjects with severe outer retinal degeneration.
Single-arm, prospective, ...multicenter clinical trial.
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.
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.
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.
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.
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.
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.
The study is a multicenter, single-arm, prospective clinical trial.
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).
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.
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.
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.
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.
We propose a camera-based assistive text reading framework to help blind persons read text labels and product packaging from hand-held objects in their daily lives. To isolate the object from ...cluttered backgrounds or other surrounding objects in the camera view, we first propose an efficient and effective motion-based method to define a region of interest (ROI) in the video by asking the user to shake the object. This method extracts moving object region by a mixture-of-Gaussians-based background subtraction method. In the extracted ROI, text localization and recognition are conducted to acquire text information. To automatically localize the text regions from the object ROI, we propose a novel text localization algorithm by learning gradient features of stroke orientations and distributions of edge pixels in an Adaboost model. Text characters in the localized text regions are then binarized and recognized by off-the-shelf optical character recognition software. The recognized text codes are output to blind users in speech. Performance of the proposed text localization algorithm is quantitatively evaluated on ICDAR-2003 and ICDAR-2011 Robust Reading Datasets. Experimental results demonstrate that our algorithm achieves the state of the arts. The proof-of-concept prototype is also evaluated on a dataset collected using ten blind persons to evaluate the effectiveness of the system's hardware. We explore user interface issues and assess robustness of the algorithm in extracting and reading text from different objects with complex backgrounds.
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.
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.
Thirty participants in 10 centers in the United States and Europe.
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.
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.
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.
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.
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 laboratory, 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, 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 software products. The object type, orientation, location, and text information are presented to the blind traveler as speech.
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.
Introduction
Development of a sensing device that can provide a sufficient perceptual substrate for persons with visual impairments to orient themselves and travel confidently has been a persistent ...rehabilitation technology goal, with the user interface posing a significant challenge. In the study presented here, we enlist the advice and ideas of individuals who are blind with respect to this challenge, for an envisioned camera-based aid to navigation and wayfinding.
Methods
We administered a short questionnaire about user preferences and needs for such a device to a sample of 10 well-educated, employed (or retired) visually impaired participants with light perception or less, who were familiar and comfortable with assistive technology. Generally, the items were rankings of relative priority.
Results
Participants preferred speech as a communications medium for navigating the environment; preferred controlling the auditory display by querying the system rather than interacting via a menu or receiving a stream of continuous speech; and preferred providing input to the system through a keypad rather than through a voice recognition system. Architectural features such as doors and stairs were ranked the most important environmental objects to be located with such a device (over furniture, persons, personal items, and even text signs).
Discussion
Our sample reported a desire for devices that can guide them to architectural features of their environment. They appear to prefer device interfaces that give them control, and would rather query a system than interact with a menu. They prefer unobtrusive input on a device via keypad rather than through voice recognition.
Implications for practitioners
Designers of camera-based navigation devices may wish to consider the preferences of our sample by incorporating a query-based interface with simple keypad input and speech output, and to include in their object recognition efforts the goal of identifying architectural features that are significant to users who are blind in navigation.
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.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK, VSZLJ
Many causes of vision impairment can be prevented or treated. With an ageing global population, the demands for eye health services are increasing. We estimated the prevalence and relative ...contribution of avoidable causes of blindness and vision impairment globally from 1990 to 2020. We aimed to compare the results with the World Health Assembly Global Action Plan (WHA GAP) target of a 25% global reduction from 2010 to 2019 in avoidable vision impairment, defined as cataract and undercorrected refractive error.
We did a systematic review and meta-analysis of population-based surveys of eye disease from January, 1980, to October, 2018. We fitted hierarchical models to estimate prevalence (with 95% uncertainty intervals UIs) of moderate and severe vision impairment (MSVI; presenting visual acuity from <6/18 to 3/60) and blindness (<3/60 or less than 10° visual field around central fixation) by cause, age, region, and year. Because of data sparsity at younger ages, our analysis focused on adults aged 50 years and older.
Global crude prevalence of avoidable vision impairment and blindness in adults aged 50 years and older did not change between 2010 and 2019 (percentage change −0·2% 95% UI −1·5 to 1·0; 2019 prevalence 9·58 cases per 1000 people 95% IU 8·51 to 10·8, 2010 prevalence 96·0 cases per 1000 people 86·0 to 107·0). Age-standardised prevalence of avoidable blindness decreased by −15·4% –16·8 to −14·3, while avoidable MSVI showed no change (0·5% –0·8 to 1·6). However, the number of cases increased for both avoidable blindness (10·8% 8·9 to 12·4) and MSVI (31·5% 30·0 to 33·1). The leading global causes of blindness in those aged 50 years and older in 2020 were cataract (15·2 million cases 9% IU 12·7–18·0), followed by glaucoma (3·6 million cases 2·8–4·4), undercorrected refractive error (2·3 million cases 1·8–2·8), age-related macular degeneration (1·8 million cases 1·3–2·4), and diabetic retinopathy (0·86 million cases 0·59–1·23). Leading causes of MSVI were undercorrected refractive error (86·1 million cases 74·2–101·0) and cataract (78·8 million cases 67·2–91·4).
Results suggest eye care services contributed to the observed reduction of age-standardised rates of avoidable blindness but not of MSVI, and that the target in an ageing global population was not reached.
Brien Holden Vision Institute, Fondation Théa, The Fred Hollows Foundation, Bill & Melinda Gates Foundation, Lions Clubs International Foundation, Sightsavers International, and University of Heidelberg.
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