The number of patients with low vision is increasing as life expectancy increases. In addition, the interest and demand for low vision aids are also increasing with improved socioeconomic status and the development of mass media. Therefore, it is imperative to recognize the importance of low vision aids. We reviewed the clinical records of 118 patients who visited our low vision clinic more than twice. According to the data analyzed, optic nerve atrophy, retinal degeneration, diabetic retinopathy and age-related macular degeneration were the most common causes of low vision in these patients. The best corrected visual acuities without low vision aids were less than 0.3, but with the help of low vision aids, vision improved to more than 0.4 in 87% of the patients for near vision, and 56% for distant vision. The patients had complained that they could not read books, see a blackboard, recognize a person at a distance, and had other problems because of low vision. However, with the use of low vision aids their satisfaction with their vision rose to 70%. Hand magnifiers, high-powered spectacle lenses, and stand magnifiers were the low vision aids commonly used by people for near vision, while the Galilean telescope and Keplerian telescope were the most popular devices used for distant vision. In conclusion, low vision aids are very helpful devices to patients with low vision. (+info)
Adaptive changes in early and late blind: a fMRI study of Braille reading.
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Braille reading depends on remarkable adaptations that connect the somatosensory system to language. We hypothesized that the pattern of cortical activations in blind individuals reading Braille would reflect these adaptations. Activations in visual (occipital-temporal), frontal-language, and somatosensory cortex in blind individuals reading Braille were examined for evidence of differences relative to previously reported studies of sighted subjects reading print or receiving tactile stimulation. Nine congenitally blind and seven late-onset blind subjects were studied with fMRI as they covertly performed verb generation in response to reading Braille embossed nouns. The control task was reading the nonlexical Braille string "######". This study emphasized image analysis in individual subjects rather than pooled data. Group differences were examined by comparing magnitudes and spatial extent of activated regions first determined to be significant using the general linear model. The major adaptive change was robust activation of visual cortex despite the complete absence of vision in all subjects. This included foci in peri-calcarine, lingual, cuneus and fusiform cortex, and in the lateral and superior occipital gyri encompassing primary (V1), secondary (V2), and higher tier (VP, V4v, LO and possibly V3A) visual areas previously identified in sighted subjects. Subjects who never had vision differed from late blind subjects in showing even greater activity in occipital-temporal cortex, provisionally corresponding to V5/MT and V8. In addition, the early blind had stronger activation of occipital cortex located contralateral to the hand used for reading Braille. Responses in frontal and parietal cortex were nearly identical in both subject groups. There was no evidence of modifications in frontal cortex language areas (inferior frontal gyrus and dorsolateral prefrontal cortex). Surprisingly, there was also no evidence of an adaptive expansion of the somatosensory or primary motor cortex dedicated to the Braille reading finger(s). Lack of evidence for an expected enlargement of the somatosensory representation may have resulted from balanced tactile stimulation and gross motor demands during Braille reading of nouns and the control fields. Extensive engagement of visual cortex without vision is discussed in reference to the special demands of Braille reading. It is argued that these responses may represent critical language processing mechanisms normally present in visual cortex. (+info)
Facial recognition using simulated prosthetic pixelized vision.
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PURPOSE: To evaluate a model of simulated pixelized prosthetic vision using noncontiguous circular phosphenes, to test the effects of phosphene and grid parameters on facial recognition. METHODS: A video headset was used to view a reference set of four faces, followed by a partially averted image of one of those faces viewed through a square pixelizing grid that contained 10x10 to 32x32 dots separated by gaps. The grid size, dot size, gap width, dot dropout rate, and gray-scale resolution were varied separately about a standard test condition, for a total of 16 conditions. All tests were first performed at 99% contrast and then repeated at 12.5% contrast. RESULTS: Discrimination speed and performance were influenced by all stimulus parameters. The subjects achieved highly significant facial recognition accuracy for all high-contrast tests except for grids with 70% random dot dropout and two gray levels. In low-contrast tests, significant facial recognition accuracy was achieved for all but the most adverse grid parameters: total grid area less than 17% of the target image, 70% dropout, four or fewer gray levels, and a gap of 40.5 arcmin. For difficult test conditions, a pronounced learning effect was noticed during high-contrast trials, and a more subtle practice effect on timing was evident during subsequent low-contrast trials. CONCLUSIONS: These findings suggest that reliable face recognition with crude pixelized grids can be learned and may be possible, even with a crude visual prosthesis. (+info)
Improved mobility and independence of night-blind people using night-vision goggles.
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PURPOSE: To investigate whether the use of night-vision goggles (NVGs) by night-blind people improves their mobility and sense of independence under dark circumstances. METHODS: Twenty night-blind subjects with retinitis pigmentosa were requested to walk predetermined routes at night with and without NVGs. The number of unintended contacts with obstacles (hits) and the percentage of preferred walking speed (PPWS) en route were assessed in three different situations: a darkened indoor corridor; a moderately lit outdoor residential area; and a well-lit outdoor shopping area. Assessments were performed before and after a 5-week training period, during which the subjects practiced using NVGs in their own surroundings, registered their experiences in a journal, and filled out questionnaires. RESULTS: The mean number of hits in the darkened corridor declined from eight to two when NVGs were used. Mean PPWS (34%) did not improve. In the residential area, mean hits declined from eight to practically zero and mean PPWS increased from 60% to 72% (after training to 78%). In the shopping area, subjects walked at 93% PPWS without any hits and showed no improvement with NVGs. Subjective scores revealed a good sense of orientation, feelings of safety and tranquility and an increase in independent mobility when NVGs were used. CONCLUSIONS: Using NVGs seems to improve nighttime mobility in dark outdoor conditions by decreasing unintended contacts with obstacles and increasing walking speed. Use of NVGs increased independent activities in these subjects and was generally positively evaluated for everyday outdoor use. (+info)
Enhanced low vision rehabilitation for people with age related macular degeneration: a randomised controlled trial.
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AIM: To compare the effectiveness of three models of low vision rehabilitation for people with age related macular degeneration (AMD) referred for low vision rehabilitation (LVR): (a) an enhanced low vision rehabilitation model (ELVR) including supplementary home based low vision rehabilitation; (b) conventional low vision rehabilitation (CLVR) based in a hospital clinic; (c) CLVR with home visits that did not include rehabilitation (CELVR), intended to act as a control for the additional contact time with ELVR. METHOD: A single centre parallel group randomised controlled trial in participants' homes and the low vision clinic, Manchester Royal Eye Hospital. People referred for LVR with a primary diagnosis of AMD and visual acuity worse than 6/18 in both eyes and equal to or better than 1/60 in the better eye. The main outcome measures were vision specific quality of life (QoL) (primary outcome, VCM1) and generic health related QoL (SF-36); psychological adjustment to vision loss; measured task performance; restriction in everyday activities; use of low vision aids (LVAs). RESULTS: 226 participants were recruited (median age 82 years); 194 completed the trial (86%). Except for SF-36 physical and mental component summary scores, arms did not differ significantly for any of the outcomes. Differences for the VCM1 were ELVR v CLVR, 0.06 (95% CI to 0.17 to 0.30, p = 0.60); ELVR v CELVR, 0.12 (95% CI to 0.11 to 0.34, p = 0.31); CELVR v CLVR, -0.05 (95% CI -0.29 to 0.18, p = 0.64). Differences for the SF-36 favoured CLVR compared to ELVR (ELVR v CLVR: physical = -6.05, 95% CI -10.2 to -1.91, p = 0.004; mental = -4.04, 95% CI -7.44 to -0.65, p = 0.02). At 12 months, 94% of participants reported using at least one LVA. CONCLUSION: ELVR was no more effective than CLVR. Researchers should be wary of proposing new LVR interventions without preliminary evidence of effectiveness, given the manifest lack of effectiveness of the model of enhanced LVR evaluated in the trial. (+info)
Computerized microfluidic cell culture using elastomeric channels and Braille displays.
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Computer-controlled microfluidics would advance many types of cellular assays and microscale tissue engineering studies wherever spatiotemporal changes in fluidics need to be defined. However, this goal has been elusive because of the limited availability of integrated, programmable pumps and valves. This paper demonstrates how a refreshable Braille display, with its grid of 320 vertically moving pins, can power integrated pumps and valves through localized deformations of channel networks within elastic silicone rubber. The resulting computerized fluidic control is able to switch among: (i) rapid and efficient mixing between streams, (ii) multiple laminar flows with minimal mixing between streams, and (iii) segmented plug-flow of immiscible fluids within the same channel architecture. The same control method is used to precisely seed cells, compartmentalize them into distinct subpopulations through channel reconfiguration, and culture each cell subpopulation for up to 3 weeks under perfusion. These reliable microscale cell cultures showed gradients of cellular behavior from C2C12 myoblasts along channel lengths, as well as differences in cell density of undifferentiated myoblasts and differentiation patterns, both programmable through different flow rates of serum-containing media. This technology will allow future microscale tissue or cell studies to be more accessible, especially for high-throughput, complex, and long-term experiments. The microfluidic actuation method described is versatile and computer programmable, yet simple, well packaged, and portable enough for personal use. (+info)
Design specifications of audio-guidance systems for the blind in public spaces.
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The government of Fukuoka City conducted a survey to determine the effectiveness of an audio-guidance system for the blind. The blind participants confirmed the usefulness of the audio-guidance. In addition, the blind participants and the walking instructors also provided various comments and suggestions for the better utilization of audio-guidance systems for smoother transportation. In order for the participants to be able to recognize auditory signals, it was important to be able to hear them at their peak volumes. To understand the actual meaning of announcements, however, the average volumes of the signals were more important than their peak volumes. The blind participants suggested that auditory signals and announcements should provide short and simple messages. The walking instructors provided comments regarding the placement of loudspeakers to enhance auditory localization. They recommended hanging the loudspeakers from ceilings located in front of passengers. Furthermore, the necessity of controlling excess reverberations was indicated in order to better enable blind citizens to recognize and localize the auditory signals. It was suggested that using different auditory signals for different purposes and places was effective for smoother transportation. (+info)
Bioptic telescopes meet the needs of drivers with moderate visual acuity loss.
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PURPOSE: Visually impaired people are permitted to use bioptic telescopes for driving in many states in the United States. However, it has been suggested that the telescope is used only to meet the visual acuity criteria for licensure. In this study, a survey was used to establish the extent to which bioptic telescopes are used by and meet the driving needs of people with moderately reduced visual acuity. METHODS: A cross-sectional survey of a convenience sample of 58 bioptic drivers was administered by telephone interview. Bioptic telescope usage patterns were quantified with questions designed specifically for the study. Driving patterns were quantified by use of the Driving Habits Questionnaire. Subjects were recruited from four sources across the United States to ensure a range of bioptic training and driving experience. RESULTS: The majority (74%) rated the bioptic telescope as very helpful, and almost all (90%) would continue to use it for driving, even if it were not required for driving licensure; however, only 62% reported always wearing the bioptic when driving. Subjects had relatively unrestricted driving habits, driving a mean of 222 +/- 211 miles per week, and 85% aged < or =65 years drove to work. With the exception of driving in rain, in bright sunlight, and at night, there was little difficulty with driving in a variety of situations, and levels of driving avoidance due to vision impairment were low (<10%). CONCLUSIONS: The bioptic telescope met the (self-reported) driving needs of the majority of visually impaired drivers in this survey and was found to be a useful aid for tasks requiring resolution of detail. (+info)