Assessing optimal colour and illumination to facilitate reading.

PURPOSE: This study examined the effectiveness of the LuxIQ, the Apple iPad and a smart bulb in assessing optimal colour and illumination to facilitate reading in younger, older and visually impaired adults. METHODS: Participants read standardised texts at baseline (normal lighting/no device), then using the Apple iPad, LuxIQ and smart bulb, with their normal vision (20/20 condition) and using a simulated reduction in visual acuity/contrast sensitivity (20/80 condition). Visually impaired participants followed the same procedure used in the 20/80 condition. RESULTS: There was a significant interaction between condition and device in younger, F(1.5, 43.51) = 30.41, p < 0.001, ω2  = 0.34 and older, F(1.5, 4.51) = 4.51, p = 0.03, ω2  = 0.05 adults with normal vision, and there was a significant effect of device, F(2, 58) = 5.95, p = 0.004, ω2  = 0.12 in visually impaired adults. In the 20/20 condition, age and colour predicted reading speed, F(3, 176) = 36.25, p < 0.001, Adj. R2  = 0.37, whereas age, lighting and colour predicted reading speed, F(3, 176) = 36.25, p < 0.001, Adj. R2  = 0.37 in the 20/80 condition. In the visual impairment condition, lighting, colour and impairment severity predicted reading speed, F(3, 85) = 10.10, p < 0.001, Adj. R2  = 0.24. CONCLUSIONS: The clinical implications of this study are that reading speeds improve in individuals with low vision under improved lighting conditions, specifically, with higher levels of luminance and colour temperature. The effectiveness of the devices varied across groups; however, the LuxIQ was the only device to improve reading speeds from baseline in older adults with visual impairments.

Nonhuman primate vestibuloocular reflex responses to prosthetic vestibular stimulation are robust to pulse timing errors caused by temporal discretization.

Electrical stimulation of vestibular afferent neurons to partially restore semicircular canal sensation of head rotation and the stabilizing reflexes that sensation supports has potential to effectively treat individuals disabled by bilateral vestibular hypofunction. Ideally, a vestibular implant system using this approach would be integrated with a cochlear implant, which would provide clinicians with a means to simultaneously treat loss of both vestibular and auditory sensation. Despite obvious similarities, merging these technologies poses several challenges, including stimulus pulse timing errors that arise when a system must implement a pulse frequency modulation-encoding scheme (as is used in vestibular implants to mimic normal vestibular nerve encoding of head movement) within fixed-rate continuous interleaved sampling (CIS) strategies used in cochlear implants. Pulse timing errors caused by temporal discretization inherent to CIS create stair step discontinuities of the vestibular implant's smooth mapping of head velocity to stimulus pulse frequency. In this study, we assayed electrically evoked vestibuloocular reflex responses in two rhesus macaques using both a smooth pulse frequency modulation map and a discretized map corrupted by temporal errors typical of those arising in a combined cochlear-vestibular implant. Responses were measured using three-dimensional scleral coil oculography for prosthetic electrical stimuli representing sinusoidal head velocity waveforms that varied over 50-400°/s and 0.1-5 Hz. Pulse timing errors produced negligible effects on responses across all canals in both animals, indicating that temporal discretization inherent to implementing a pulse frequency modulation-coding scheme within a cochlear implant's CIS fixed pulse timing framework need not sacrifice performance of the combined system's vestibular implant portion. NEW & NOTEWORTHY Merging a vestibular implant system with existing cochlear implant technology can provide clinicians with a means to restore both vestibular and auditory sensation. Pulse timing errors inherent to integration of pulse frequency modulation vestibular stimulation with fixed-rate, continuous interleaved sampling cochlear implant stimulation would discretize the smooth head velocity encoding of a combined device. In this study, we show these pulse timing errors produce negligible effects on electrically evoked vestibulo-ocular reflex responses in two rhesus macaques.

Single-case synthesis tools II: Comparing quantitative outcome measures.

Varying methods for evaluating the outcomes of single case research designs (SCD) are currently used in reviews and meta-analyses of interventions. Quantitative effect size measures are often presented alongside visual analysis conclusions. Six measures across two classes-overlap measures (percentage non-overlapping data, improvement rate difference, and Tau) and parametric within-case effect sizes (standardized mean difference and log response ratio [increasing and decreasing])-were compared to determine if choice of synthesis method within and across classes impacts conclusions regarding effectiveness. The effectiveness of sensory-based interventions (SBI), a commonly used class of treatments for young children, was evaluated. Separately from evaluations of rigor and quality, authors evaluated behavior change between baseline and SBI conditions. SBI were unlikely to result in positive behavior change across all measures except IRD. However, subgroup analyses resulted in variable conclusions, indicating that the choice of measures for SCD meta-analyses can impact conclusions. Suggestions for using the log response ratio in SCD meta-analyses and considerations for understanding variability in SCD meta-analysis conclusions are discussed.

Single-case synthesis tools I: Comparing tools to evaluate SCD quality and rigor.

Tools for evaluating the quality and rigor of single case research designs (SCD) are often used when conducting SCD syntheses. Preferred components include evaluations of design features related to the internal validity of SCD to obtain quality and/or rigor ratings. Three tools for evaluating the quality and rigor of SCD (Council for Exceptional Children, What Works Clearinghouse, and Single-Case Analysis and Design Framework) were compared to determine if conclusions regarding the effectiveness of antecedent sensory-based interventions for young children changed based on choice of quality evaluation tool. Evaluation of SCD quality differed across tools, suggesting selection of quality evaluation tools impacts evaluation findings. Suggestions for selecting an appropriate quality and rigor assessment tool are provided and across-tool conclusions are drawn regarding the quality and rigor of studies. Finally, authors provide guidance for using quality evaluations in conjunction with outcome analyses when conducting syntheses of interventions evaluated in the context of SCD.

Hearing the way: requirements and preferences for technology-supported navigation aids.

Many systems have been developed to assist wayfinding for people with sight problems. There is a need for user requirements for such systems to be defined. This paper presents a study which aimed to determine such user requirements. An experiment was also conducted to establish the best way of guiding users between locations. The focus group results indicated that users require systems to provide them with information about their surroundings, to guide them along their route and to provide progress information. They also showed that users with sight conditions interact with systems differently to sighted users, thereby highlighting the importance of designing systems for the needs of these users. Results of the experiment found that the preferred method of guiding users was a notification when they were both on and off track. However, performance was best when only provided with the off track notification, implying that this cue is particularly important. Technology has the potential to support navigation for people with sight problems. Users should have control over cues provided and for these cues should supplement environmental cues rather than replacing them.

Guidelines for predicting performance with low vision AIDS.

PURPOSE: To determine predictors of success in reading with low vision aids, in terms of reading acuity, optimum acuity reserve, and maximum reading speed, for observers with vision loss from various causes. METHODS: One hundred people with vision loss affecting their daily lives participated. Clinical visual function measurements of distance acuity, contrast sensitivity, binocular threshold visual fields, and near reading performance with a MNRead chart at 40 cm were obtained. Reading performance aided by habitual low vision aids was also assessed with a MNRead chart. RESULTS: Aided reading acuity was best predicted by clinical reading acuity and contrast sensitivity. For most observers, a 2:1 acuity reserve was sufficient to achieve near-maximum reading speed, but one-third of observers with aided reading acuity better than 1.2 M required a higher acuity reserve. Aided maximum reading speed was best predicted by clinically assessed reading speed and by clinical reading acuity. CONCLUSIONS: People with vision impairment are likely to achieve 1 M with a low vision aid if their clinically assessed reading acuity is better than 0.85 logMAR. If acuity is worse than this, but contrast sensitivity is better than 1.05 logCS, 1M is also likely to be achieved. A 2:1 acuity reserve is adequate for 75% of observers, but those with good aided reading acuity may require further magnification to achieve best reading speeds. Fluent reading (>80 words per minute) is likely to be achieved if an observer reads fluently with large print at a fixed working distance and if clinically assessed reading acuity is better than 1.0 logMAR.

A versatile optoelectronic aid for low vision patients.

The purpose of this work is to describe a versatile optoelectronic aid for low vision rehabilitation based on reconfigurable hardware. This aid is easily adaptable to diverse pathologies (with different associated processing tasks) and to the progression of the visual impairment. This platform has a mobile configuration that uses a see-through head-mounted display (Nomad). We have implemented different types of vision enhancement on this versatile platform, and briefly summarize here their computational costs (in terms of hardware resource requirements). We have evaluated two representative capabilities of this aid (Augmented View and digital zoom) with measurements of visual acuity, contrast sensitivity and visual field. We have tested the Nomad head-mounted display and the Augmented View modality, in eight subjects with retinitis pigmentosa: the digital zoom was tested in six low vision subjects and nine normally-sighted subjects. We show that the Nomad display with Augmented View configuration does not impair the residual vision; and that there is an increase in visual acuity (VA) with the digital zoom configuration. The major advantage of this platform is that it can easily embed different image processing tasks and since it is based on a FPGA device, it can be specifically configured to tasks requiring real-time processing.

[Evaluation of patients using an innovative low-vision aid]. / Avaliação de pacientes utilizando equipamento inovador de auxílio à visão subnormal.

PURPOSE: To perform a preliminary evaluation at the "Clínica Oftalmológica do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (USP)" of an innovative equipment for low-vision developed at USP containing a reading stand and a magnifier that maintains in a stable position the reading line and focus. METHODS: 9 low-vision patients were evaluated using the above mentioned reading stand and a magnifier developed at USP comparing it with a hand magnifier of similar power taking into account the following evaluation parameters: etiology of low-vision, best corrected visual acuity for distance, patient's opinion comparing both low-vision aid resources, authors' opinion observing the patient using both low-vision aids. RESULTS: The numerical preference for the low-vision aids was: 5 patients for the reading stand and a magnifier that maintains at a stable position the reading line and focus; 2 patients for the hand magnifier; 1 patient indifferent regarding any of the resources; 1 patient inadequate for the evaluation of the low-vision aids. CONCLUSION: This preliminary study shows the preference of the majority of the patients for the reading stand and a magnifier that maintains at a stable position the reading line and focus showing that this innovative product makes reading easier; the evaluator doctor translates the patient's opinion as an expert and contributes to the improvement of the product so that it can be evaluated again in the future.

Avaliação de pacientes utilizando equipamento inovador de auxílio à visão subnormal / Evaluation of patients using an innovative low-vision aid

OBJETIVO: Avaliação preliminar na Clínica Oftalmológica do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (USP) de equipamento inovador para baixa visão desenvolvido na USP que consiste em prancha de leitura acoplada a lente de aumento que mantém fixos o foco e a linha de leitura. MÉTODOS: Foram avaliados 9 pacientes com visão subnormal usando o supracitado equipamento prancha de leitura acoplada a lente para auxílio em visão subnormal desenvolvida na USP em comparação com uso de uma lupa teste manual de dioptria semelhante, considerando-se os seguintes parâmetros de avaliação: causa da doença, acuidade visual corrigida no melhor olho para longe, impressão pessoal do paciente comparando prancha de leitura e lupa teste, impressão dos autores observando o uso dos 2 auxílios acima citados. RESULTADOS: A preferência pelos recursos foi: prancha de leitura acoplada a lupa - 5 pacientes; lupa manual - 2 pacientes; sem preferência por nenhum dos recursos - 1 paciente; inadequados para avaliação dos recursos preferidos - 1 paciente. CONCLUSÃO: Neste estudo preliminar, a maioria dos pacientes avaliados preferiu o recurso prancha de leitura acoplada à lupa, o que mostra que este produto inovador facilita a leitura; o médico avaliador interpreta a opinião do paciente como um especialista e contribui para o aprimoramento do produto para que ele possa ser futuramente submetido a novas avaliações.

ABSTRACT PURPOSE: To perform a preliminary evaluation at the "Clínica Oftalmológica do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo (USP)" of an innovative equipment for low-vision developed at USP containing a reading stand and a magnifier that maintains in a stable position the reading line and focus. METHODS: 9 low-vision patients were evaluated using the above mentioned reading stand and a magnifier developed at USP comparing it with a hand magnifier of similar power taking into account the following evaluation parameters: etiology of low-vision, best corrected visual acuity for distance, patient's opinion comparing both low-vision aid resources, authors' opinion observing the patient using both low-vision aids. RESULTS: The numerical preference for the low-vision aids was: 5 patients for the reading stand and a magnifier that maintains at a stable position the reading line and focus; 2 patients for the hand magnifier; 1 patient indifferent regarding any of the resources; 1 patient inadequate for the evaluation of the low-vision aids. CONCLUSION: This preliminary study shows the preference of the majority of the patients for the reading stand and a magnifier that maintains at a stable position the reading line and focus showing that this innovative product makes reading easier; the evaluator doctor translates the patient's opinion as an expert and contributes to the improvement of the product so that it can be evaluated again in the future.

Magnification labels for stand magnifiers: always misleading and usually unachievable.

BACKGROUND: Stand magnifiers (SMs) are traditionally labeled with F/4 or (F/4) + 1 magnification. This study addresses whether SMs are configured so that the assumptions associated with the labeled magnification can be realized. METHODS: Three catalogs were examined to obtain the type of magnification label used for each of 66 different SMs. Image locations were acquired from published tables compiled by independent investigators when available. Otherwise, they were taken from manufacturer-provided information in the catalogs. The image location was used to determine how many magnifiers could be used in a manner that fulfills the assumptions underlying the labeled magnification. RESULTS: For F/4 magnification, the page is assumed to be at the focal point of the SM and the image at infinity. No SMs met this condition. (F/4) + 1 magnification assumes the magnifier is close to the eye and the image is at 25 cm. Only 18% of the SMs have a 25 cm image distance. CONCLUSION: Most SMs do not have image locations that meet the conditions underlying the marked magnification. The current labeling system is inaccurate, misleading, and inefficient for clinicians. Magnification labels on SMs should be replaced with markings that include equivalent power, enlargement ratio, and image location.

Reading with optical magnifiers: page navigation strategies and difficulties.

PURPOSE: To read efficiently with a simple hand or stand magnifier, people with visual impairment have to move (navigate) the device along each line (forward phase) and back to the correct position at the start of the next line (retrace phase). Page navigation difficulties have been implicated as limiting factors when reading with hand and stand magnifiers, but have not been objectively measured. METHODS: Magnifier movements were recorded using a 3SPACE Isotrak system for 43 participants with age-related macular degeneration (AMD) who read two short stories using their habitual hand or stand magnifier. Page navigation was quantified in terms of magnifier movements and navigation errors for the forward and retrace phases. Visual acuities and visual fields were measured, and magnifier usage and page navigation difficulties were surveyed. RESULTS: During the forward phase, participants primarily used either a straight (47%) or diagonal downward (46%) movement, whereas during the retrace phase, the majority (56%) used a downward movement. On average, forward navigation time was four times longer than retrace navigation time (p<0.001). The most common navigation error was incorrect positioning of the magnifier at the end of the retrace movement. Near word acuity correlated strongly with forward time (r=0.78), and moderately with retrace time (r=0.53) and forward errors (r=0.50). Vertical field of view correlated with retrace errors (r=-0.53). Participants' estimates of page navigation difficulties were not predictive of objective measures of performance. CONCLUSIONS: We quantified page navigation strategies and difficulties of people with AMD reading with magnifiers. Retrace, which presents the most common difficulty, is not well predicted by vision measures or magnifier characteristics; future studies should investigate the relationship between motor skills and navigation performance, and the impact of training or devices on reducing retrace navigation difficulties.

[Quality control in rehabilitation of patients with visual impairment: evaluation of use and benefits of optic and electronic devices]. / Qualitätskontrolle bei der Rehabilitation sehbehinderter Patienten: Evaluation der Nutzung von Sehhilfen.

BACKGROUND: Not only medical care and prescription of magnifying devices, but also social and professional rehabilitation are part of a complete interdisciplinary low vision service. This study provides quantitative data about the success of rehabilitation and the quality of the Low Vision Department's work. PATIENTS AND METHODS: A sample of 105 visually disabled patients, who had already been provided with magnifying aids and other rehabilitation measures by the Low Vision Department, answered a questionnaire about quality control during a follow-up visit. The survey was carried out between May and October 2004. Patients were asked to rate the different rehabilitation measures and to comment on how frequently they used the different magnifying devices. Furthermore, they were asked to judge to what degree they coped with different life situations when using or not using the low vision aids. RESULTS: The most frequently used aids were magnifiers (61%), glasses for near vision (34%), closed circuit television (20%), and monocular telescopes (20%). Of the 105 patients, 85 (81%) reported on frequent use of the devices, with just 3 patients (3%) reporting that they hardly ever used the aids. Only 2% of the patients could read newspaper text without the use of magnifying aids, while 51% were able to do this using the aids; 46% of the patients reported that they had profited from the social and professional rehabilitation measures. CONCLUSION: Independently from the causal ophthalmologic diagnosis, patients were found to have benefited greatly from the rehabilitation measures provided by the Low Vision Department, enabling them to take part in more activities and participate more fully in social life, thereby greatly improving their quality of life. Frequent use of the low vision aids by the patient was ensured when offered alongside continued professional support.

Effects of overlay symbology in night vision goggles on accommodation and attention shift.

BACKGROUND: Binocular night vision goggles that have a monocular symbology overlay provide potential conflicts between perceived symbology distance and optical vergence cues for accommodation. HYPOTHESIS: Accommodative response was measured in subjects who perceived symbology nearer than the background to determine if accommodation could respond to the optical stimulus and override the perceptual cues. METHODS: Symbology was presented to the right eye under two conditions (clear and blurred to 20/50 resolution) and the background was presented binocularly with and without added speckle noise that is typical of the NVG at low light levels. RESULTS: On average, subjects accommodated by less than 0.1 diopters (D) to all 4 of the stimulus combinations even though the perceived proximal depth difference between background and symbology was 10 times greater. No perceptible blur resulted from this small change in accommodation because it is well below the depth of focus of the human eye. A control experiment illustrated that an accommodative response, at least as small as 0.25 D, could easily be stimulated optically and detected by the experimental apparatus. In a final experiment, the duration required to shift attention away from the background to a peripheral symbol, acquire critical information, and return attention to the background was 0.69 s which included saccade latency and scan time of the symbol. CONCLUSIONS: These results indicate that small changes in accommodation that occur when pilots shift attention from background to symbology do not produce perceived blur of the symbology or the background and thereby do not impair performance.

The necessary field of view to read with an optimal stand magnifier.

BACKGROUND: For most people with low vision, some form of magnification is necessary to read. Using a magnifier reduces the number of letters that can be seen simultaneously (field of view), which has been shown to decrease reading rates. This study sought to determine how many letters are necessary to attain maximal reading rates with a stand magnifier. METHODS: Younger and older normally-sighted and visually-impaired observers read short passages using a fiber optic stand magnifier (taper). The optical properties of this magnifier allowed the field of view to be precisely varied. Each subject read using at least four field sizes (3, 5, 9 and 13 characters visible) while reading speed was measured. RESULTS: Reading rates continued to increase with as many as 13 characters visible, regardless of age or vision status. In addition, reading with the taper was slower for all subject groups than reading without the magnifier. CONCLUSIONS: This study confirms reports that reading rates increase as the field of view increases when reading from a page of text. The need for this large field of view relative to other low vision reading aids (i.e., computer-generated scroll displays) is likely the result of the readers' need to actively navigate across the page of text.

Visually impaired observers require a larger window than normally sighted observers to read from a scroll display.

BACKGROUND: As text is magnified, the number of letters that can be displayed with a magnifier or other reading aid at any one time (window size) is reduced. There is a great deal of evidence that reading rates increase as the number of letters displayed increases. The minimum number of proportionally spaced letters necessary to read at maximal rates from a scroll display, in which the text is continuously panned across a television screen, is not known. METHODS: Visually impaired (VI) and normally sighted (NA) observers were asked to read either sentences or random words scrolled across a computer screen. The window size was varied so that from one to 12 characters were visible, on average, at any one time. Each subject read with six different window sizes within the range of one to 12 characters visible. RESULTS: For the NA group, a window of four to five characters was necessary to read at maximal rates. VI subjects, as a group, required a significantly larger window of six to seven characters to reach maximal reading rates. CONCLUSIONS: The window size requirement for the NA group is close to the size other investigators have reported for a fixed-width font. However, the VI group required a larger window than did the NA group, which has not been previously reported. This requirement could result from the additional stimulation available with a larger window to entrain the eyes' motion when reading from a passively scrolled display.

Stand magnifiers: an evaluation of new optical aids from COIL.

This paper discusses stand magnifiers and the optical parameters that clinicians should know in order to understand the viewing requirements and the expected resolution for low vision patients. We report on measurements made of key optical parameters of a new series of stand magnifiers from Combined Optical Industries Limited (COIL) and comparison is made to the previous series of stand magnifiers from the same manufacturer. These results illustrate that manufacturers' specifications of optical parameters are generally inaccurate and misleading. We urge manufacturers to provide clinically relevant information about their optical products.

Vibrotactile perception of segmental features of speech: a comparison of single-channel and multichannel instruments.

This experiment compared the recognition performance of artificially deafened listeners for segmental stimuli presented through a single-channel tactile device and through a 24-channel vocoder. Both consonant and vowel stimuli were tested under visual only, tactile only, and visual + tactile conditions. Each subject received a pretest, eight 2-hr training sessions, and a posttest. Results indicated no significant differences between subject's overall recognition performance with two different tactile devices. Analysis of consonant confusions showed that both devices transmit the features of voicing, manner, and place of articulation in a similar fashion. In contrast to an earlier study on suprasegmental features by Carney and Beachler (1986), these results do not support the notion that preservation of the waveform envelope of speech is necessary for the transmission of segmental features of speech. These results also suggest that tactile perception of segmental features may not be altered significantly by the tactile array chosen.

Auditory implants and tactile aids for the profoundly deaf.

This paper reviews data on speech perception via implanted electrodes and via tactile aids. The two approaches are compared in terms of amount and types of aid provided to communication. Related issues discussed are the performance levels with multi-versus single-channel implants, promontory electrical stimulators versus implants, use of minimal residual hearing, implants for children, and the possible design of complementary systems combining auditory implant and tactile information. The diversity of the test methods and subjects used in implant versus tactile research precludes definitive comparisons of speech perception performance. However, it appears from the available data that, at present and for the foreseeable future, neither approach can provide more than a modest aid to lipreading. Speech reception test results from multichannel-implanted subjects are better, on the average, than for single-channel subjects. However, the best single-channel results are comparable to the best multichannel in tests using simple sentences. There is great variation among subjects with the same implant. Tactile aid performance by highly practiced subjects seems comparable to that of the better implant subjects.