Research

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This page is to collect relevant research on low vision. Please include a summary (abstract paragraph or bullets) of the research.

Please consult the Research: Specific Issues page for information related to Legibility and Readability, Movement and Low Vision. The Placeholder Research page contains information related to that topic.

Research Issues

  • 3:1 vs 4.5:1 for graphics and user interface controls.

2018 Research

  • Gunnon, Erin. Assessing alternative text presentation and tablet device usage for low vision leisure reading, 2018.
    • Abstract:
      Low vision affects approximately 246 million people worldwide. Age-related macular degeneration (AMD) is one of the leading causes of low vision in developed countries, and the incidence is expected to rise in the next decade (World Health Organization, 2014). The most frequently cited complaint by individuals with vision loss is difficulty reading (Rubin, 2013). A loss of recreational activities like reading has been linked to reduced quality of life and depression in this population (Hazel, Latham, Armstrong, Benson, & Frost, 2000; Rovner & Casten, 2002). It is therefore imperative that research examines avenues through which those with low vision can continue to read for pleasure with minimal frustration. In a series of three studies, the present research examines reading satisfaction and low vision aid (LVA) use. Study 1 concerns reading satisfaction of low vision and normally sighted readers using a tablet computer. This study compared five variations of presenting text on the screen, and subjective measures of preference and satisfaction were emphasized. Study 2 takes a more applied approach to explore the use of three of the five presentations used in Study 1 over time. Study 3 is a survey that extends the findings of Studies 1 and 2 by measuring aspects of reading device awareness, training, satisfaction, and use among a larger sample of low vision readers. Results from Studies 1 and 2 suggest improved perceptions of alternative text formats over time, the potential value of tablet devices, and emphasize the role of enjoyment in reading. Study 3 suggests that tablets and e-readers may be under-represented in low vision rehabilitation..
  • McCoy, Erica. Accessible Web Typography for the Visually Impaired, 2018.
    • Abstract:
      Visual impairments affect millions of people worldwide. Accessible web typography is important in ensuring online legibility for this diverse group of users to help them maintain their independence. However, existing typographic guidelines are based heavily on best practices, with supported research based largely on printed typography, and rarely considers the needs of visually impaired users. The purpose of this research is to investigate which elements of typography have the most impact on visually impaired users in an effort to work towards more accessible typographic guidelines. Method: An in-depth analysis of existing online typography trends found that even with copious resources available web designers are often not adhering to typographic guidelines. This analysis helped build a solid foundation for experimental research with visually impaired users by providing insight into how typography is actually being used on the web. In response, both line height and font size were tested for their effects on simulated macular degeneration. A second experiment tested line height across three other simulated visual impairment types. Results: This study did not show significant effects on legibility for simulated macular degeneration based on font size, although error rate was nearly twice as high for smaller font sizes. Increased line height did significantly reduce the error rate for simulated macular degeneration. When increased line height was tested across other simulated visual impairments, the improvement was not statistically significant. However, this study should be repeated with a within-subjects design before these results are considered fully reliable. Conclusions: As past research has indicated, there may not be one solution for typography that fits in in regards to visually impaired users. Accommodations for the needs of one user may work against the needs of another user. With online access essential to daily tasks, though, it’s important to consider how visually impaired users interact with the web and continue to explore how enhancements to typography can benefit the distinct needs of these users.
  • Moreno, et.al. Exploring the Web navigation strategies of people with low vision, 2018.
    • Abstract:
      People with low vision experience accessibility barriers when they interact with the web. This paper explores the navigation strategies of low vision users in order to select the appropriate accessibility techniques to design web interfaces for them. For this purpose, an exploratory study was carried out with six users with low vision. The results revealed the heterogeneity in the group of people with low vision and the variety of navigation strategies applied. Observations and analysis of data gathered in experimental sessions allowed a set of techniques to be defined that can improve accessibility for people with low vision when interacting with the web.

2017 Research

  • Alotaibi, Abdullah Z. Effects of Line Spacing on Reading Performance of Normally Sighted and Simulated Visually-Impaired Subjects: A Pilot Study Using Arabic Words, 2017.
    • Abstract:
      The study aims to evaluate the role of line spacing during reading in normal and visually-impaired persons. A total of 225 normally-sighted participants with mean age of 23.7 years were asked to read Arabic sentences in a randomized order. Each Arabic sentence contains 7 lines with and without simulated cataract. The words were printed with black letters on white background to enhance contrast and fonts were in Times New Roman and of N12 letter size. The reading pages were placed on reading stand situated 25 cm away from the subject’s eyes. The simulated cataract was created by using a Bernell Cling Patch Occluder. This reduced the visual acuity of all subjects to 20/60. Each line of the text was separated by different line spacing namely: single space, 1.5, 2.0, 2.5, 3.0 and 4.0 which represents, 0.5 cm, 0.8 cm, 1.1 cm, 1.4 cm, 1.7 cm and 2.0 cm, respectively. The sheets were presented randomly and participants’ voices were recorded as they read under a controlled time. The tape was analysed later and reading rate was calculated. There was a significant difference (p<0.0001) in reading rates between the normal sighted persons and the visually impaired persons for all line spacing. Modifying the spacing between lines in prints had a significant impact (p<0.0001) on the reading rate of the visually impaired but not in normally-sighted persons (p˃0.05). Intermediate line spacing (2 and 2.5) increased the reading rate of the visually impaired persons significantly more (p<0.001) than other line spacing, but smaller or larger line spacing slowed their reading rate, significantly (p<0.001). The visually-impaired persons reported that they felt the difference in reading prints with larger line spacing as compared with normal sighted participants who did not. It is beneficial to adequately modify the line spacing in prints commonly read by low vision persons. For Arab subjects the optimum line spacing to significantly improve reading in the visually impaired should range from 0.8 to 1.1 cm. This finding may be a useful for publishers of Arab prints targeting the visually impaired persons. Thus, the implication of the study in the field of health is that by establishing the least common line spacing visualized optimally among normal and simulated visually impaired persons would be fixed as default line spacing for Arab printing to achieve better reading performance.
  • Arditi, Aries. Rethinking ADA signage standards for low-vision accessibility, ARVO Journal of Low Vision, 2017.
    • Abstract:
      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.
  • Christen and Abegg. The effect of magnification and contrast on reading performance in different types of simulated low vision, 2017.
    • Abstract:
      Low vision therapy, such as magnifiers or contrast enhancement, is widely used. Scientific evidence proving its efficacy is scarce however. The objective of this study was to investigate whether the benefits of magnification and contrast enhancement depended on the origin of low vision. For this purpose we measured reading speed with artificially induced low vision in 12 healthy subjects in conditions of a simulated central scotoma, blurred vision and oscillopsia...
  • Dick, Wayne. Operational Overhead Caused by Horizontal Scrolling Text, 2017.
    • Abstract:
      As a reader of horizontal scrolling for 59 years and a mathematician, I decided to quantify what I have always thought about the process. I started using magnifying glasses when I was 10; I moved to telescopic glasses with a hand-held lens in the mid 70’s and used CCTV. I was a beta tester for Luna in the 90’s, and have tracked the process of screen magnification software (SMS) ever since. In early 2002, I found CSS. The web was new and one user style sheet would work on about 60% of sites. In the next 10 years, I read more books and articles than I did in preceding 40 years. This article gives some quantitative insight as to why...

2016 Research

  • Calle-Jimenez, Tania; Luján-Mora, Sergio. Web Accessibility Barriers in Geographic Maps (PDF), 2016.
    • Abstract:
      ...Today, the Web is a means of basic communication, perhaps the most important, and geographic information can also be transmitted through the Web. Therefore, we must ensure that the geographic information published on the Web is accessible. However, the continuing growth of technology causes people to have difficulty in interacting with applications that present geographic information. For this reason, this study presents an analysis of the barriers to web accessibility in geographic maps, explains how technologies and tools have evolved, and proposes the use of scalable vector graphics (SVG) for the implementation of accessible geographic maps.
  • Chung, Susana T. L.; Gordon E. Legge. Comparing the Shape of Contrast Sensitivity Functions for Normal and Low Vision. 2016.
    • Abstract:
      The contrast sensitivity function (CSF) provides a detailed description of an individual's spatial-pattern detection capability. We tested the hypothesis that the CSFs of people with low vision differ from a "normal" CSF only in their horizontal and vertical positions along the spatial frequency (SF) and contrast sensitivity (CS) axes...Conclusions: The excellent agreement of parameters estimated by the two fitting methods suggests that low-vision CSFs can be approximated by a normal CSF shifted along the log-SF and log-CS axes to account for the impaired acuity and contrast sensitivity.
  • Hamade, Noura, Hodge; William G.; Rakibuz-Zaman, Muhammad; Malvankar-Mehta, Monali S. The Effects of Low-Vision Rehabilitation on Reading Speed and Depression in Age Related Macular Degeneration: A Meta-Analysis, 2016.
    • Abstract:
      ...Conclusion - A considerable amount of research is required in the area of low-vision rehabilitation strategies for patients with Age Related Macular degeneration (AMD). Based on current research, low-vision rehabilitation aids improve reading speed. However, they do not have a significant effect on depression scores in those 55 and older with AMD.
  • Legge, Gordon E. Reading Digital with Low Vision, 2016.
    • Abstract:
      ...Reading difficulty is a major consequence of vision loss for more than four million Americans with low vision. Difficulty in accessing print imposes obstacles to education, employment, social interaction and recreation. In recent years, research in vision science has made major strides in understanding the impact of low vision on reading, and the dependence of reading performance on text properties. The ongoing transition to the production and distribution of digital documents brings about new opportunities for people with visual impairment. Digital documents on computers and mobile devices permit customization of print size, spacing, font style, contrast polarity and page layout to optimize reading displays for people with low vision. As a result, we now have unprecedented opportunities to adapt text format to meet the needs of visually impaired readers.
...What about interline spacing? Two recent studies with lowvision subjects found either no benefit of extra line separation (Chung et al., 2008) or a very small advantage (Calabrese et al., 2010). But Blackmore-Wright et al. (2013) found that combining double line spacing and double between-word spacing was beneficial for subjects with macular degeneration. Overall, the evidence indicates that increasing spacing between letters is not helpful, but extra-wide spacing between lines or words may have some benefits for some readers with low vision...
  • Pundlik, Shrinivas; Magnifying Smartphone Screen using Google Glass for Low-Vision Users, 2016.
    • Abstract:
      Magnification is a key accessibility feature used by low-vision smartphone users. However, small screen size can lead to loss of context and make interaction with magnified displays challenging. We hypothesize that controlling the viewport with head motion can be natural and help in gaining access to magnified displays. We implement this idea using a Google Glass that displays the magnified smartphone screenshots received in real time via Bluetooth. Instead of navigating with touch gestures on the magnified smartphone display, the users can view different screen locations by rotating their head, and remotely interacting with the smartphone. It is equivalent to looking at a large virtual image through a head contingent viewing port, in this case, the Glass display with ~15° field of view. The system can transfer 7 screenshots per second at 8x magnification, sufficient for tasks where the display content does not change rapidly. A pilot evaluation of this approach was conducted with 8 normally sighted and 4 visually impaired subjects performing assigned tasks using calculator and music player apps. Results showed that performance in the calculation task was faster with the Glass than with the phone’s built-in screen zoom. We conclude that head contingent scanning control can be beneficial in navigating magnified small smartphone displays, at least for tasks involving familiar content layout.
  • Verma, Kamal Mohan; Tondon M.P. Evaluation of low vision and its rehabilitation in various disorders, 2016.
    • Conclusion:
      The incidence of low vision is mostly underestimated due to lack of knowledge about this condition...
  • Szpiro, Sarit Felicia Anais ; Hashash, Shafeka ; Zhao, Yuhang ; Azenkot, Shiri. "How People with Low Vision Access Computing Devices: Understanding Challenges and Opportunities, 2016.
    • Abstract:
      Low vision is a pervasive condition in which people have difficulty seeing even with corrective lenses. People with low vision frequently use mainstream computing devices, however how they use their devices to access information and whether digital low vision accessibility tools provide adequate support remains understudied. We addressed these questions with a contextual inquiry study. We observed 11 low vision participants using their smartphones, tablets, and computers when performing simple tasks such as reading email. We found that participants preferred accessing information visually than aurally (e.g., screen readers), and juggled a variety of accessibility tools. However, accessibility tools did not provide them with appropriate support. Moreover, participants had to constantly perform multiple gestures in order to see content comfortably. These challenges made participants inefficient-they were slow and often made mistakes; even tech savvy participants felt frustrated and not in control. Our findings reveal the unique needs of low vision people, which differ from those of people with no vision and design opportunities for improving low vision accessibility tools.
  • Szpiro, Sarit; Zhao, Yuhang; and Azenkot, Shiri. Finding a store, searching for a product: a study of daily challenges of low vision people 2016.
    • Abstract:
      ....We sought to answer two research questions: (1) what challenges do low vision people face when performing daily activities and (2) what aids (high- and low-tech) do low vision people use to alleviate these challenges? Our goal was to reveal gaps in current technologies that can be addressed by the UbiComp community. Using contextual inquiry, we observed 11 low vision people perform a wayfinding and shopping task in an unfamiliar environment. The task involved wayfinding and searching and purchasing a product. We found that, although there are low vision aids on the market, participants mostly used their smartphones, despite interface accessibility challenges. While smartphones helped them outdoors, participants were overwhelmed and frustrated when shopping in a store. We discuss the inadequacies of existing aids and highlight the need for systems that enhance visual information, rather than convert it to audio or tactile.

2015 Low Vision Research

  • Bonavero, Yoann; Huchard, Marianne; and Meynard; Michel. Reconciling user and designer preferences in adapting web pages for people with low vision, 2015.
    • Abstract:
      ...In this paper, we focus on people with low or weakening vision, for whom we propose to adapt web pages to their needs, while preserving the spirit of the original design. In this context, obtaining a web page adaptation in a very short time may be a difficult problem, because user and designer needs and preferences may contradict each other, and because there may be a large number of adaptation possibilities. Finding a relevant adaptation in a large search space can hardly be done by an algorithm which computes and assesses all possible solutions, which brings us to consider evolutionary algorithms. A characteristic of our problem is to consider a set of preferences, each being implemented by an evaluation function. This optimization problem can be dealt with multiobjective genetic algorithms, including the Non-dominated Sorting Genetic Algorithm II (NSGA-II) and its next version (NSGA-III). NSGA-III has been recently introduced to address many-objective optimization problems (having more that four objectives). We compare NSGA-II and NSGA-III performances in the context of adapting web pages in accordance to a set of preferences. The comparison is based on running time, number of generations and quality of computed adaptation (number of satisfied objectives). We also show the importance of several parameters including population size, crossover/mutation probability, and the opportunity to aggregate objective functions. From the obtained results, we conclude that the approach is feasible and effective on realistic web pages, especially with NSGA-III.
  • Hallett, E.; Arnsdorff, B.; Sweet, J.; Roberts, Z., Dick, W.; Jewett, T.; & Vu, K.L. The usability of magnification methods: A comparative study between screen magnifiers and responsive web design., 2015.
    • Abstract:
      Screen magnifiers, which often result in the need for horizontal scrolling, and enlarging content through the browser itself are two magnification methods used by computer-users with low vision. With responsive web design (RWD), the later can be done with word wrapping, thus eliminating the need to horizontally scroll. The present study compared the effectiveness of the two methods when participants performed two types of Web-based tasks: reading comprehension and data input. Results showed that when using RWD, participants completed the reading comprehension tasks more quickly and accurately compared to when using screen magnifiers. Participants were also able to complete data input more quickly with RWD than with the screen magnifier. Finally, participants rated RWD to be more usable than screen magnifiers. The results of this study have implications for further developments of web accessibility guidelines.
  • Halletta, Elyse C.; Robertsa, Zach; Sweeta, John; Chana, Mei Ling; Suna, Yuting ; Dick, Wayne; Mongea, Alvaro; Vu, Kim-Phuong L. Computer Accessibility: How Individuals with Low Vision Adjust the Presentation of Electronic Text for Academic Reading, 2015.
    • Abstract:
      Low vision has been defined as impaired vision that cannot be fully corrected by eyewear, medication, or surgery. Depending on the type and severity of the eye condition inducing impaired vision, the resulting perceptual experience can range vastly. Because of the wide range in perceptual experiences, one method for altering the presentation of text may not be a sufficient accommodation for all computer users with low vision. The present study sought to understand the tools that individuals with low vision currently use and how these individuals customize the presentation of content when reading academic text. Four students and two college graduates were interviewed about their visual conditions, assistive technologies, and methods for extended reading. Results indicate that the visual experience determines what assistive technologies are useful and how text is customized so as to be readable. The manner in which content is presented influences whether an individual with low vision will experience eyestrain, fatigue, and headaches, and thus determine how long the task will be worked on. Participants indicated that the variety of different assistive technologies and varying customization methods are all exercised with the same end-goal in mind: to make the content perceivable and readable. The varying needs of individuals should be both understood and supported in the design of assistive technologies. Failure to do so could prevent equal access to individuals with low vision.
  • Hallett, Elyse C. Reading without bounds: How different magnification methods affect the performance of students with low vision, 2015.
    • Abstract:
      Computer users with low vision must use additional methods to enlarge content in order to perceive content comfortably. One common method is a screen magnifier, which typically requires horizontal scrolling. Another method is through the web browser zoom controls, and with the coding technique, responsive web design (RWD), content remains within the browser window as it is enlarged. The purpose of the present study was to assess how the different magnification methods affect reading comprehension and visual fatigue of people with low vision when reading on a computer screen. After reading on a screen magnifier for about an hour, participants tended to report higher levels of nausea. Younger participants also completed the second half of reading passages quicker than the first with this method. This finding was likely due to a strong aversion for using a screen magnifier for extended periods of time due to the need to horizontally scroll.
  • Rosen D., Norenberg E., Carlson L., Angelos P. et. al. University of Minnesota Duluth Learning Product Usability Evaluation Summary Report, 2015.
    • Issues include: The tools are difficult to navigate; Visual contrast issues; Navigation is unclear; One tool doesn’t adjust well to use of Windows Zoom; iconography without labels leads to confusion and misidentification; Contextual changes on the screen, like error, messages, are unseen when using ZoomText; Inconsistent use of header elements.
  • Nielsen, Jakob. Legibility, Readability, and Comprehension: Making Users Read Your Words, 2015.
    • Summary:
      Users won’t read web content unless the text is clear, the words and sentences are simple, and the information is easy to understand. You can test all of this.

2014 Low Vision Research

  • Bonavero, Yoann; Huchard, Marianne; and Meynard, Michel. Improving Web Accessibility: Computing New Web Page Design with NSGA-II for People with Low Vision, 2014.
    • Abstract:
      ...In the specific case of people with low vision, efforts to improve e-accessibility are mainly focused on the provision of third-party tools. Assistive technologies like screen magnifiers adapt graphical user interfaces to increase the quality of the perceived information. However, when these technologies deal with the Web, they are not able to meet all specific needs of people with low vision. In this paper, we propose an approach to make Web pages more accessible for users with specific needs. User preferences can concern font size, font family, text color, word and letter spacing, link color and decoration or even more complex features regarding brightness, relative size or contrast. We also take into account and encode the designer's graphical choices as designer preferences. Solving preferences of the user and of the designer to obtain a new Web page design is an optimization problem that we deal with Non-dominated Sorting Genetic Algorithm II (NSGA-II), a polynomial Multi-Objective Genetic Algorithm. We conducted detailed tests and evaluated the running time and quality of results of our tool on real Web pages. The results show that our approach for adapting Web page designs to specific user needs with NSGA II is worthwhile on real Web pages.
  • Carlson, L., et. al. University of Minnesota Duluth Home Page Accessibility/Usability Evaluation Report, 2014.
    • Key point regarding time-on-task:
      On average people with disabilities expended approximately 3 times more effort (168 seconds versus 52 seconds) than people without disabilities per task.
  • Dick, Wayne E.; Gadberry, Darnell; and Monge, Alvaro. Adjusting Typographic Metrics to Improve Reading for People with Low Vision and Other Print Disabilities (PDF), 2014.
    • Abstract:
      A new software technique called typometrics is presented. This enables users to choose a wide range of typographic metrics to assist reading. A software implementation called TRx (Typometric Prescription) is described. TRx is a style authoring tool for web languages. Designed for use by assistive technology (AT) specialists and users with print disabilities, this software enables users to create personal reading environments with all the range of style available to authors of documents. The article concludes with a description of a three part study planned to collect baseline data for implementing typometric interventions to improve reading.
  • Harvey, Hannah; and Walker, Robin. Reading with peripheral vision: A comparison of reading dynamic scrolling and static text with a simulated central scotoma, 2014.
    • Abstract:
      Horizontally scrolling text is, in theory, ideally suited to enhance viewing strategies recommended to improve reading performance under conditions of central vision loss such as macular disease, although it is largely unproven in this regard. This study investigated if the use of scrolling text produced an observable improvement in reading performed under conditions of eccentric viewing in an artificial scotoma paradigm. Participants (n = 17) read scrolling and static text with a central artificial scotoma controlled by an eye-tracker. There was an improvement in measures of reading accuracy, and adherence to eccentric viewing strategies with scrolling, compared to static, text. These findings illustrate the potential benefits of scrolling text as a potential reading aid for those with central vision loss.

2013 Low Vision Research

  • Blackmore-Wright, S., Georgeson, M. A., & Anderson, S. J. Enhanced text spacing improves reading performance in individuals with macular disease 2013.
    • Abstract:
      ...We recommend that macular disease patients should employ double line spacing and double-character word spacing to maximize their reading efficiency.
  • Henry, Shawn Lawton. User Research Survey on Changing Text Display for Easier Reading, 2013.
  • Kaklanis, Nikolaos et al. Touching open street map data in mobile context for the visually impaired (PDF) 2013.
    • Abstract:
      In this paper, authors present an application that enables access to OpenStreetMap data for the visually impaired and blind users using a common mobile device (e.g. smart phone, tablet) that runs on Android, is presented. During map exploration, as user moves his/her finger on the touchscreen of the mobile device, he/she receives vibration feedback when finger is on a road or a point of interest (POI), while a sonification and a TTS module, provide audio feedback regarding the distance to the next crossroad and the name of current road/POI, respectively."
  • Kulpa, Cinthia Costa; Teixeira, Fabio Goncalves; and Da Silva, Régio Pierre. A Color Model in the Usability of Computer Interface Applied to Users with Low Vision (PDF) 2013.
    • Abstract:
      This paper presents the results of a research on the usability of computer interfaces through colors for Low Vision users. It describes the methodology used, the 3 web interfaces tested fo r usability with the users in question, showing the results for the development of a prototype interface with colors as the main aspect. The prototype developed is presented with the usability test carried out with it. As a result of the work, a proposed color model is presented that includes Low Vision users in the construction and upgrading of computer interfaces, aimed at the usability of web interfaces."
  • Oyamada, Marcio; Bidarra, Jorge; and Boscarioli, Clodis. PlatMult: a multisensory platform with web accessibility features for low vision users, 2013.
    • Abstract:
      Screen magnifiers are the usual assistive technology for low vision users in computer interaction. However, even using a screen magnifier, low vision users have serious limitations for web access. In order to mitigate this problem, we propose a multisensory platform called PlatMult, composed of visual, auditory, tactile feedback. The PlatMult provides a screen magnifier, integrated with a screen reader, and an adapted mouse with motor feedback. The feedback is fired in an integrated way; for instance, when the user moves the mouse over links and buttons in a webpage, the PlatMult activates the screen reader and the mouse motor feedback. This paper describes the components developed in order to obtain the accessible events from the Firefox web browser.
  • Pelli, D. G. \; Bex, P. Measuring contrast sensitivity. Sept. 2013
    • Contrast sensitivity is impaired in ophthalmic conditions including myopia (Collins & Carney, 1990), glare (Abrahamson & Sjöstrand, 1986), cataract (Hess & Woo, 1978), amblyopia (Freedman & Thibos, 1975), age-related macular degeneration (Kleiner et al., 1988), ocular hypertension (Gandolfi, 2005), glaucoma (Stamper, 1984) and dry eye (Rolando et al., 1998). Contrast sensitivity can also be impaired in neurological conditions, including cerebral lesions (Bodis-Wollner, 1972), multiple sclerosis (Regan et al., 1981), Parkinson’s disease (Bodis-Wollner & Onofrj, 1986) and schizophrenia (Cimmer et al., 2006). Furthermore, contrast sensitivity loss is a common side-effect of many prescription drugs (Li et al., 2008 ; Santaella and Fraunfelder, 2007). Some contrast sensitivity deficits can be remedied by optical, pharmaceutical, surgical, or rehabilitative intervention.
  • Smith, Jared; et al. WebAIM Survey Results, 2013.
    • Conclusion:
      This data shows very diverse demographics and opinions among those with low vision. Respondents used a wide variety of assistive technologies, with most respondents using multiple technologies. For designers and developers, there is no single tool, technique, or approach to meeting the needs of this population. And great care should be taken in implementing solutions for this audience which may impact usability or accessibility for other site users.
  • Neilsen, Jakob Seniors as Web Users
    • Abstract: Users aged 65 and older are 43% slower at using websites than users aged 21–55. This is an improvement over previous studies, but designs must change to better accommodate aging users.
Seniors Users Aged 21–55
Success rate 55.3% 74.5%
Time on task (min:sec) 7:49 5:28
Errors 2.4 1.1
Subjective rating (1–7, 7 best) 4.1 4.6

2012 Low Vision Research

  • Dick, Wayne E. Discovering Typographic Environments for Reading with Low Vision, 2012.
    • Outcomes:
      ...By developing custom user style sheets for people with low vision, this author has found that typographic adjustments appear to help some individuals. Very few trends have emerged. Increased font size is consistent, but contrast levels are not. The ability to style individual document elements means that one can substitute styles that are easier to read for disturbing formats like italics. Screen space, always precious, can be saved by using font face instead of font size to distinguish headings from running text.
  • Henry, Shawn Lawton. CSS for Readability: Analysis of user style sheets to inform understanding users' text customization needs, 2012.
    • Abstract:
      This paper provides information to help answer the question: What aspects of text display do users need to be able to customize in order to read effectively? It focuses on the largest group of people with print disabilities: those who can see and can read, but have difficulty reading text in common designs and thus need to specify different text characteristics (World Health Organization 2011, Steinmetz 2006); including: people with low vision, people with declining eyesight due to ageing, and people with dyslexia and other reading-related impairments.
  • Henry, Shawn Lawton. Developing text customisation functionality requirements of PDF reader and other user agents, 2012.
    • Abstract:
      This paper addresses the text customisation needs of people with low vision, dyslexia, and related conditions that impact reading, including people with declining eyesight due to ageing. It reports on a literature review and an initial study that explores the aspects of text that users customize (e.g., size, colour, leading, linearization/reflow, and more) for reading RTF and PDF documents, in operating system settings, and in web browser settings. ...
  • Lee, Seunghyun (Tina); and Sanford, Jon. Gesture interface magnifiers for low-vision users, 2012.
    • Abstract:
      This study compared different types of magnification and navigation methods on low-vision handheld magnifiers to determine the feasibility of a touch screen gesture interface. The results show that despite the fact that participants had no experience using gestures for magnification or navigation, participants were more satisfied with them. Gestures were faster and more preferred than the indirect input methods for pushing a button or rotating a knob, which had previously been familiar to participants from other electronic device interfaces. The study suggests that the use of gestures may afford an alternative and more natural magnification and navigation method for a new user-centric low vision magnifier.
  • Legge, Jordon E.; and Bigelow, Charles A. Does print size matter for reading? A review of findings from vision science and typography, 2012.
    • Abstract:
      The size and shape of printed symbols determine the legibility of text. In this paper, we focus on print size because of its crucial role in understanding reading performance and its significance in the history and contemporary practice of typography. We present evidence supporting the hypothesis that the distribution of print sizes in historical and contemporary publications falls within the psychophysically defined range of fluent print size—the range over which text can be read at maximum speed. The fluent range extends over a factor of 10 in angular print size (x-height) from approximately 0.2° to 2°. Assuming a standard reading distance of 40 cm (16 inches), the corresponding physical x-heights are 1.4 mm (4 points) and 14 mm (40 points). We provide new data on the distributions of print sizes in published books and newspapers and in typefounders' specimens, and consider factors influencing these distributions. We discuss theoretical concepts from vision science concerning visual size coding that help inform our understanding of historical and modern typographical practices. While economic, social, technological, and artistic factors influence type design and selection, we conclude that properties of human visual processing play a dominant role in constraining the distribution of print sizes in common use.
  • Ley, Eileen Rivera. When One Size Fits One — A Position Paper on Achieving Readability for People with Low Vision Through Web Text Customization, 2012.
    • Conclusion:
      The challenge of achieving true text customization cannot be overestimated. Even when standards for best practices for e- text customization are established, they must be disseminated and promoted to insure broad acceptance. Implementation will require new Text Customization Accessibility guidelines, as well as appropriate government regulations. Each must echo the requirements that all e-text must be customizable. With text customization, one size does not fit all, rather 'one size fits one'. Text customization guidelines must leverage the power of technology to deliver the optimal web reading experience for people with low vision.
  • Ludi, Stephanie; Canter, Alex; Ellis, Lindsey; and Shrestha, Abhishek. Requirements gathering for assistive technology that includes low vision and sighted users, 2012.
    • Abstract:
      Accessibility often concerns compatibility with third-party software in order to meet the needs of users who are disabled. The AccessLecture project seeks to transform the Apple iPad into a tool to make Math and Science class more accessible to visually impaired students. Accessing lecture material during lecture is a challenge to low vision students, in terms of the limited options that can be costly or can allow access only upon the completion of the lecture. This paper presents the techniques used to help the team gather the needs and tasks of math/science instructors and visually impaired students. The analysis of the environment, user groups and the tasks related to the course lecture were modeled in order to ascertain domain knowledge and to specify the system's requirements.
  • Mereuta, Alina; Aupetit, Sebastien; and Slimane, Mohamed . Improving Web Accessibility for Dichromat Users through Contrast Preservation, 2012.
    • Abstract:
      ...The perception of colors by a dichromat user is different. This results in a loss of the information conveyed by color. In our study, we show that there is a significant loss of contrast for a dichromat user resulting in information loss. We propose a method based on a mass-spring simulation to modify the colors with aim to enforce similar contrast for dichromat users. Tests on several websites allow us to conclude that our method significantly reduce the loss of contrast for both protanope and deuteranope users.

2011 Low Vision Research

  • Levin, L. A., D., Adler, F. H. Adler's Physiology of the Eye E-Book, 2011.
    • For high-contrast, high-illumination targets, acuity is reduce by about a factor of 1.8 in the older group (80-85) (i.e. the “m” must be about 1.8 times larger). Low-contrast acuity with glare is reduce by about a factor of 3 in the younger (60-65) group, but by almost a factor of 7 in the older group…. High-contrast visual acuity greatly underestimates the true age-related decline in vision, and that older persons with good standard visual acuity may be visually impaired under conditions of reduced contrast, reduced lighting, changing light level or reduced contrast in the presence of glare.

2010 Low Vision Research

PURPOSE:It has been suggested that crowding, the adverse low-level effect due to the proximity of adjacent stimuli, explains slow reading in low-vision patients with absolute macular scotomas. According to this hypothesis, crowding in the vertical dimension should be released by increasing the vertical spacing between lines of text. However, studies with different experimental paradigms and only a few observers have given discrepant results on this question. The purpose of this study was to investigate this issue with a large number of patients whose macular function was carefully assessed.

METHODS: MP1 microperimetry examination was performed for each low-vision patient. Only eyes with an absolute macular scotoma and no foveal sparing (61 patients with AMD, 90 eyes; four patients with Stargardt disease, eight eyes) were included. Maximal reading speed was assessed for each eye with French sentences designed on the MNREAD test principles.

RESULTS: The effect of interline spacing on maximal reading speed (MRS) was significant although small; average MRS increased by 7.1 words/min from standard to double interline spacing. The effect was weak irrespective of PRL distance from the fovea and scotoma area and regardless of whether an eccentric island of functional vision was present within the scotoma.

CONCLUSIONS: Increasing interline spacing is advisable only for very slow readers (<20 words/min) who want to read a few words (spot reading). Vertical crowding does not seem to be a major determinant of maximal reading speed for patients with central scotomas.
  • Choudhury, Anustup; Medioni, Gerard. Color contrast enhancement for visually impaired people (PDF), 2010.
    • Abstract:
      We propose an automatic color contrast enhancement algorithm that improves the visual quality of static images for both normally sighted people and for low-vision patients. Existing methods have been shown to work on people either with normal vision or with low vision. Due to the framework of this approach, an enhanced visual experience can be simultaneously provided to normally sighted people and low vision patients. This method is inspired from human color perception and separates the image into illumination and reflectance components. It then enhances only the illumination component while trying to achieve color constancy thus resulting in color contrast enhancement. We have simulated low-vision patients by asking normally sighted people to wear simulation AMD glasses. Experiments with static images revealed that both normally sighted people and low vision patients preferred enhanced images over original images. Comparison of the enhanced images with the original images showed a statistically significant improvement in the perceived image quality due to enhancement, for subjects with normal vision and for subjects with low vision. 1.
  • Vitale S., Cotch M. F., Sperduto R. D. (2010). Prevalence of Visual Impairment in the United States. Journal of the American Medical Association, Vol 295, No. 18, Retrieved from http://jama.jamanetwork.com/article.aspx?articleid=202836
    • Abstract: Abstract
  • CONTEXT: The prevalence of visual impairment in the US public has not been surveyed nationally in several decades.
  • OBJECTIVE: To estimate the number of US individuals aged 12 years or older who have impaired distance vision due to uncorrected refractive error.
  • DESIGN, SETTING, AND PARTICIPANTS: The National Health and Nutrition Examination Survey (NHANES), using a multistage probability sampling design, included a vision evaluation in a mobile examination center. Visual acuity data were obtained from 13,265 of 14,203 participants (93.4%) who visited the mobile examination center in 1999-2002. Visual impairment was defined as presenting distance visual acuity of 20/50 or worse in the better-seeing eye. Visual impairment due to uncorrected refractive error was defined as (presenting) visual impairment that improved, aided by automated refraction results, to 20/40 or better in the better-seeing eye.
  • MAIN OUTCOME MEASURES: Presenting distance visual acuity (measured with usual corrective lenses, if any) and distance visual acuity after automated refraction.
  • RESULTS: Overall, 1190 study participants had visual impairment (weighted prevalence, 6.4%; 95% confidence interval [CI], 6.0%-6.8%), and of these, 83.3% could achieve good visual acuity with correction (95% CI, 80.9%-85.8%). Extrapolating these findings to the general US population, approximately 14 million individuals aged 12 years or older have visual impairment (defined as distance visual acuity of 20/50 or worse), and of these, more than 11 million individuals could have their vision improved to 20/40 or better with refractive correction.
  • CONCLUSIONS: Visual impairment due to uncorrected refractive error is a common condition in the United States. Providing appropriate refractive correction to those individuals whose vision can be improved is an important public health endeavor with implications for safety and quality of life.

2009 Low Vision Research

  • Foti, Antonella and Santucci, Giuseppe. Increasing Web accessibility through an assisted color specification interface for colorblind people (PDF), 2009.
    • Abstract:
      Nowadays web accessibility refers mainly to users with severe disabilities, neglecting colorblind people, i.e., people lacking a chromatic dimension at receptor level. As a consequence, a wrong usage of colors in a web site, in terms of red or green, together with blue or yellow, may result in a loss of information. Color models and color selection strategies proposed so far fail to accurately address such issues. This article describes a module of the VisAwis (VISual Accessibility for Web Interfaces) project that, following a compromise between usability and accessibility, allow color blind people to select distinguishable colors taking into account their specific missing receptor.
  • Nguyen, Nhung Xuan; Weismann, Malte; and Trauzettel-Klosinski, Susanne. Improvement of reading speed after providing of low vision aids in patients with age-related macular degeneration, 2009.
    • Abstract:
      PURPOSE: Age-related macular degeneration (AMD) is the most common cause of severe visual impairment, including loss of reading ability, among elderly persons in developed countries. The aim of the present study was to evaluate reading ability before and after providing of appropriate low vision aids....CONCLUSION: Our results indicate the great value of low vision rehabilitation through adequate providing of vision aids for the improvement of reading ability, with a highly significant increase of reading speed without training of eccentric viewing in patients with retained central fixation. The prompt implementation of low vision aids in patients with macular degeneration will help them to maintain and regain their reading ability, which can lead to an increase in independence, communication, mental agility and quality of life.
  • Wang, Meng; Liu, Bo; Hua; Xian-Sheng. Accessible image search, 2009.
    • Abstract:
      There are about 8% of men and 0.8% of women suffering from colorblindness. We show that the existing image search techniques cannot provide satisfactory results for these users, since many images will not be well perceived by them due to the loss of color information. In this paper, we introduce a scheme named Accessible Image Search (AIS) to accommodate these users...

2008 Low Vision Research

  • Candido, Jacqueline P. Visual Impairment in a Visual Medium Perspectives of online learners with visual impairments (PDF), 2008.
    • Statement of the Purpose:
      The purpose of this study is to explore and describe the ways that postsecondary students with visual impairments experience online learning. The researcher expects to show the benefits and difficulties that people with visual impairments experience in college-level online learning. This study will examine how adult learners with vision impairments accommodate the daily challenges they encounter in the online classroom.

2007 Low Vision Research

  • Arditi, Aries; Cho, Jianna; Letter case and text legibility in normal and low vision; 2007.
    • Abstract:
      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.
  • Jenny, Bernhard; Kelso Nathaniel Vaughn, Color Design for the Color Vision Impaired (PDF), 2007.
    • Abstract:
      Eight percent of men are affected by color vision impairment – they have difficulties distinguishing between colors and thus confuse certain colors that the majority of people see readily. Designers of maps and information graphics cannot disregard the needs of this relatively large group of media consumers. This article discusses the most common forms of color vision impairment, and introduces Color Oracle, a new software tool that assists the designer in verifying color schemes. Color Oracle filters maps and graphics in real-time and efficiently integrates with existing digital workflows. The paper also discusses color combinations and alternative visual variables for map symbology that those with color vision impairments can distinguish unambiguously. The presented techniques help the cartographer produce maps that are easy to read for those with color vision impairments and can still look good for those with normal color vision.
  • McLeish, Eve. A Study of the Effect of Letter Spacing on the Reading Speed of Young Readers with Low Vision, British Journal of Visual Impairment, 2007.
    • Abstract:
      The aims of this study were two-fold: firstly, to establish a method of applying consistent letter spacing to documents using MS Word, and secondly, to investigate the effect of increased letter spacing on the reading speeds of readers with low vision. Tests on 14 readers with low vision showed that increased letter spacing benefited their reading speed and also reduced the critical print size of the majority of subjects tested. These findings could have a significant impact on the format of modified large print material used by low-vision readers in mainstream schools and lead to more inclusive practise in the classroom. Additionally, a simple to follow table has been produced to quantify the effect of increased letter spacing in MS Word. Although MS Word is almost universally used in mainstream schools to modify teaching resources, for low-vision readers, the method of applying letter spacing and its effect are not clear.
  • Jutai, Jeffrey W.; Strong, J. Graham; and Russell-Minda, Elizabeth. Effectiveness of Assistive Technologies for Low Vision Rehabilitation: A Systematic Review (PDF), 2007.
    • Abstract:
      A systematic review of all types of assistive devices indicated the need for more research related to performance measurements and the effectiveness of vision rehabilitation devices.
  • Russell-Minda, Elizabeth; Jutai, Jeffrey W.; Strong, J. Graham; Campbell, Kent A.; Gold, Deborah; Pretty, Lisa; and Wilmot, Lesley. The Legibility of Typefaces for Readers with Low Vision: A Research Review (PDF), 2007.
    • Abstract:
      This article presents a systematic review of the research evidence on the effects of the characteristics of typefaces on the legibility of text for adult readers with low vision. The review revealed that research has not produced consistent findings and thus that there is a need to develop standards and guidelines that are informed by evidence.

2006 Low Vision Research

  • Dick, Wayne E. Using cascading style sheets to accommodate websites for individuals with low vision, 2006.
    • Abstract:
      The Web Community tolerates bad markup for visual effect even when the practice excludes partially sighted users. This paper describes a two-phase process to recondition websites: deconstruction and building a new skin. It uses cascading style sheets. Deconstruction replaces developer styles with good defaults for partially sighted users. Building a new skin customizes the site for individual preferences. It adjusts font size, font family, color configuration, line height, word spacing and letter spacing. Its styles for lists and tables aid navigation. The process works best on sites that conform to W3C standards. Even marginal sites can be transformed so that the new interface is pleasant so long as the site developer does not misuse markup too aggressively.
  • Dini, S., Ferlino, L., Gettani, A. et al. Educational software and low vision students: evaluating accessibility factors, 2006.
    • Abstract:
      The aim of this paper is to draw a few guidelines for the evaluation of the accessibility and usability of educational software programs from the point of view of low vision students...
    • Abstract:
      The aim of this paper is to draw a few guidelines for the evaluation of the accessibility and usability of educational software programs from the point of view of low vision students...
  • Jefferson, Luke; Harvey, Richard.Accommodating color blind computer users, 2006.
    • Abstract:
      Important visual information often disappears when color documents are viewed by color blind people. The algorithm introduced here maps colors using the World Wide Web Consortium evaluation criteria so that detail is preserved for color blind viewers, especially dichromats. The algorithm has four parts: 1) select a representative set of colors from the source document; 2) compute target color distances using color and brightness differences; 3) solve an optimization step that preserves the target distances for a particular class of color blind viewer; and 4) interpolate the mapped colors across the remaining colors in the document. We demonstrate the efficacy of our method using simulations and critique our method in the context of earlier work.

2005 Low Vision Research

  • Bergel, Marguerite; Chadwick-Dias, Ann; LeDoux, Lori, and Tullis, Tom. Web Accessibility for the Low Vision User, 2005
    • Abstract:
      While usability research focuses mainly on sighted users and somewhat on blind users with assistive devices, little is known about the needs of low vision users. The goal of this study was to determine if we could design an interface that would specifically address the needs of low vision users and improve both their performance and overall user experience. We incorporated visual and audio help, the ability to increase text size, and the ability to view the site in reverse contrast into the interface of a prototype financial services site. Help (elicited on mouse over) was added to all links and some additional Web page components, and provided detailed information regarding the destination content for each component. Thirteen low-vision users completed 8 tasks on the live financial services site and 8 on the prototype financial services site. Performance and subjective data were collected and compared between sites. While there were no significant differences in performance between sites, users rated the prototype site (with user help options) significantly more positively than the live site and appeared more facile in navigating the prototype than the live site.
  • Theofanos, Mary Frances; and Redish, Janice (Ginny). Helping Low-vision and Other Users with Web Sites That Meet Their Needs: Is One Site for All Feasible?, 2005.
    • Abstract:
      For this study, we recruited low-vision users with a variety of vision problems who need software to magnify computer text. Although we did not systematically recruit for specific vision problems, the fact that our users had different needs gave us one of the most critical insights in this study: The needs of low-vision users are too diverse for simple solutions to Web accessibility and usability. We show a few ways in which today’s Web sites are missing the needs of all low-vision users and provide guidelines for fixing those problems. However, the diversity of vision needs and the resulting adaptations that low-vision users require mean that there are no simple solutions to making Web sites work for everyone. In this article, therefore, you will not find many simple guidelines. Instead, we raise a critical issue and suggest a “vision of the future” solution.

2003 Low Vision Research

  • Blaikie AJ, Ravenscroft J, Buultjens M, Dutton GN, Visual Impairment Scotland Research Group. Visual Field Loss in Children. May 2003
    • "The three most common types of visual field loss described were ‘peripheral’ (34%), ‘lower’ (29%) and hemianopia (21%)."
    • "Just under half the children (47%) acquired the impairing condition prenatally and one quarter (25%) around the time of birth. Very few children (14%) acquired the cause of the impairment after the first month of life."
  • Owsley, Cynthia , Contrast sensitivity Ophthalmology Clinics of North America. 2003. Vol 16
    • The amount of contrast a person needs to see a target is called contrast threshold. Contrast thresholds can be measured for several types of visual decision making tasks, such as simple detection (is something there), discrimination (are two things the same or different), recognition (is something familiar), or identification (what is the target). Typically the detection threshold for a target is the lowest contrast threshold, though there can be exceptions when, for example, the thresholds for detecting and identifying a target are practically identical.

2002 Low Vision Research

  • National Research Council (US) Committee on Disability Determination for Individuals with Visual Impairments; Lennie P, Van Hemel SB, editors. Visual Impairments: Determining Eligibility for Social Security Benefits National Academies Press (US), 2002.
    • Has a number of citations and covers a number of topics including contrast in tasks beyond reading.
    • Tests of visual functions are at the core of current disability determination practices for visually impaired claimants at the Social Security Administration (SSA), and the committee's task required us to carefully review and evaluate these tests. This chapter presents the results of that review...

2001 Low Vision Research

  • Bernard, Michael, Liao, Chia Hui, Mills, Melissa. The effects of font type and size on the legibility and reading time of online text by older adults, 2001.
    • Abstract:
      This study examined passages containing two serif and sans serif fonts at 12 and 14-point sizes for differences in legibility, reading time, and general preference when read by an older population. A significant main effect of size was found for font legibility in that 14-point fonts were more legible to read than 12-point fonts. A marginal interaction was also found for reading time in that participants read 12-point serif fonts significantly slower than 14-point serif or sans serif fonts. Moreover, participants significantly preferred the 14-point to the 12-point font size. Font recommendations are discussed.

2000 Low Vision Research

  • Jacko, Julie A.; Barreto, Armando B.; Marmet, Gottlieb J.; Chu, Josey Y. M.; Bautsch, Holly S.; Scott, Ingrid U.; and Rosa, Robert H. Jr. Low vision: the role of visual acuity in the efficiency of cursor movement, 2000.
    • Abstract:
      Graphical user interfaces are one of the more prevalent interface types which exist today. The popularity of this interface type has caused problems for users with poor vision. Because usage strategies of low vision users differ from blind users, existing research focusing on blind users is not sufficient in describing the techniques employed by low vision users. The research presented here characterizes the interaction strategies of a particular set of low vision users, those with Age-related Macular Degeneration, using an analysis of cursor movement. The low vision users have been grouped according to the severity of their vision loss and then compared to fully sighted individuals, with respect to cursor movement efficiency. Results revealed that as the size of the icons on the computer screen increased, so did the performance of the fully sighted participants as well as the participants with AMD.

2004 Microsoft Forrester

Research About Accessibility Accessible Technology in Computing—Examining Awareness, Use, and Future Potential

Key Findings

  • 57% of computer users are likely or very likely to benefit from the use of accessible technology.
  • 44% of computer users use some form of accessible technology.
  • Users seek solutions to make their computers easier to use, not for solutions based on their health or disability.
  • Making accessibility options easier to discover and use will result in computers that are easier, more convenient, and more comfortable for computer users.

1998 Low Vision Research

  • Bangor, Aaron W. Improving Access to Computer Displays: Readability for Visually Impaired Users 1998.
    • Abstract:
      In the field of human factors engineering the issue of how to present electronic text to people has been studied intensely for over 35 years. However, one major consideration that has largely been overlooked in these studies is how visual impairments affect reading of computer text. Specifically, the issue of how text can be modified to improve readability of CRTs for individuals with low vision. A 2x5x2x3 (visual capability, font size, polarity, and contrast) mixed-factor, repeated-measures experimental design was used to determine if changes in font size, contrast polarity, and/or contrast can improve reading speeds and reduce error rate for people with low vision. The results of this experiment show that alterations in text can be made that do not affect unimpaired vision readers while dramatically improving the reading capabilities of the impaired vision population. For character size, 12 and 14 point font sizes were found to be too small for the visually impaired population examined. In general, 18 and 30 point font sizes were equal to each other and to the 24 point font size, but for some interactions these two were found to produce longer response times and higher error rates. Thus, a 24 point font size is recommended.Unlike previous research with visually impaired participants, this experiment found that negative (white-on-black) polarity worsened reading performance. It is thought that this discrepancy is a result of polarity's interaction with small font sizes. For this reason, it is recommended that for font sizes of 18 points and below, positive polarity should be used. For 24 and 30 point sizes either polarity is satisfactory, though previous research (Legge, Pelli, Rubin, and Schleske, 1985b; NRC, 1995; Rubin and Legge, 1989) suggests negative polarity might be better for some visually impaired readers. Contrasts of 3:1, 7:1, and 18:1 were used in this experiment and had no significant effect for either vision group. However, contrast did significantly interact with both font size and polarity. For font sizes of 18 points or below, it is recommended that contrasts of 18:1 be used for either polarity, but this is very important if negative polarity is used. The above recommendations are based on a small group of impaired vision readers. Visual impairments vary widely and the sample used in this experiment represented only a portion of them, with respect to both cause and severity. Wherever possible, computer text should be tailored to the unique needs of its users.

1997 Low Vision Research

  • Legge, Gordon E.; Ahn, Sonia J.; Klitz, Timothy S.; and Luebker, Andrew. Psychophysics of reading—XVI. The visual span in normal and low vision (PDF), 1997.
    • Abstract:
      The visual span in reading is the number of characters that can be recognized at a glance. The shrinking visual span hypothesis attributes reading speed deficits in low vision, and slow reading in normal vision at low contrast, to a reduction in the visual span. This hypothesis predicts that reading time (msec/word) becomes increasingly dependent on word length as text contrast decreases. We tested and confirmed this prediction using the rapid serial visual presentation (RSVP) method. Estimates of the visual span ranged from about 10 characters for high-contrast text to less than two characters for low-contrast text. Eye-movement recordings showed that longer reading times at low contrast are partitioned about equally between prolonged fixation times and an increased number of saccades (presumably related to a reduced visual span). RSVP measurements for six out of seven low-vision subjects revealed a strong dependence of reading time on word length, as expected from reduced visual spans.

1995 Low Vision Research

  • Kline, Richard L.; and Glinert Ephraim P. Improving GUI accessibility for people with low vision, 1995.
    • Abstract:
      We present UnWindows V1, a set of tools designed to assist low vision users of X Windows in effectively accomplishing two mundane yet critical interaction tasks: selectively magnifying areas of the screen so that the contents can be seen comfortably, and keeping track of the location of the mouse pointer. We describe our software from both the end user's and implementor's points of view, with particular emphasis on issues related to screen magnification techniques. We conclude with details regarding software availability and plans for future extensions.

1993 Low Vision Research

  • Wurm, Lee H.; Legge, Gordon E.; Isenberg, Lisa M.; and Luebker, Andrew. Color improves object recognition in normal and low vision (PDF), 1993.
    • Abstract:
      Does color improve object recognition? If so, is the improvement greater for images with low spatial resolution in which there is less shape information? Do people with low visual acuity benefit more from color? Three experiments measured reaction time (RT) and accuracy for naming food objects displayed in 4 types of images: gray scale or color, and high or low spatial resolution (produced by blur). Normally sighted Ss had faster RTs with color, but the improvement was not significantly greater for images with low spatial resolution. Low vision Ss were also faster with color, but the difference did not depend significantly on acuity. In 2 additional experiments, it was found that the faster RTs for color stimuli were related to objects' prototypicality but not to their color diagnosticity. It was concluded that color does improve object recognition, and the mechanism is probably sensory rather than cognitive in origin.

1990 Low Vision Research

  • Holyoak Kitchel, Elaine. Colored Light and Low Vision, 1990.
    • Abstract:
      Choices of UV filters and NoIR filters from 60 low-vision subjects were obtained from clients receiving services within Indiana Blind and Visually Impaired Section, Indiana Vocational Rehabilitation Services, Bosma Industries for the Blind and persons at large. Another group of 20 subjects was selected among non-visually impaired employees who worked for those institutions to provide a comparison. Subjects were asked to select for eye comfort, and contrast from among the following filters provided by NoIR Medical technologies: U50 (yellow), U81 (medium plum), U80 (dark plum), U21 (medium grey), U70 (pink), 102 (medium grey green), U10 (clear), U93 (red), U60 (orange), U22 (dark grey), 101 (amber), 708 (dark grey green). Twenty-eight percent of the experimental group chose medium plum filters, 25% chose yellow, with pink being chosen at a rate of 13%. Clients had been asked to select filters in standard indoor light and medium-to-bright outdoor light and judge filters according to the following criteria: Best contrast achieved and eye comfort. Determinations were then made about which persons most often chose which filters based on statistical frequency. Subjects performed a daily task while wearing the filters in order to determine if the filters actually helped improve contrast or eye comfort. It was found that the subjects who suffered from macular degeneration, glaucoma, retinitis pigmentosa most often chose yellow filters. Persons with histoplasmosis, toxoplasmosis and the category of "other" which consisted mostly of refractive errors and retinopathy most often chose plum, with plum being the most chosen color overall. Filters of red, green, orange and clear all were chosen by at least one subject. Grey was preferred by the control group overwhelmingly. Dark grey, amber, and dark grey green were not selected by any subjects with visual impairments.
  • Legge, G.E., Parish, D.H., Luebker, A., & Wurm, L.H. (1990). Psychophysics of reading. XI. Comparing luminance and color contrast (PDF)
    • Abstract:
      Text can be depicted by luminance contrast (i.e., differences in luminance between characters and background) or by color contrast (i.e., differences in chromaticity). We used a psychophysical method to measure the reading speeds of eight normal and ten low-vision subjects for text displayed on a color monitor. Reading speed was measured as a function of luminance contrast, color contrast (derived from mixtures of red and green), and combinations of the two. When color contrast is high, normal subjects can read as rapidly as with high luminance contrast (>300 words/min). Curves of reading speed versus contrast have the same shape for the two forms of contrast and are superimposed when contrast is measured in multiples of a threshold value. When both color and luminance contrast are present, there is no sign of additive interaction, and performance is determined by the form of contrast yielding the highest reading rate. Our findings suggest that color contrast and luminance contrast are coded in similar ways in the visual system but that the neural signals used in letter recognition are carried by different pathways for color and luminance. We found no advantages of color contrast for low-vision reading. For text composed of 60 characters, all low-vision subjects read better with luminance contrast than with color contrast.
  • Pastoor, Siegmund. Legibility and Subjective Preference for Color Combinations in Text, 1990.
    • Abstract:
      This study examined legibility performance and subjective preference for text/background color combinations displayed on a video monitor. Luminance contrast was fixed at two preoptimized levels, either with text brighter than the background (10:1) or vice versa (1:6.5). In Experiment 1, 32 subjects rated about 800 color combinations. No evidence suggested differential effects of luminance polarity or hue, with the only exception that cool background colors (blue and bluish cyan) tended to be preferred for the light-on-dark polarity. Saturation had the most important influence on ratings. Any desaturated color combination appears to be satisfactory for text presentation. In Experiment 2 a reduced set of 18 color combinations was investigated with a new sample of 18 subjects. Reading and search times as well as multidimensional ratings were evaluated. There was no evidence for an influence of luminance polarity or chromaticity on performance. Subjective ratings corresponded well with the results of Experiment 1.

1989 Low Vision Research

  • Rubin, G S., Legge G E. Psychophysics of Reading: VI. The Role of Contrast in Low Vision (PDF), 1989.
    • Abstract:
      The effect of contrast on reading performance was measured in 19 low-vision observers with a wide range of visual disorders and degrees of vision loss. The observers read text composed of 6 deg letters, ranging in contrast from 0.96 down to contrast threshold for reading. Reading performance was characterized by two parameters: peak reading rate is the reading rate at maximum contrast, and critical contrast is the contrast at which reading rate drops to half its maximum value. Peak reading rates were lower in observers with central field loss than in observers with intact central vision. In 16 of 19 cases, critical contrasts were higher for low-vision observers than for normal observers (averaging 3.9 times higher), indicating a decreased tolerance to contrast reduction. Values of critical contrast were closely linked to contrast sensitivity for letters (r = 0.87), but did not vary systematically with type of vision loss. Five observers read white-on-black text faster than black-on-white at both high and low contrasts. Four of the five had cloudy ocular media. We attribute this contrast polarity effect to abnormal light scatter in eyes with cloudy media. We examined the hypothesis that our low-vision observers' deviation from normal performance could be characterized (1) by a contrast scaling factor representing an attenuation of effective contrast and (2) that this scale factor could be identified with reduced contrast sensitivity. Such a description provided a good account for subjects with cloudy ocular media, where contrast attenuation results from intraocular light scatter. It provided a first order, but incomplete account for subjects with field loss where contrast attenuation is related to contrast sensitivity losses due to neural factors."
      Abstract from Pub Med

1987 Low Vision Research

  • Bailey, Ian L; Boyd Lawrence, H; Boyd Wesley, L.; and Clark, Marleen, Readability of computer display print enlarged for low vision, 1987.
    • Abstract:
      A letter counting task was presented on a Macintosh computer screen using two different versions of 24 point Times Roman print. One version, called "grainy," had 12 matrix units per font height and the other, called "smooth," had 24. A mixed group of low vision subjects and a normally sighted group had speed and accuracy measured as they performed the test task from two different viewing distances. For both population groups, the remote test distances were arranged individually so that the letters subtended an angular size scarcely larger than threshold. The close distances were fairly representative of practical working distances. It was shown that, for both groups of subjects, smooth letters allowed faster performance for the closer working distances only. Smoothing the letters helped accuracy of performance at the far distances, and at the close distances, smoothing improved the accuracy for the low vision group but not for the normals. The implications are discussed.

1986 Low Vision Research

  • Legge, G.E. & Rubin, G.S. Psychophysics of reading. IV. Wavelength effects in normal and low vision. (PDF) 1986.
    • Abstract:
      Does the color of text influence its legibility? There are reasons why it may do so for specific groups of low-vision observers. We used psychophysical methods to measure the effects of wavelength on the reading performance of four normal observers, two dichromats, and twenty-five low-vision observers. Reading rates were measured for text scanned across the face of a television (TV) monitor. We compared performance under four luminance-matched conditions in which sets of neutral-density and Wratten color filters were placed in front of the TV screen-blue (max = 430 nm), green (Xmax = 550 nm), red (Ama = 650 nm), and gray. Under photopic conditions, the reading rates of normal subjects were independent of wavelength, with the exception of characters near the acuity limit. At lower luminances, wavelength effects could be explained by the shift from photopic to scotopic vision. It was hypothesized that light scatter or absorption in eyes with cloudy ocular media would result in depressed perfor- mance in the blue. Only one of seven subjects demonstrated this effect, which we traced to wavelength-specific absorption. Observers with advanced photoreceptor disorders tended to read blue text faster than red text. This could not be explained on the basis of photopic spectral sensitivities alone. Finally, the presence of central or peripheral field loss was not predictive of wavelength-specific effects in reading. On the whole, wavelength only occasionally plays a significant role in reading. When it does, performance tends to be depressed either in the red or the blue and to be nearly optimal for green or gray.
    • Summary:
      We have asked whether wavelength affects reading performance. We have found that, with the possible exception of letters near the acuity limit, the reading performance of normal subjects under photopic conditions is independent of wavelength. Our deuteranope behaved normally, but our protanope exhibited a reduced reading rate in the red. This reduction can be accounted for by the protanope's reduced photopic spectral sensitivity in the red...

1985 Low Vision Research

  • Legge, Gordon E.; Rubin, Gary S.; Pelli, Denis G.; and Schleske, Mary M. Psychophysics of reading—II. Low vision, 1985.
    • Abstract:
      Very little is known about the effects of visual impairment on reading. We used psychophysical methods to study reading by 16 low-vision observers. Reading rates were measured for text scanned across the face of a TV monitor while varying parameters that are likely to be important in low vision: angular character size, number of characters in the field, number of dots composing each character, contrast polarity (white-on-black vs black-on-white text), and character spacing. Despite diverse pathologies and degrees of vision loss in our sample, several major generalizations emerged. There is a wide variation in peak reading rates among low-vision observers, but 64% of the variance can be accounted for by two major distinctions: intact central fields vs central-field loss and cloudy vs clear ocular media. Peak reading rates for observers with central-field loss were very low (median 25 words/minute), while peak reading rates for observers with intact central fields were at least 90 words/minute (median 130 words/minute). Most low-vision readers require magnification to obtain characters of optimal size. Sloan M acuity was a better predictor of optimal character size than Snellen acuity, accounting for 72% of the variance. Low-vision reading is similar to normal reading in several respects. For example, both show the same dependence on the number of characters in the field. Our results provide estimates of the best reading performance to be expected from low-vision observers with characteristic forms of vision loss, and the stimulus parameters necessary for optimal performance. These results will be useful in the development of clinical tests of low vision, and in the design of low-vision reading aids.

1981 Low Vision Research

  • Owsley, C.; Sekuler R.; Boldt C,. Aging and low-contrast vision: face perception., August 1981
    • Abstract
      Previous work showed that despite good visual acuity, many healthy older people require more contrast to see gratings of low and intermediate spatial frequencies than do younger observers. Here we report that a daily perceptual activity, which relies on lower spatial frequency information, is also adversely affected: as compared to young individuals, many older individuals require more contrast to detect a face and to discriminate between two faces. Ocular pathology, optical changes within the eyeball, and variation in criterion are ruled out as explanations for the age-related elevation in threshold.