This extend abstract is a contribution to the Text Customization for Readability Symposium. The contents of this paper was not developed by the W3C Web Accessibility Initiative (WAI) and does not necessarily represent the consensus view of its membership.
Print media excludes people with low vision, and no remedy has
been shown to work reliably (Jutai, Strong & Russell-Minda,
2009). In this exhaustive and meticulous review of literature on
assistive technology, the authors found few high quality research
articles on efficacy, and among quality articles they found little
agreement. As authors of disability policy tackle electronic
access to print for low vision, they must accept a serious deficit
in the knowledge needed to support specific actions (Russell-Minda
et al., 2007). Again the authors performed an exhaustive review of
research on legibility of typeface for low vision. There
were few quality studies, and the conclusions of quality studies
did not agree.
Policy writers and developers who address issues related to low vision must accept a critical need for more and better information concerning the treatment of reading problems caused by low vision. The current article proposes a simple method to improve the knowledge base and hopefully, disability policy and assistive technology.
By definition, ophthalmology cannot treat, and optometry cannot correct low vision. To progress, research must study the presentation of text, not how well one sees it.
Psychophysics has found that font-size, font face, spacing, brightness and contrast do influence reading performance while findings on color are less certain (Legge, 2007). This research has produced clear explanations of the role of typography in reading as well as valuable metrics and measurement instruments. Of particular interest to policy authors is critical print size, the minimum print size that enables maximum reading speed. This metric can be measured accurately by the MREAD (Legge, 2007). Current policy regarding print size does not use critical print size as a metric.
Clinical research has not discovered a clear map to sound policy or assistive technology for reading with low vision (Russell-Minda et al., 2007). This author sees concrete reasons for this fact. Clinical research takes care to isolate factors to ensure accuracy. This encourages narrow hypotheses that can be refuted or accepted. The result is scientifically valid findings with limited social scope.
The value of this science is accuracy. When clinical researchers claim an intervention works they know the exact limits of efficacy. Generalization to social policy is not the goal.
In an exception to this trend, Legge & Bigelow, 2012) demonstrate that print size of running text in most commercial publications is close to the critical print size of normal readers. They posit a market ecology of normal reader preference, publication cost and available print technology to explain their result. This ecology excluded people with low vision.
Clinical rigor is absent from evaluating assistive technology (Jutai, Strong & Russell-Minda, 2009). For example, nobody can delineate the exact population of people with low vision who are served by zoom technology and high contrast. There are psychophysical indicators, but no conclusions (Russell-Minda et al., 2007). Any policy for low vision that is based on capabilities of current assistive technology has a weak clinical foundation.
It is ethical to disseminate assistive technology without conclusive proof of efficacy. For example, Europeans used eye glasses for 300 years without understanding the science of refraction (American Optometric Association, 2010). However, this lack of regulation leaves desperate people who want a cure to their reading problems with little consumer protection. Present disability policy is silent on this issue.
The term typometrics denotes the study of the typographic environments that can be used to treat the reading problems of people with print disabilities. The goal of typometrics is to develop individualized typographic environments that improve reading (typometric prescriptions). The focus is on environments, factor combinations, not isolated factors. It is engineering not basic science, and it is client centered.
The concept is simple: (1) Enable people with low vision to choose their own typographic environments. (2) Collect and analyze style parameters, user response to typographic choice, medical data and psychophysical metrics to detect patterns. (3) Evaluate the efficacy of user choice and identify exactly who is helped and who is not. (4) Develop new policy and technology based on the findings.
To develop a typometric prescription a low vision specialist
might proceed as follows. (1) Choose base color orientation:
light on dark or dark on light. (2) Refine Colors. (3) Pick the
font for running text: family, size and weight. (4) Choose the
line, letter and word spacing. (5) Set margins for running text.
(6) Element by element (paragraph, heading, list, etc.) pick
special presentations (font, color, spacing, box model,
etc.). Follow the general model used by an optometrist
interviewing a patient to converge on a prescription. Once
the prescription is found, the end user could use typometric
software to refine the results for various life situations.
For example, a larger font may be needed for reading than for
composing essays. A typometric analysis may result in
several style options for the user.
Prior to the World Wide Web this approach would be a theoretical
exercise. Typography oriented to low vision was infeasible. The
Web created fully customizable typographic style. Today, one can
adjust the presentation of accessible HTML and MathML with the
same precision optometrists prescribe lenses. In addition,
variable typography for this media can be disseminated efficiently
File formats for electronic publishing that do not support flexible typography will resist policy that requires user access to typography. Opposing this market force is impossible without quality research to support claims of user need.
This author is finishing work on a web based tool (Typometric Rx) to determine the user's typometric prescription. It will enable users full choice of the typographic format for HTML elements. The complete research program requires funding. A tool is just the first step.
The diverse medical presentation of low vision poses serious
issues for data analysis. Attaining necessary sample sizes could
At CSUN 2012, the author presented a prototype of Typometric Rx
(Dick, 2012). This year the Knowbility Floor Exhibit at CSUN
2013 will feature a completed first version of Typometric
Rx. Following the simple interview schedule above, a team
will collect prescriptions on the floor for qualitative
study. A strict protocol for protection of human subjects
will be followed.
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.
Public Policy and assistive technology for low vision are stalled. With few exceptions typographic flexibility of web language has been ignored in research, assistive technology and policy regarding low vision. Research is needed to determine efficacy of typographic intervention. Typometrics provides an engineering approach that uses basic findings of psychophysics and the flexibility of web technology. Formal clinical trials are needed to verify the efficacy of emerging assistive technologies. This should protect consumers with low vision and enable informed policy.
Legge, G. E. (2007) Psychophysics of Reading in Normal and Low Vision. Lawrence Elbaum Associates, Mahwah, NJ
Russell-Minda, E., Jutai, J. W., Strong, J. G., Campbell, K. A.,
Gold, D., Pretty, L., Wilmot, L. (2007) The Legibility of
Typefaces for Readers with Low Vision: A Research Review. Journal
of Visual Impairment & Blindness. Vol. 101, Issue 7
Jutai J.W., Strong J.G., Russell-Minda E. (2009) Effectiveness of assistive technologies for low vision rehabilitation: a systematic review. Journal of Visual Impairment & Blindness. Vol. 103, Issue 4
American Optometric Association (2010) History of Optometry. Retrieved from http://fs.aoa.org/optometry-archives/optometry-timeline.html
Dick, W. E. (2012) Typometric Rx: New for Low Vision Readers. CSUN
Conference on Technology and People with Disabilities.
Retrieved from: Sessions > General Sessions.
Legge, G. E. & Bigelow, C. A. (2012) Does print size matter for reading? A review of findings from vision science and typography. Journal of Vision. Vol. 12 Number 10, retrieved from: http://www.journalofvision.org/content/11/5/8.full