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The legibility of typefaces for readers with low vision: a research review.

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.

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Reading is critical to full participation in modern society, and as the population ages, the concern for the print accessibility of public documents will rise. For the many individuals with vision loss, reading print presents a major challenge when planning and performing everyday tasks. In Canada, the 2001 Participation and Activity Limitation Survey (PALS) reported that of the approximately 600,000 people with "seeing disabilities," most have low vision, and that roughly 500,000 people aged 15 and older require accommodations to read newsprint, such as special lighting, large print, or magnification (Statistics Canada, 2001). According to demographic information from the 2000 U.S. census, an estimated 937,000 Americans aged 40 and older were blind (U.S. definition) and 2.4 million had low vision in 2000. The leading causes of blindness and low vision in the United States in adults aged 40 and older were age-related macular degeneration (AMD), cataract, and glaucoma (Eye Diseases Prevalence Research Group, 2004).

The International Council of Ophthalmology's report, Visual Standards: Aspects and Ranges of Vision Loss (Colenbrander, 2002), recommended that the global vision community use the term low vision for degrees of vision loss less than blindness when individuals can be helped significantly by vision-enhancement aids and devices and that when detailed reporting on the ranges of vision loss are not feasible, the range for low vision should be less than 6/18 (0.3) (20/60) and greater than or equal to 3/60 (.05) (20/ 400). Low vision has also been described as the inability to read a newspaper or recognize faces from a conventional reading distance (40 centimeters, or about 16 inches) while wearing the best refractive correction (Chung, Mansfield, & Legge, 1998). Many older people have difficulty reading standard print, including medication labels, even with appropriate magnification and illumination. High levels of magnification can reduce the size of the usable field for many individuals with low vision, and the manipulation of the characteristics of typefaces can reduce or eliminate the need for additional magnification (Arditi, 2004).

Previous research on the legibility of typefaces and psychophysical variables related to it has suggested that certain characteristics can affect legibility and reading acuity for both sighted readers and those with low vision (Arditi, 1996; Arditi, Knoblauch, and Grunwald, 1990; Legge, Rubin, and Luebker, 1987; Tinker, 1963). These characteristics include the presence or absence of serifs (Arditi & Cho, 2000, 2005); the width of strokes (Arditi, Cagnello, & Jacobs, 1995b; Berger, 1944a, 1944b); kerning or interletter spacing (Arditi et al., 1995a; Arditi, Liu, & Lynn, 1997; Moriarty & Scheiner, 1984; Whittaker, Rohrkaste, & Higgins, 1989); leading (the space between lines of text) (Tinker, 1963); point size (Legge, Rubin, Pelli, & Schleske, 1985); the height of letters (x-height, defined as the vertical measure of the lowercase "x" in any given font, and t-height, defined as the height of the bottom of the crossbar of the letter "t" in any given font) (Arditi, 2005); contrast (Rubin & Legge, 1989); and color (Legge & Rubin, 1986).

The legibility and readability of fonts have been studied by examining the individual characteristics of a font or differences among whole or unmodified fonts (Arditi et al., 1990; Mansfield, Legge, & Bane, 1996; Morris, Berry, Hargreaves, & Liarokapis, 1991). Research on the specific characteristics of fonts, such as stroke width or the use of serifs, requires the manipulation of individual parameters while keeping others constant. Alternatively, researching whole fonts may be easily done in practical application, but limits the generalizability to specific characteristics. When the characteristics of fonts are evaluated, the outcome may be contaminated because of the difficulty in knowing whether the reported differences in legibility are related to the size of the type, to different lighting conditions, or to fundamental differences in design.

One concept of the legibility of print specifies that the test material should be performed under "threshold seeing conditions," a psychophysical acuity measurement that defines a threshold value at which a majority of subject responses are accurate. Another concept is related to the performance of various typeface designs when they are presented at sizes that are well above the reader's threshold. One aspect to be considered may be simply which font design is the most appealing or comfortable to the reader, often described as "readability" (Arditi, 2005; Kitchel, 2002). A significant problem arises when one font design "A" is found to be more legible than another font design "B," but font "B" is found to be more readable than "A." The apparent contradiction may be explainable by the inconsistent use of terms. Other criteria that are used to determine the legibility of typefaces are reading speed and critical print size (Chung et al., 1998; Mansfield et al., 1996). The critical print size is the smallest print size at which individuals can read with their maximum reading speed. This is an important measure because it indicates the minimum magnification that is required for effortless reading.

With this overview of research and performance measures in mind, the primary objectives of this review were to locate any research related to the effective characteristics of typefaces for readers with low vision, to determine the existence of any standards or guidelines that are related to such legibility, and to address the characteristics of French-language typefaces for readers with low vision. The latter was considered because French uses a number of accent marks that are not used in English, and the typeface that is used may make these marks more distinct or less distinct, and Canada, the country in which this research was conducted, is officially a bilingual country. In addition, research related to the legibility of medication labels was considered.

By incorporating methods that are frequently used in systematic reviews, we rated and synthesized the selected literature to formulate conclusions and make recommendations. Although this review is not typical of other evidence-based reviews that have been used in clinical-trials research environments, we incorporated methods that have been used in systematic reviews by integrating specific protocols when searching for studies, developing targeted criteria for inclusion and exclusion, and using systematic methods for rating the quality of studies. The methods used in this review were consistent with previous work related to the Vision Rehabilitation Evidence-Based Review project; see the web site <www.piads.ca/112/vrebr.htm> for details on the parent project of this article.

Methods

SELECTION OF STUDIES

Literature searches were conducted on the following primary databases: the Cumulative Index to Nursing and Allied Health Literature; Evidence-Based Medicine Reviews, which includes the Cochrane Database of Systematic Reviews and the Cochrane Controlled Trials Register; EMBASE; MEDLINE-OVID; and PubMed. Searches of secondary databases and the "gray" literature were also conducted. Typically, gray literature is any type of unpublished research and may include governmental, business, or academic theses, bibliographies, conference papers or abstracts, technical reports, and standards or best-practice documents. The specific sources of gray literature that we searched for this review included unpublished and published governmental, business, technical, or academic reports, as well as standards or best-practices documents. To locate standards or guidelines on the legibility of text, we searched all potential sources. The keywords used were specific to visual impairment and the legibility and characteristics of typefaces. No limits were set on the year of publication.

The primary inclusion criterion for the selection of research was that the study should address issues related to the legibility and characteristics of typefaces for readers with low vision using any type of medium (printed materials or electronically displayed text). All types of low vision conditions were considered, including the most prevalent age-related ocular conditions that pose difficulties when reading print, such as AMD, cataract, diabetic retinopathy, and glaucoma. All types of study designs were considered: controlled and uncontrolled; experimental and nonexperimental; randomized controlled trials and nonrandomized controlled trials; meta-analyses of randomized controlled trials, published or unpublished; and systematic or standard literature reviews. Secondary inclusion criteria included any international guidelines or standards that have been established for the legibility of typefaces for those who are print disabled and considerations of French typefaces. Although extremely important for users with low vision, research related to factors that are associated with computer accessibility issues was excluded. The search parameters were limited to the following criteria: English language, with no specific limits on participants' ages or years of publication. The search was limited to literature in English and studies related to the characteristics of French-language type, and was search concluded in March 2006.

Abstracts were independently reviewed by two of the authors and rated by the study designs, based primarily on the organizational model proposed by the Canadian Task Force on the Periodic Health Examination (1979) and the Oxford Centre for Evidence-Based Medicine <www.cebm. net>: (I) randomized controlled trials, systematic reviews, or meta-analyses; (II) cohort and nonrandomized experimental studies; (III) case control studies; (IV) case series and descriptive studies; (V) experts' opinions without critical appraisal or based on physiology, bench results, or "first principles"; and (VI) "gray literature." We decided to include an additional level of evidence to accommodate gray literature sources. The studies we selected were primarily nonrandomized or experimental designs or unpublished reports (with or without controls), and further ratings with an instrument for assessing the quality of the studies were not performed. Meta-analyses or comparisons of effect sizes on the selected studies were not conducted because of the heterogeneity of interventions, outcomes, and study designs.

Results

SEARCH RESULTS

We selected and reviewed 18 studies from a total of 184 that met the inclusion criteria and represent a wide array of research designs and methodologies (see Table 1). Comprehensive tables of the studies' attributes were created by extracting data from each study (this data is available by request from us). No randomized controlled trials were located. The excluded 166 studies failed to meet the primary and secondary inclusion criteria outlined in the Methods section. No evidence regarding the legibility of French typefaces was found. We located no definitive, evidence-informed literature on font-legibility standards or guidelines for low vision reading materials.

CHOICE OF TYPEFACE AND FONT SIZE

In one of the few quantitative studies on the legibility of fonts and the reading performance of persons with low vision, Mansfield et al. (1996), using whole fonts printed on high-contrast charts, found a small, but significant, advantage of Courier over Times Roman in reading acuity, critical print size, and reading speed. Gains in reading speed were modest, and it is possible that for print sizes that are close to the acuity limit, the choice of typeface could make a significant difference in the reading performance of persons with low vision. Arditi (2004) found that modified fonts using prototype font-adjustment software (Font Tailor) enhanced legibility, on average, by more than 75%. The study did not demonstrate any advantage over standard fonts, such as Times New Roman.

Yager, Aquilante, and Plass (1998) found that 16 out of 20 sighted participants could read an unmodified Swiss (sans serif) font more rapidly than an unmodified serifed Dutch typeface, displayed on a monitor with high contrast. The lower-case x-height of the fonts was approximately 5.5 times as large as the letter acuity, and the acuity reserve for Swiss was higher than for Dutch viewed in low luminance conditions, which may have accounted for the difference in reading speeds. The study also found that letters with a uniform stroke width appear to be more legible.

Chung et al. (1998) measured the effect of print size on the reading speed of persons with typical peripheral vision using unmodified fonts, displayed in high contrast, on a monitor. The results showed that a larger print size was required to achieve the maximum reading speed in peripheral than in central vision. Research has shown that readers with low vision require larger print (of at least 16- to 18-point type), although there is no consensus on the optimum character size for large-print publications. For sighted readers, at a usual reading distance of 40 centimeters or about 16 inches, type sizes ranging from of 9 to 14 points are best (Legg, Rubin, Pelli, & Schleske, 1985). The range of visual ability is highly variable from one individual to the next, and reading thresholds are individualized.

In a series of experiments comparing the customized Tiresias large-print type-face to Arial and Times Roman, Perera (2001) found that in nearly all the trials, the participants preferred the large-print typeface, Tiresias, over Arial or Times Roman. Most of the experiments used whole, unmodified fonts, with the exception of the serif, space and weight, and punctuation exercises. All text was printed on paper. The participants with poor reading vision preferred Tiresias more than did those with good vision in experiments comparing the legibility (serif and typeface), space, and weight of typefaces and punctuation. In addition, Campbell et al. (2005) reported that across a total of 398 participants, a 16-point, unmodified sans serif font, called "Adsans," was found to be more readable than Times Roman, indicating that familiarity with a popular typeface did not correlate with a preference for legibility or readability. All text in the experiment was on paper or on medication bottles and labels.

The American Printing House for the Blind (APH) recommends the use of its APHont font when creating large-print materials for individuals with low vision because of its usability characteristics: even spacing between letters, no serifs, wider letters, rounder letters, and larger punctuation marks. We did not locate any experimental, published studies on APHont but did inspect a brief report related to large-print guidelines and APHont found on the APH web site (Kitchel, 2004). In addition to specialized typefaces created for large-print materials, research has been conducted on the legibility of highway signs with consideration for night vision, high-brightness materials, and aging drivers. The Clearviewhwy typeface was created to decrease a phenomenon called irradiation by increasing the spacing between letters without decreasing the distance at which the characters are legible (Garvey, Pietrucha, & Meeker, 1997). Since highway signage was not part of our inclusion criteria for selecting studies, we did not assess the research literature on this subject. Overall, the best available evidence, based on experimental research and subjective preferences, suggests that typefaces such as Arial, Helvetica, Verdana, and Adsans are more readable than is Times New Roman, for example (as measured by reading performance and subjective preferences). It is also evident that readers with low vision require at least a 16- to 18-point type, although there appears to be no consensus on the optimum character size for large-print publications.

SERIF OR SANS SERIF?

The results from research on the effects of the presence or absence of serifs on the legibility of print seem to be inconclusive. Frequently, the research had not held constant particular typeface characteristics, such as stroke width, size, or ornamentation (Woods, Davis, & Scharf, 2005). Both Arditi and Cho (2005) and Moriarty and Scheiner (1984) found no differences in reading speed with sans serif and serif fonts. Arditi and Cho (2000), using nine customized fonts printed in lowercase on paper and displayed on a monitor, found an extremely small effect of the size of serifs in one experiment. With small letter sizes, close to the acuity limit, serifs may actually interfere, although slightly, with legibility. However, there was no strong determination of a definite difference in legibility between serif and sans serif fonts. Moriarty and Scheiner used unmodified fonts, printed on a sales brochure, with regular and close letter spacings.

When Morris, Aquilante, Yager, and Bigelow (2002) compared 4- and 16point modified Lucida fonts, they found that serifs appeared to interfere only at small sizes and did not contribute anything to sentence-based word recognition through Rapid Serial Visual Presentation (RSVP) reading software. The participants viewed the text on a computer display at 4 centimeters (about 2 inches), corresponding to approximately 4-point and 16-point type at a normal reading distance of 40 centimeters (about 16 inches). They concluded that serifs may slow RSVP reading at small retinal sizes and may be counterproductive. Yager et al. (1998) and Perera (2001) found that the participants' reading performance improved when they read text printed in the unmodified Swiss and Tiresias typefaces, respectively. The participants also preferred the sans serif fonts. Campbell et al. (2005) reported a preference for sans serif fonts (unmodified), as determined by the rating and ranking of readability tasks. Although the research evidence does not enable us to make strong conclusions about the readability or legibility of serif or sans serif fonts, there appears to be a subjective preference among readers with low vision for sans serif fonts.

CROWDING AND LETTER CONFUSION

Individuals with central vision loss (caused by conditions such as AMD) read with peripheral vision or used eccentric viewing strategies. Some studies have shown that reading rates among those using the peripheral visual field are slower than those reading with central vision, possibly because of enhanced crowding in peripheral vision. Crowding refers to the decreased visibility of a visual target in the presence of nearby objects (Cline, Hofstetter, & Griffin, 1997). Some studies have suggested that increased letter spacing may reduce this "crowding effect" and increase reading speeds when peripheral vision is used (Chung, 2002). Most of the knowledge on the "crowding effect" has come from letter-identification experiments in which observers either knew which letter in the display was the target or knew how many letters they were supposed to report from a stimulus string (Liu & Arditi, 2000). Using five different letter spacings, Chung found that increased kerning beyond the standard for letter spacing did not lead to an increase in reading speed in central or peripheral vision in sighted participants when text was displayed on a computer monitor using the RSVP method. Using a color-monitor display, Liu and Arditi (2000, 2001) observed that under narrow-spacing conditions, random guessing and lateral interactions between features of neighboring letters accounted for most of the deterioration in acuity. When information about the length of letter strings was uncertain, the participants tended to underestimate the lengths of small, closely packed letter strings. Moriarty and Scheiner (1984) found that a higher overall average number of words were read when messages were set with close and regular spacing. However, they could not support their hypothesis that the interaction between letter spacing and typeface affects reading speed.

Eccentric viewing reading performance may be enhanced for people with central vision loss by optimizing letter-recognition conditions. Some studies have sought to investigate this concept by studying letter-recognition tasks and analyzing letter-recognition errors--or "confusions." In MacKeben's (2000) study, frequently confused letter pairs of the Sloan set of 10 (letters C, D, H, K, N, O, R, S, V, and Z) were displayed 8 degrees to the fight of the fovea on a computer monitor, set in Arial Bold, and, for some experiments, modified using typeface creation software. Sloan "optotypes" refer to 10 letters (sans serif, on a 5" X 5" grid) originally selected for their similar levels of legibility for use in visual acuity charts. For unmodified Arial Bold, O [left and right arrow] D and H [left and right arrow] N were found to be among the most frequently confused letter pairs for the majority of subjects. Letters were then modified by doubling the width of the horizontal stem on the "H," to make it less likely to be confused with "N," and by adding serifs to the "D," to make it less likely to be confused with "O." By modifying the features of just these two letters in a set of 10, the mean recognizability was, on avearage, improved by 18.7%. Using interletter spacing variations and widths of letter strings with METAFONT, Liu and Arditi (2000) found that the participants made more mistakes in judging the number of letters in the stimulus strings as interletter spacing decreased. Liu and Arditi (2001) showed that there were particular common letter confusions for both narrow and wide letter spacings, as well as confusions that were unique to either narrow or wide spacings. According to the research evidence, it appears that for individuals with low vision, including those who use eccentric viewing strategies, there is an overall advantage in reading performance of including adequate spacing between letters. Although the results from the research assessed in this review are inconclusive, adequate spacing between letters may help reduce confusions among letters.

MEDICATION LABELS AND PRINTED HEALTH MATERIALS

Smither and Braun (1994) investigated the reading speed and subjective preferences of participants who read labels on medication bottles in Century Schoolbook, Courier, and Helvetica (unmodified typefaces), with 9-, 12-, and 14-point type and two weights, bold and Roman. The results pointed to better performance and overall preference for 12-point Century Schoolbook in boldface. For the second experiment, which used flat surfaces, the results indicated a preference for both Century Schoolbook and Helvetica, 12- or 14-point type, in boldface. Drummond, Drummond, and Dutton (2004) observed that participants with a best-corrected visual acuity lower or equal to 6/24 (20/80) had a significantly diminished ability to read instructions on their eyedrop bottles. The participants preferred Arial font (unmodified) in sizes ranging from 16 to 22 points, according to various acuity levels.

In a study of the preferences of potential cataract patients for printed materials, Estey, Jeremy, and Jones (1990) found that 65% of the participants found 14-point Universe font to be the most legible, compared to Century Schoolbook. The participants preferred the high-contrast reading materials, with black text on a white background, on the printed materials. Campbell et al. (2005) showed that in comparing six different typefaces (unmodified) in 7-point type on sample over-the-counter medication inserts and labels, the participants preferred a sans serif typeface (Adsans). Evidence based primarily on individual preferences suggests the benefits of using sans serif typefaces, with no smaller than a 12-point type, in boldface, for both medication bottles and flat surfaces. However, it is difficult to make strong evidence-informed conclusions as to the most suitable typeface, point size, and weight for medication labels. We could not locate any established or evidence-informed guidelines or standards related to the characteristics of typefaces for medication labels or printed health information.

Discussion

In summary, historical evidence from typographical research has typically not taken people with low vision into account, and the results of the research cannot always be applied to readers with low vision. This review found that the strongest evidence available from the research literature was associated with the following statements about the choice of particular characteristics of typefaces that can affect legibility: sans serif typefaces, such as Arial, Helvetica, Verdana, or Adsans, are more readable than is Times New Roman, for example; readers with low vision require at least a 16- to 18-point type for maximum readability and legibility; on the basis of subjective preferences, sans serif typefaces tend to be more readable or legible than are serif typefaces; evidence points to an overall advantage in reading performance and a reduction in letter confusion with adequate letter spacing; and on the basis of individual preferences, the use of a sans serif typeface, in no smaller than a 12-point type font, in boldface, provides the most readable conditions for both medication bottles and flat-surface labels and health literature.

With respect to technological advances in research designs, it has been only within the past decade that computers have been able to provide researchers with better control over the design of typefaces. Modifications of fonts are a necessary element for experimental research, and they are made possible through the use of computerized fonts and software, but with obvious differences in legibility between printed text and displayed text, primarily because of display variables. If font size is the variable, then research conducted at typical reading distances is difficult because of inadequate screen resolution. Although significant improvements have been made in the research because of technological advances in the manipulation of typefaces, the amount of experimental literature in this area is still limited.

Clearly, the choice of typefaces and the characteristics of fonts can affect legibility and the reading performance of individuals with low vision. In terms of which ones are the best for reading performance, some information has been proved scientifically, and some is still open to debate. Some aspects of the legibility of print appear to be dependent on subjective preference and comfort. The presence or absence of serifs, contrast between the text and the page, the thickness of letters, interletter spacing, leading, and the medium on which text is printed can all affect the legibility of type. The purpose of this review was not to promote one reading method over another. It is important to note, however, that on the basis of current research and specific conditions (ophthalmologic or age), appropriate magnification--through the use of low vision devices and large print--can enhance the reading performance of individuals with low vision. With an ever-increasing aging population, printed materials will need to be universally accessible to all types of people and in all types of public documents. Current guidelines on good design for printed materials for people with low vision are extremely beneficial, and there is growing enlightenment among the sighted community and public and private organizations of the need to keep pace with these developments. It is perhaps only a matter of time before standardized concepts on the legibility of text for people with low vision are instituted on both the local and global scale.

The research on which this article was based was supported, in part, by a grant from the Canadian National Institute for the Blind (CNIB). The contents of this article are solely the responsibility of the authors and do not necessarily represent the official views of CNIB.

References

Arditi, A. (1996). Typography, print legibility and low vision. In B. Rosenthal & R. Cole (Eds.), Remediation and management of low vision (pp. 237-248). St. Louis, MO: Mosby.

Arditi, A. (2004). Adjustable typography: An approach to enhancing low vision text accessibility. Ergonomics, 47, 469-482.

Arditi, A. (2005). Making text legible: Designing for people with partial sight. New York: Lighthouse International. Retrieved March 7, 2007, from http://www.lighthouse.org/print_leg.htm.

Arditi, A., Cagnello, R., & Jacobs, B. (1995a). Effects of aspect ratio and spacing on legibility of small letters. Investigative Ophthalmology & Visual Science, 36(Suppl.), S671.

Arditi, A., Cagnello, R., & Jacobs, B. (1995b). Letter stroke width, spacing, and legibility. Noninvasive Assessment of the Visual System Technical Digest (Washington, DC: Optical Society of America).

Arditi, A., & Cho, J. (2000). Do serifs enhance or diminish text legibility? Investigative Ophthalmology & Visual Science, 41(Suppl.), $437.

Arditi, A., & Cho, J. (2005). Serifs and font legibility. Vision Research, 45, 2926-2933.

Arditi, A., Knoblauch, K., & Grunwald, I. (1990). Reading with fixed and variable character pitch. Journal of the Optical Society of America A--Optics & Image Science, 7, 2011-2015.

Arditi, A., Liu, L., & Lynn, W. (1997). Legibility of outline and solid fonts with wide and narrow spacing. In D. Yager (Ed.), Trends in optics and photonics, series vol. 11 (pp. 52-56). Washington, DC: Optical Society of America.

Berger, C. (1944a). Stroke-width, form and horizontal spacing of numerals as determinants of the threshold of recognition I. Journal of Applied Psychology, 28, 208-231.

Berger, C. (1944b). Stroke-width, form and horizontal spacing of numerals as determinants of the threshold of recognition, II. Journal of Applied Psychology, 28, 336-346.

Campbell, K. A., Cutler, F., McDonald, R., Putt, C., Rewak, M., Strong, G., & Whitton, H. (2005). CNIB/OCAD typographic legibility research project: Clear Print report. Toronto: CNIB/OCAD Research.

Canadian Task Force on the Periodic Health Examination. (1979). The periodic health examination. Canadian Medical Association Journal, 121, 1193-1254.

Chung, S. T. (2002). The effect of letter spacing on reading speed in central and peripheral vision. Investigative Ophthalmology & Visual Science, 43, 1270-1276.

Chung, S. T., Mansfield, J. S., & Legge, G. E. (1998). Psychophysics of reading, XVIII: The effect of print size on reading speed in normal peripheral vision. Vision Research, 38, 2949-2962.

Cline, D., Hofstetter, H. W., & Griffin, J. R. (Eds.). (1997). Dictionary of visual science (4th ed., p. 521). Boston: Butterworth-Heinemann.

Colenbrander, A. (2002). Visual standards: Aspects and ranges of vision loss. Report prepared for the 29th International Congress of the International Council of Ophthalmology, Sydney, Australia.

Drummond, S. R., Drummond, R. S., & Dutton, G. N. (2004). Visual acuity and the ability of the visually impaired to read medication instructions. British Journal of Ophthalmology, 88, 1541-1542.

Estey, A., Jeremy, P., & Jones, M. (1990). Developing printed materials for patients with visual deficiencies. Journal of Ophthalmic Nursing Technology, 9, 247-249.

Eye Diseases Prevalence Research Group. (2004). Causes and prevalence of visual impairment among adults in the United States. Archives of Ophthalmology, 122, 477-485.

Garvey, P. M., Pietrucha, M. T., & Meeker, D. T. (1997). Effects of font and capitalization on legibility of guide signs (Transportation Research Record 1605, 73-79). Washington, DC: Transportation Research Board, National Research Council.

Kitchel, E. (2002). Reading, typography and low vision: A few guidelines for making large print documents and tests more accessible. Presentation. Lexington, KY: American Printing House for the Blind. Retrieved March 7, 2007, from http://education. umn.edu/nceo/Presentations/LPreading.ppt.

Kitchel, E. (2004). Large print: Guidelines for Optimal Readability and APHont: A font for low vision. Lexington, KY: American Printing House for the Blind. Retrieved March 8, 2007, from http://www.aph.org/edresearch/ lpguide.htm.

Legge, G. E., & Rubin, G. S. (1986). Psychophysics of reading IV: Wavelength effects in normal and low vision. Journal of the Optical Society of America A, 3, 40-51.

Legge, G. E., Rubin, G. S., & Luebker, A. (1987). Psychophysics of reading V: The role of contrast in normal vision. Vision Research, 27, 1165-1177.

Legge, G. E., Rubin, G. S., Pelli, D. G., & Schleske, M. M. (1985). Psychophysics of reading I: Normal vision. Vision Research, 25, 239-252.

Liu, L., & Arditi, A. (2000). Apparent string shortening concomitant with letter crowding. Vision Research, 40, 1059-1067.

Liu, L., & Arditi, A. (2001). How crowding affects letter confusion. Optometry & Vision Science, 78, 50-55.

MacKeben, M. (2000). Enhancement of peripheral letter recognition by typographic features. Visual Impairment Research, 2, 95-103.

Mansfield, J. S., Legge, G. E., & Bane, M. C. (1996). Psychophysics of reading XV: Font effects in normal and low vision. Investigative Ophthalmology & Visual Science, 37, 1492-1501.

Moriarty, S. E., & Scheiner E. C. (1984). A study of close-set text type. Journal of Applied Psychology, 69, 700-702.

Morris, R. A., Aquilante, K., Yager, D., & Bigelow, C. (2002). Serifs slow RSVP reading at very small sizes, but don't matter at larger sizes. Society for Information Display International Symposium Digest of Technical Papers, 33, 1-4.

Morris, R. A., Berry, K., Hargreaves, K. A., & Liarokapis, D. (1991). How typeface variation and typographic scaling affect readability at small sizes. In Proceedings from the 7th International Congress on Advances in Non-Impact Printing Technologies, Vol. 2 (pp. 1-9). Springfield, VA: Society for Imaging Science and Technology.

Perera, S. (2001). LPfont: An investigation into the legibility of large print typefaces. London: RNIB Scientific Research Unit. Retrieved June 4, 2007, from http://www.tiresias.org/fonts/lcfont/report/index.htm.

Rubin, G. S., & Legge, G. E. (1989). Psychophysics of reading VI: The role of contrast in low vision. Vision Research, 29, 79-91.

Smither, J. A., & Braun, C. C. (1994). Readability of prescription drug labels by older and younger adults. Journal of Clinical Psychology in Medical Settings, 1, 149-159.

Statistics Canada. (2001). Participation and Activity Limitation Survey (PALS). Retrieved February 25, 2007, from http://www.statcan.ca/ english/freepub/89-577-XIE/

Tinker M. (1963). Legibility of print. Ames: Iowa State University Press.

Whittaker, S., Rohrkaste, F., & Higgins, K. E. (1989). Optimum letter spacing for word recognition in central and eccentric fields. Noninvasive Assessment of the Visual System Technical Digest Series 7. (Washington, DC: Optical Society of America), 56-59.

Woods, R. J., Davis, K., & Scharf, L. (2005). Effects of typeface and font size on legibility for children. American Journal of Psychological Research, 1, 86-102. Retrieved June 4, 2007, from http://www.ncneese.edu/colleges/ ed/deptpsy/ajpr/voll/ajpr9.pdf.

Yager, D., Aquilante, K., & Plass, R. (1998). High and low luminance letters, acuity reserve, and font effects on reading speed. Vision Research, 38, 2527-2531.

Elizabeth Russell-Minda, M.A., research coordinator, Lawson Health Research Institute, Aging, Rehabilitation, and Geriatric Care Research Centre, Parkwood Hospital, 801 Commissioners Road East, Room B-3016, London, ON, Canada, N6C 5J1J. e-mail <erussel4@uwo.ca>. Jeffrey W. Jutai, Ph.D., associate professor and senior scientist, Lawson Health Research Institute, Aging, Rehabilitation, and Geriatric Care Research Centre; e-mail: <jjutai@uwo.ca>. J. Graham Strong, O.D., M.Sc., director, Centre for Sight Enhancement, School of Optometry, University of Waterloo, Waterloo, ON, Canada N2L 3G1; e-mail: <gstrong@sciborg.uwaterloo.ca>. Kent A. Campbell, Ph.D., director, Research Support Unit, Bloorview Research Institute, Bloorview Kids Rehab, 150 Kilgour Road, Toronto, ON, Canada M4G 1R8, and assistant professor, Department of Occupational Therapy, University of Toronto, Toronto, Canada; e-mail: <kcampbell@bloorview.ca>. Deborah Gold, Ph.D., associate director, Research Department, Canadian National Institute for the Blind ( CNIB), 1929 Bayview Avenue, Toronto, ON Canada M4G 3E8; e-mail." <deborah.gold@cnib.ca>. Lisa Pretty, B.A., manager, National Communications Department, CNIB; e-mail: <lisa.pretty@cnib.ca>. Lesley Wilmot, B.A., director, National Communications Department, CNIB; e-mail <lesley.wilmot@cnib. ca>. Address all correspondence to Dr. Jutai.
Table 1
Selected studies.

Study N Methods

(II) Arditi 4 * 9 lower-case custom
& Cho (2005) fonts varying in serif
 size (0%, 5%, and 10%).
 * RSVP and MNREAD corpus
 (computer monitor and
 paper).
 * Viewing distances at
 788.4 centimeters
 (sighted), 106 and 58.4
 centimeters (low
 vision).
(II) Arditi 40 * Font Tailor (prototype
(2004) font adjustment
 software) and Times
 New Roman, 18 to 72
 points.
 * Text viewed from 7 to
 40 inches.
(II) Arditi 4 * Times New Roman
et al. (1990) (modified, nominally
 18 point).
 * Character size varied
 by altering the viewing
 distance, range 0.165
 degrees to 1.3 degrees.
 * The participants had
 20/20 or better visual
 acuity in both eyes
 (some with lens
 correction).
(II) Chung 6 * Five modified letter
(2002) spacings.
 * RSVP method.
 * Testing at the fovea,
 5 degrees and 10
 degrees in the inferior
 visual field.
 * Critical print size
 (CPS) measured for four
 print sizes using
 standard letter
 spacing.
 * Two print sizes tested
 at 0.8 and 1.5 times
 the CPS.
 * Viewing at 200, 40,
 and 30 centimeters.
 * Times Roman
 (unmodified; monitor).
 * RSVP method.
(II) Chung 6 * Eight print sizes in
et al. (1998) central vision and
 retinal eccentricities
 of 2.5, 5, 10, 15, and
 20 degrees in the
 lower visual field.
 * Viewing at 200
 centimeters and 120
 centimeters for testing
 at the fovea and 2.5
 degrees eccentricity,
 respectively.
(II) Drummond 180 * The box for eyedrops
et al. (2004) in Arial font
 (unmodified), without
 magnification.
 * Near vision assessed
 with the usual reading
 prescription
 (eyeglasses).
(II) Estey * Hospital pamphlets in
et al. (1990) 52 12- and 14-point
 Universe medium (a
 sans serif font) or
 14-point Century
 Schoolbook (a serif
 font) typeface
 (unmodified fonts).
 * Blue, green, and black
 text.
(II) Liu & 4 * METAFONT.
Arditi (2001) * Five-letter strings
 randomly drawn (Sloan
 letters, a color
 monitor, and high
 contrast).
 * Viewed at an optical
 distance of 10 meters.
 The letter height
 ranged from 3.44 to
 4.23 arc minutes.
 * Letter confusions
 compared at wide (1.0
 letter height) and
 narrow (0.1 letter
 height) interletter
 spacings.
 * Distance corrections
 worn (n = 2).
(II) Liu & 3 * METAFONT.
Arditi (2000) * Four- and five-letter
 strings (uppercase
 letters).
 * Letter height ranging
 from 1.0 to 1.44
 centimeters, viewed at
 10 meters.
 * Distance corrections
 worn.
(II) MacKeben 6 * Arial bold (modified),
(2000) frequently confused
 letter pairs.
 * Single letters (Sloan)
 displayed 8 degrees to
 the right of the
 fovea; 36 arc minutes
 letter height.
 * Target duration
 adjusted (66-133
 minutes) for tasks
 near the threshold.
 * Binocular viewing at 91
 centimeters.
 * The participants had
 correctable refractive
 errors.
(II) Mansfield 92 * Adobe Times Roman and
et al. (1996) Courier bold
 (unmodified).
 * High-contrast MNREAD
 acuity charts.
 * Print sizes, defined
 as x-height, ranged
 from 1.3 to 0.5 logMAR
 (at a viewing distance
 of 40 centimeters).
 * The participants wore
 their usual optical
 correction for reading.
(II) Moriarty 260 * Sales brochure text set
& Scheiner in 11-point type with
(1984) 1-point leading on a
 25-pica line width,
 using Times Roman and
 Helvetica (unmodified).
(II) Morris 27 * Modified Lucida (serif
et al. (2002) and sans serif).
 * RSVP method (monitor).
 * Text had x-heights of
 40 and 160 pixels.
 * Viewed at 4 meters,
 retinal x-heights were
 about 4 and 16 points.
(II) Morris 4 * Modified 12- and 24-
et al. (1991) point fonts: "Times
 Pseudo Fixed Width,"
 "Times No Side
 Bearings," Lucida Sans,
 Lucida Typewriter, and
 METAFONT (6 and 12
 point; on a monitor).
(II) Smither & 39 (Experiment 1) * Courier, Century
Braun (1994) 34 (Experiment 2) Schoolbook, and
 Helvetica (unmodified),
 bold and Roman weights,
 and 9, 12, and 14
 points.
 * 18 medication bottles,
 and 18 hospital
 pharmacy labels (on a
 flat surface).
 * Corrective lenses worn.
(II) Yager 46 * Unmodified Dutch and
et al. (1998) Swiss at fixed x-
 height; two different
 luminance conditions.
 * RSVP (monitor); high
 contrast.
 * Reading distance 1 m:
 lowercase x-height, 8
 micromilimeters, 2.75
 arc minutes, ~5.5
 times letter acuity
 with ETDRS chart.
(VI) Campbell (over two * Adsans (sans serif),
et al. (2005) experiments) Arial, Clearview (sans
 serif), Lucida, Times
 Roman, and Verdana
 (all unmodified).
 * The participants could
 use their optical
 devices (magnifiers).
 * 16-point font printed
 on paper and
 over-the-counter drug
 inserts printed in
 7-point.
(VI) Perera 308 * Tiresias, Times, and
(2001) (total Arial, 16 point (whole
 over 5 and modified).
 experiments) * Text samples from a
 large-print book on
 paper.

Study Results

(II) Arditi The presence or
& Cho (2005) absence of serifs
 made no difference
 in the reading
 speed of all the
 participants
 (sighted and low
 vision). A small
 observed effect
 of serif size was
 found in
 Experiment 1,
 using an acuity
 criterion of
 legibility.
 Because of the
 small effect size,
 there was no
 difference in
 legibility
 between serif or
 sans serif
 typefaces.
(II) Arditi The participants
(2004) produced a
 variety of
 distinct fonts
 with Font Tailor,
 resulting in
 enhanced
 legibility (the
 gain in legibility
 averaged 75%). No
 increases in
 legibility over
 and above standard
 fonts like Times
 New Roman were
 demonstrated.
(II) Arditi For small
et al. (1990) characters, fixed
 width (FW)
 produced the
 fastest reading,
 with modified
 variable width
 (MVW) yielding
 better performance
 than variable
 width (VW)
 spacing,
 indicating
 crowding effects.
 For medium and
 large characters
 (-0.25 degrees to
 6 degrees height),
 the performance
 was best with VW,
 slowest with MVW,
 and intermediate
 with FW spacing.
 RSVP showed that
 higher text
 density was
 responsible for
 superiority at
 medium and large
 character sizes.
(II) Chung Increased letter
(2002) spacing beyond the
 standard size,
 which presumably
 decreases the
 adverse effect of
 crowding, does not
 lead to an
 increase in
 reading speed in
 central or
 peripheral vision.
(II) Chung Print size is not
et al. (1998) the limiting
 factor for maximum
 reading speed in
 peripheral vision.
 The participants
 were all sighted;
 the authors
 suggested
 extending the
 findings regarding
 the effects of
 print size on
 reading speed to
 people with low
 vision.
(II) Drummond The participants
et al. (2004) with best-
 corrected VA [less
 than or equal to]
 6/24 showed a
 significantly
 diminished ability
 to read the
 instructions on
 eyedrops bottles
 (p < .001 for
 each comparison).
 The preferred
 Arial font point
 sizes were 16 for
 the 6/24 group,
 18 for the 6/36
 group, and 22 for
 the 6/60 group.
(II) Estey 65% of the patients
et al. (1990) admitted for
 cataract surgery
 found the Universe
 (sans serif)
 14-point typeface
 the most legible,
 when reading
 samples of
 literature for
 patients. Black
 print on a white
 background was
 the preferred
 combination.
(II) Liu & Increased random
Arditi (2001) guessing and
 lateral
 interactions
 between features
 of neighboring
 letters can
 account for most
 of the
 deterioration in
 acuity observed
 under narrow-
 spacing conditions
 (using randomly
 drawn five-letter
 strings from the
 alphabet).
(II) Liu & When information
Arditi (2000) about the length
 of letter strings
 was uncertain,
 there was a
 tendency to
 underestimate the
 lengths of small,
 closely packed
 letter strings.
 The participants
 tended to omit one
 of the interior
 letters or to
 combine two
 neighboring
 letters under
 such conditions.
(II) MacKeben O[left and right
(2000) arrow]D and H[left
 and right arrow]N
 among the three
 most frequently
 confused letter
 pairs for five of
 the six
 participants. The
 most frequently
 confused letter
 pairs varied among
 the participants.
 The results
 indicated the
 possibility of
 enhancing
 eccentric viewing
 conditions by
 optimizing the
 design
 characteristics of
 the typeface.
(II) Mansfield Small, but
et al. (1996) significant,
 advantages for
 Courier over Times
 Roman in reading
 acuity, CPS, and
 reading speed for
 the participants
 with low vision.
 For the sighted
 participants, the
 differences are
 slighter, with an
 advantage in
 reading speed for
 Times. For print
 sizes close to the
 acuity limit, the
 choice of font
 could make a
 significant
 difference in
 reading
 performance.
(II) Moriarty Difference in mean
& Scheiner words read between
(1984) close-set type and
 mean words read
 set in regular
 type was
 significant for
 the effect of the
 close-set type.
 No difference in
 reading speed was
 found between the
 serif and sans
 serif typefaces.
 No significant
 effect was found
 on reading speed
 as a result of the
 interaction of
 letter spacing
 and typeface.
(II) Morris From the resulting
et al. (2002) confidence
 intervals, there
 was a performance
 advantage with
 the sans serif
 font. Results also
 suggest rendering
 serifs at small
 sizes may be
 counterproductive,
 and provide
 nothing toward
 sentence-based
 recognition with
 RSVP reading.
(II) Morris Most typographic
et al. (1991) variation has
 little or no
 effect on reading
 rates for
 characters at
 typical reading
 sizes. Crowding
 effects due to
 inadequate spacing
 are significantly
 worse for poorly
 rasterized fonts
 than for well-
 rasterized ones.
(II) Smither & When reading bottle
Braun (1994) labels, the older
 participants found
 Century Schoolbook
 in 12-point bold
 or Roman the most
 legible. For flat
 surfaces, Century
 Schoolbook and
 Helvetica, 12 or
 14 point bold,
 were best. Courier
 9 point was the
 most difficult to
 read.
(II) Yager Swiss letters were,
et al. (1998) on average, 3.3%
 wider than the
 Dutch. 16 out of
 20 participants
 read the sans
 serif font Swiss
 more rapidly than
 the Dutch (serif
 font). RSVP
 reading speed
 affected in the
 low luminance
 condition for the
 two fonts.
(VI) Campbell The results from
et al. (2005) Phase 1 indicated
 that Adsans was
 the most preferred
 font and Times
 Roman the least
 preferred. For
 Phase 2, Adsans
 was also the most
 preferred font.
(VI) Perera The participants
(2001) more legible than
 Times or Arial and
 preferred the sans
 serif typeface.
 Most preferred
 enlarged spacing,
 and legibility
 increased as the
 weight (bold)
 increased. A
 "rounded"
 punctuation shape
 and normal
 (versus enlarged)
 spacing were
 preferred.

I = randomized controlled trials, systematic reviews, or
meta-analyses; II = cohort studies or non-randomized studies
with a control; III = case control studies; IV = case series and
descriptive studies; V = expert opinion without critical appraisal
or based on physiology, bench results, or "first principles"; and
VI = unpublished gray literature.
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Author:Russell-Minda, Elizabeth; Jutai, Jeffrey W.; Strong, Graham J.; Campbell, Kent A.; Gold, Deborah; Pr
Publication:Journal of Visual Impairment & Blindness
Geographic Code:1USA
Date:Jul 1, 2007
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