What do you mean by low-vision? What medical conditions or environmental conditions are you trying to overcome? Is this for signage, advertising, a book?

Cheers, Si

I'm not an expert, but I think low vision refers to people who are not legally blind, but have difficulty discriminating fine details, like text. I would also be interested to include in this discussion which typefaces may be accessible to people as they reach their older years—baby boomers, etc— who reach for their magnifying glasses each time they sit down to read something.

Poppl Laudatio is very readable for people with impaired vision (I should know -- I'm one prescription away from being legally blind without my glasses), even at sizes as small as 10 pt.

wouldn't size be the critical element here? Moreso than the specific face?

speaking of bigger type, Penguin books is redoing their paperbacks in bigger sizes:

http://www.theledger.com/apps/pbcs.dll/article?AID=/20050812/ZNYT01/5081...

...

Where can I see an example of ClearviewADA? Also, can you tell me where I can get a copy of the guidelines from the Americans with Disability Act that you mentioned?

You can get info on ADA on the Department of Labor web site, or you can go to SEGD and buy their white paper for $20. (I recommend the white paper)

http://www.segd.org/resources/publications.html

As to ClearviewADA samples, send me a private e-mail, and I'll send you a pdf sample

Specifically we are talking about elderly people and the partially blind. We are also concerned with people that have learning disabilities, have dyslexia, or may be new to the Rnglish language or roman alphabet. The project is a traveling exhibition - so it would be signage and large format graphic panels.

-r

Just a note - the SEGD paper is from 1992 - I emailed them today asking if there was an update. They responded saying the fed's have released new recommendations, but have not signed them into law. So, perhaps ADA is more "current".

Sadly, there hasn't been a lot of good research into which typefaces and sizes are best for low vision. However, the research that does exist suggests that type size and text design choices are more critical than the typeface choice. Considering issues of colour contrast, line length, leading, and —because this is an exhibition— placement of text in the environment will make a larger difference to a reader than choosing Plantin over Minion.

Granted, one should use a reasonable typeface for the job. Here the research that is available suggests choosing a typeface that is well spaced and on the slightly heavier side. The ADA and SEGD guidelines can help here to weed out typefaces that are too light. Doing some informal user testing will also help, especially when choosing a type-size and colour combinations.

There aren't a lot of good studies to recommend on this subject: I've looked at a lot of the research (I can give you my bibliography if you're interested) and have concluded that a lot more research needs to be done, especially research geared to giving good guidelines to working designers.

I can suggest reading Alison Shaw's Print for partial sight. It is getting dated, but it is the best study of typeface and type size for low vision. This isn't to say that it is perfect, but it is the most comprehensive study to date. You could also look at the research of the Minnesota Laboratory for Low-Vision Research. It's some of the best work being done currently, but it is aimed at optometrists. Lastly, Zoe L. Strickler has done some interesting research (published in Visible Language) in designing interactive systems for older adults and low vision. Though it is about interaction design, it does say a lot about design in general for low vision and older adults.

Hope that helps, and isn't too much.

References
Shaw, A. (1969). Print for partial sight: a report to the Library Association Sub-Committee on Books for Readers with Defective Sight. London, Library Association.

Strickler, Z., & Neafsey, P. J. (2002) Visual design of interactive software for older adults: Preventing drug interactions in older adults. Visible Language. 36(1), 4-28.

I think "low-vision" and visual acuity of aging adults (ouch!) are issues that can be clearly (ouch again) addressed with research and studies related to type sizes and letterform, as you are involved with.

I believe your mention of learning disabilities (inclusive of dyslexia, dyscalculia, dysgraphia, dyspraxia, and visual processing disorder) involves a completely different area of research not fully dependent on character recognition itself.

By no means do I understand the issues related to such disorders, but one of my business partners is heavily involved with Edvocacy.org, a not-for-profit organization dedicated to establishing a national early recognition program for children with dyslexia. (Visit the link and take the little decoding test to give you a sense of what dyslexic readers go through.)

My wife also happens to work for The Landmark School which is one of the best known private educational facilities for children with reading and learning disorders. Of what I know of their mission is that they are training the students to decode and reprocess information encountered in their daily lives.

Through my wife, I have recently contacted Landmark to see if I could participate in or contribute to the school's art program (all of their teachers are required to have Masters in Special Education). I have been toying with the idea of letterform collages, innovative calligraphy and found object alphabets (inspired by both Nick Shinn and Clotilde Olyff). In that way it would just be the joy of shapes and recognized individual forms as art, and not for reading comprehension.

So many ideas, so little time... (at least another 50 years I hope).

Depending on your tolerance for idiosyncracy, you might have a look at my font Freight Micro. Although it's primarily meant for the screen (Jeffrey Zeldman has quipped that it stays crispy in milk), it's an indirect by-product of the fact that early-onset low vision runs in my family.

Placement, type sizes, lighting, distances, are all variables that need as much attention as typeface choice in an exhibit design. I assume the type is used at display sizes?

Since the lighting in a traveling exhibit is an uncontrolled variable, you'll need to ensure contrast between type and background. Choose colors for both with plenty of contrast.

Terry B. recommended to me the fine book "Wayfinding: People, Signs and Architecture", which deals with more general issues of clear wayfinding. Those ideas are useful in an exhibit context, I think.

You may find useful some information here http://www.tiresias.org/index.htm

This site is for professionals who work in the field of visual disabilities and for all people who have an interest in solving the problems faced by people with disabilities. Guidelines on accessibility issues for all types of disabilities are also on this site.

There is also a specially designed family of fonts.

Richard

There definitely is very little information regarding what you're looking for. So far all have made good recommendations. As Carl pointed out, the Wayfinding book is about the only hard copy I've ever gotten my hands on that seriously focuses on clear type for environments.

Roger, if you haven't already make sure you contact James about Clearview ADA, I've had the opportunity to see it and so far James has been one of the few people I've known who has put the time in to really address type for people with low-vision. This has been a subject I've been heavily involved in attempting to solve as well. Good luck!

Hello everyone:

I am also interested in finding out a bit more on this subject, more specifically about typefaces for older adults (seniors 65+). Which are more appropriate? What sizes? How much leading? Column width?... These are some of the questions that are arising...

After a somewhat extensive search online, I couldn't find any relevant information, or resources... I mean, from the type design perspective...

Tiresias (http://www.tiresias.org/) and APH (http://www.aph.org/) both have typefaces they say are appropriate for low vision readers, but I find the overall quality pretty doubtful. Also, I don't know who their designers were, and I haven't seen any credible results published...

W3C (http://www.w3.org/), AARP (http://www.aarp.org/) and AGElight (http://www.agelight.com/) have all published some guidelines, but only agree on the use of sans serif typefaces, from ~12 pt upwards...

Irene Strizver (2004) also recommends some type settings, but doesn't provide any definitive answer.

Can someone help me find more information, or fonts with enough documentation on this?

I would prefer 100,000 people with low vision viewing my flash site to one iphone user.

robot_type "...so it would be signage and large format graphic panels. "

That's great! Size is a huge thing to all your reading groups.

And Clearview is a great choice for road signage, (your link is broken JM?) but these reading groups are not any different from "normal" people in that the typeface choice should compliment the topic of the content, perhaps within narrower bounds than a normal reading group, but the selection should not be entirely based on either "readability" or .gov, IMHO.

So... what are the signage and large format graphic panels about?

David:

I also don't know which or how to apply the "large format" factors... It seems to me that common sense and much testing is needed. But how to do it?.

For seniors (older adults) current recommendations vary... The common denominator seems to be to recommend the use sans serif typefaces in large sizes (e.g.: type for reading on screen ~14pt). I can't imagine what to do in large format graphic panels (and here ADA can provide some guidelines). Although it seems to contradict the maxim of "we read best what we read more", I think the sans serif recommendation is due to the fact that sans serif typefaces may help increase the white space and avoid unnecessary visual clutter (without dismissing the serifs' function, though).

Although older adults aren't necessarily people with disabilities, low vision, speed of reading and cognition problems come with age (and yes... many of us will suffer from most of these!):

"Of people aged ≥ 70 years, 18% report blindness in 1 or both eyes or some other trouble seeing, 33.2% report problems with hearing, and 8.6% report problems with both hearing and seeing.1 Precisely because these experiences are so common, they are often overlooked or dismissed.2 Moreover, normal age-related changes in hearing and vision may be con- fused with abnormal sensory changes that can compromise function. Likewise, abnormal changes due to eye and ear pathology may be confused with normal age-related sensory changes."
http://ajph.aphapublications.org/doi/pdf/10.2105/AJPH.94.5.823

And it's not exclusive to US Older Adults. It's more or less the same everywhere.

I couldn't find much information on the Clearview Typeface specification/reports/Designer(s) (other than Wikipedia: http://en.wikipedia.org/wiki/Clearview_%28typeface%29), but I found an interesting read on Chpater 7 of ADA's 2010 Specifications: http://www.ada.gov/regs2010/2010ADAStandards/2010ADAStandards.pdf

"703 Signs
703.1 General. Signs shall comply with 703. Where both visual and tactile characters are required,
either one sign with both visual and tactile characters, or two separate signs, one with visual, and one
with tactile characters, shall be provided.
703.2 Raised Characters. Raised characters shall comply with 703.2 and shall be duplicated in braille
complying with 703.3. Raised characters shall be installed in accordance with 703.4.
703.2.1 Depth. Raised characters shall be 1/32 inch (0.8 mm) minimum above their background.
703.2.2 Case. Characters shall be uppercase.
703.2.3 Style. Characters shall be sans serif. Characters shall not be italic, oblique, script, highly
decorative, or of other unusual forms.
703.2.4 Character Proportions. Characters shall be selected from fonts where the width of the
uppercase letter “O” is 55 percent minimum and 110 percent maximum of the height of the
uppercase letter “I”.
703.2.5 Character Height. Character height measured vertically from the baseline of the character
shall be 5/8 inch (16 mm) minimum and 2 inches (51 mm) maximum based on the height of the
uppercase letter “I”
703.2.6 Stroke Thickness. Stroke thickness of the uppercase letter “I” shall be 15 percent
maximum of the height of the character.
703.2.7 Character Spacing. Character spacing shall be measured between the two closest points
of adjacent raised characters within a message, excluding word spaces. Where characters have
rectangular cross sections, spacing between individual raised characters shall be 1/8 inch (3.2 mm)
minimum and 4 times the raised character stroke width maximum. Where characters have other
cross sections, spacing between individual raised characters shall be 1/16 inch (1.6 mm) minimum
and 4 times the raised character stroke width maximum at the base of the cross sections, and 1/8
inch (3.2 mm) minimum and 4 times the raised character stroke width maximum at the top of the
cross sections. Characters shall be separated from raised borders and decorative elements 3/8 inch
(9.5 mm) minimum.
703.2.8 Line Spacing. Spacing between the baselines of separate lines of raised characters within
a message shall be 135 percent minimum and 170 percent maximum of the raised character height."

Ok. Once again, sans serif is the type selection of choice.

Although I find hard to agree, ADA even provides character proportions, body size, line height and different spacing settings. but wait a second... uppercase characters? And doesn't different character drawings of structure/stroke/modulation/contrast imply different settings?...

This is all starting to look like a huge mess to me... So I agree with you... Maybe the .gov is "too narrow" of a selection for a more general purpose group... Maybe we should try to evaluate what the readability and legibility is for each situation? How to do it?

BTW: Where can I find out more on Clearview?

Just found this one: http://www.aiga.org/typography-and-the-aging-eye/
It proposes methods to simulate low-vision testing...

Here some results of comparative testing of Tiresias, Verdana, Clearview, etc.: http://www.aerbvi.org/modules.php?name=AvantGo&file=print&sid=1637

More results on comparing serif to sans serif: http://findarticles.com/p/articles/mi_6836/is_7_101/ai_n28446295/pg_5/

Thanks for the links and informations ^^
Its helping me a lot ;)

Finally found some more information on Clearview Type System: http://clearviewhwy.com/ResearchAndDesign/researchWhitepapers.php

It seems to have been designed by Donald Meeker and James Montalbano. Of the three typefaces I've encountered, designed specifically for low vision conditions (Tiresias, APHont) and stress conditions (Clearview), this is the only one to have been designed by professional Designers and improved/finished by a Type Designer, and to have been properly (and scientifically?) tested.

There is no information about the Tiresias typefaces' designer, and the development team claims to have tested the Tiresias Typeface. But they only provide (an useful) checklist: http://www.tiresias.org/research/guidelines/checklists/fonts_checklist.htm. Neverthless, I can't seem to find any published results.

As with Russel-Minda et al. (http://findarticles.com/p/articles/mi_6836/is_7_101/ai_n28446295/pg_8/) I couldn't find any published results for APHont's use, although they do publish some guidelines online... Once again, no information about the designer...

It seems that legibility (and readability) is still a very confusing and an ill documented area of Graphic and Type Design. Especially regarding user testing... Most of the more interesting papers published (at least regarding the testing methodology) are from people who really don't seem to have a clue about well designed type shapes.

I encourage you to take a look at one of the most relevant (?) authors I found as an example: http://www.ncbi.nlm.nih.gov/pubmed/16099015.

Tell me what you think of this...

Regarding the previous comment I made:

I think the sans serif recommendation is due to the fact that sans serif typefaces may help increase the white space and avoid unnecessary visual clutter (without dismissing the serifs' function, though).

The authors Russel-Minda et al. and Arditi mentioned above provide some interesting explanations...

It seems that legibility (and readability) is still a very confusing and an ill documented area of Graphic and Type Design.

Because it's like E. B. Huey said, back in 1908:
"And so to completely analyze what we do when we read would almost be the acme of a psychologist's achievements, for it would be to describe very many of the most intricate workings of the human mind, as well as to unravel the tangled story of the most remarkable specific performance that civilization has learned in all its history."

For a good number of years now we've had a highly qualified research psychologist working for a filthy-rich corporation that actually seems to care about reading, but we're still largely in the dark.

See also: http://typophile.com/node/1323#comment-10544

hhp

See also:

Canadian Department of Heritage (1994). Access series: design guidelines for media accessibility. (Cat. No. R64-182/5-1993E)

Mansfield, S., Legge, G. E. and Bane, M. C. (1996). Psychophysics of Reading. XV: Font Effects in Normal and Low Vision. Investigative Ophthalmology & Visual Science, (37)8. 1492–1501.

And if you are interested in reading and dyslexia, my past supervisor wrote the book on it:

Klein, R. & McMullen, P. (1999). Converging Methods for Understanding Reading and Dyslexia. Cambridge. MIT Press

A quick database search through my university gave me a tremendous amount of results, but you’d need database access to get at the the articles. At the bottom of the abstract page of the Mansfield (1996) article there some good references that cite it. I haven’t read Mansfield, so I can’t tell you if the science sucks or not, but it has been my experience that in science and typography research land, the work that has been done is thin, and mostly crappy.

You might find a few interesting references in the literature section of my website:

http://readthetype.com/literature/

Choosing a typeface and designing a page layout with type spec has very little to do with science.

The best way to find what’s appropriate for a particular market, demographic, tranche or whatever of the population is to study the present practice in that area, or, if you are not the designer, hire someone with the appropriate experience.

For low vision readers, the trick is to make the type large while retaining a certain amount of grace in the layout.

The best way to find what’s appropriate for a particular market, demographic, tranche or whatever of the population is to study the present practice in that area

But then all you're doing is further entrenching the status quo (which too often is based on other people's -often bad- taste). Although it's not enough by itself, science can play a role in anything (even mixing paint for abstract art). And it's great at dispelling intuitive assumptions like "the type should be large"; there are many flavors of "low-vision" and one needs to learn the science behind them to be a good designer.

Science is not about universities or lab equipment. Science is about an attitude - an attitude central to Design.

hhp

Christopher:
Thank you for the references and your input on this. I can really relate to it!... I've already added your website to my reading list ;)
——

Nick:
Let me agree and disagree. When you have a design brief, sure you have to make and educated, aesthetic-based decision. We do it all the time. We evaluate the client and research the target audience, we evaluate and research the contents and we prototype the design. We can even test the result sometimes. I'm with Hrant this time: sure this is not a laboratory, but this uses a very similar process, don't you agree?

Many, many factors taken into account in this process are also some kind of science. You know that choosing a typeface will change the reading speed, the white space, the copy structure/hierarchy, etc... If you do it more intuitively, or more scientifically... well I thinks its up to each one of us.

For low vision readers, the trick is to make the type large while retaining a certain amount of grace in the layout.

Couldn't agree more! See below my first attempt to try to compile a recommendation list.

——
About these papers/researches, I keep struggling with some things like the methods and results they provide. Some are really contradictory to my experience/design education. For example, quoting the abstract from Psychophysics of Reading:

Data were collected using versions of the MNREAD Acuity Chart printed with the Times (proportionally spaced) and Courier (fixed-width) fonts.

With this, they cant test vision acuity (AKA legibility?) regarding the selected typeface (no doubt here). But they provide reading speed results... also with a MNREAD chart? Of course they found something we already know for users with normal vision:

Maximum reading speeds for normal subjects were 5% faster with Times than with Courier (P < 0.001), but for subjects with low vision, maximum reading speeds were 10% slower with Times than with Courier (P < 0.05). [...] For normal subjects, the differences are slighter, with an advantage in reading speed for Times. However, for print sizes close to the acuity limit, choice of font could make a significant difference in both normal and low-vision reading performance.

My problem with these is that they fail to present the samples used for testing. This is a matter also raised by Albert Jan-Pool at ATypI in Dublin during one presentation.

And, whenever they provide them, the testing materials are poorly designed. No wonder the results are what they are... remember this one: http://web.princeton.edu/sites/opplab/papers/Diemand-Yauman_Oppenheimer_...

Let me try to compile a starters list with the recommendations based on the literature below (for seniors/older adults):

1. Typeface:
   1a) sans serif;
   1b) legible: high x-height, wide horizontal proportions, pronounced extenders, pronounced/disctinct finishing strokes and crossbars, open counters, consistent low modulation strokes, distinct glyph set (*1);
   1c) large body (*2);
   1d) use the minimum number of fonts possible;
   1e) roman-regular type style (*8);
   1f) avoid decoration (*6);
   1g) Use of Sentence or Mixed Case forms;
2. Spacing and alignment (in comparison to normal vision reader materials);
   2a) wider letter spacing;
   2b) increased line height;
   2c) increased spacing on images, graphics and page layout elements (gutters, margins, etc) (*3);
   2d) Left-hand alignment;
3. Structure of the text:
   3a) clear contrast between structure/functions like headings, subheadings, lead, body, captions, etc (*7);
   3b) smaller, or more separated units of text (*4) (*8);
   3c) use structures like bullet lists, or boxes to highlight, or separate (*8);
4. Color:
   4a) bright, avoiding low saturation, or vibrant (*5);
   4b) dark on light (AKA, black type on white backgrounds);
   4c) avoid reverse outs and background patterns;

The problem is that this is an interdependent variable system... Some of these are really simple science/lab tested result based decisions (like 1a). Others... well...

——
Notes:

(*1) We know what is constitutes a legible typeface (see the literature here, or start with this one: http://www.aiga.org/typography-and-the-aging-eye/. But what should we use and how to test the different selected options on a screen prototype? APHont, or Tiresias seem like viable candidates, but really, Verdana is a time tested, master designed typeface.

(*2) For print sizes, recommendations vary a bit, but seem to be between 12 and 14 pt for body size. On screen, what should we use?

(*3) Agelight proposes: "It is suggested you leave a wide margin of 1 1⁄2 or more inches on the right side of the page to maximize usability with different monitor types, window sizes and display resolutions."
It's a bit outdated...

(*4) Agelight proposes: "Short pages, those containing one or two screens of text, work well for the homepage and menu pages when users are scanning for informational links. Longer pages, although they require more scrolling, may work well for destination pages where related content can be printed and read/scanned together. Avoid creating large pages with multiple articles and links. Break topics down into succinct pages for usability and printing."

(*5) Agelight proposes: "bright, fluorescence or vibrant can have edges that appear to blur and create after-images,which fatigue the eye [...] the safest colors to use are black, white, blue and yellow where as red, green brown, grey and purple can be troublesome.

(*6) From Agelight: "Drop shadows on text, often used to give words the appearance of depth, can be difficult to decipher."

(*7) Agelight & Strizver recommend body size between 12 and 14 pt. Agelight recommends titles two points larger, but I disagree. Type should be CLEARLY contrasting in size, using a rule of thumb to have a 4 pt difference step, or a 10-20% difference in size (depending on typeface and body selected).

(*8) From Agelight: "Limiting the use of bold to emphasize a title or a key word is recommended.". Condensed / expanded are also not recommendable. Strivzer also adds: "Use boldface to emphasize a word or a small group of words. Keep use of italics to a minimum; research indicates that italic type is 18 percent more difficult to read than Roman (upright) letters."

——
References:
2001 - AGELIGHT - Interface design guidelines for users of all ages
2001 - Bernard - Liao - Mills - font type size affect reading time
2004 - Strizver - 26FYTIDesigningforSeniorsITC
2004 - University of Washington - Low Vision FAQ
2005 - AARP - Designing Web Sites for Older Adults - Heuristics
2005 - Arditi - Serifs and font legibility
2006 - Nini - AIGA - Typography and the Aging Eye- Typeface Legibility for Older Viewers with Vision Problems
2007 - Russell-Minda et al. - The legibility of typefaces for readers with low vision - a research review
2007 - Yaffa - The Road to Clarity
2008 - W3C - Web Accessibility for Older Users - A Literature Review
2009 - Tiresias - Fonts checklist
2009 - Tiresias - How to make fonts and typefaces accessible for people with disabilities
2009 - Tiresias - Typefaces and legibility
2010 - ADA Standards (Chapter 7)

P..S.: Sorry Christopher... still haven't gone through your reference list, but will soon!

That’s OK, it’s not going anywhere, but it does get updated from time to time. I’ll tweet when I do. — @Readthetype

And another trick to help you in your lit-review is to start with a new article, preferably from a relevant journal with a high impact factor, go to its references section, and see what articles it references and go from there (back in time). Conversely, if you use Web of Science as your database of choice, there is a link on bottom to create forward and backward citation maps (which tend to be somewhat flaky) and a “times cited” link at the top of the article which will give you a complete list of all articles that have cited the one you are looking at since its time of publication (forward in time). By using this method, you can attack your subject from two sides at once.

We can even test the result sometimes. I'm with Hrant this time: sure this is not a laboratory, but this uses a very similar process, don't you agree?

Certainly, if you’re designing for special needs readers, it helps to know something about those needs, which can be quite varied.

Nonetheless, I consider the marketplace to be an empirical proving ground for what is functional. It’s true, as Hrant points out, that a lot of garbage gets foisted on the public, but ultimately people will read what works best for them, and publishers facilitate that or they are out of business—although well-meaning governments can provide a bad skew by financing wishful thinking.

**

Pedro, I put it to you that even your most basic “scientifically-proven” precept is incorrect. Do you really think that the Old Nicks of this world (of whom I am one) will take kindly to reading books set in sans serif, when we have been reading them set in serifed fonts all our lives? I’m not familiar with libararies in Portugal, but those I have been into elsewhere have large print sections where all the books are set in classic serifed faces. Doesn’t this suggest there is some merit in the practice?

What happens when you age is that you have to view the text from further away, because you can no longer focus as close as you once could. This reduces type size to below the optimum arc of vision, therefore it needs to be bigger to compensate. It’s that simple! Many people slide their glasses down their nose to bring the type into focus (it’s human nature to “make do” rather than get new glasses)—but that makes the type smaller, again, not enough arc of vision.

There is also some loss of contrast due to yellowing of the lens.

I’m talking about the normal deterioration of vision brought about by aging.

people will read what works best for them

People will read the content they either want to or have to read. The degree of motivation is inversely proportional to how good the typography needs to be to enable the completion of the reading task. Our job is to make the typography functional whether we can get away with doing a crappy job or not (and from all appearances frankly we can get away with quite a bit). I wish poor typography was a good predictor of failure!

hhp

@pedamado: “No wonder the results are what they are... remember this one: Diemand-Yauman et al. (2010).

Just curious. For the sake of discussion, what are your thoughts on this study?

In looking at this topic, I had thought that the concern was to find a typeface for people with a severe visual impairment, possibly legally blind.

For that, I would have thought the face would need to be very bold, all caps, and with the stems of the letters having an unusual shape - flared, for example, or the opposite; having the whitespace pointing inwards where lines join and the stems otherwise rounded and bulging in appearance.

I don't recall encountering a typeface of this kind.

Why would you have made each of those assumptions?

> more specifically about typefaces for older adults
> (seniors 65+). Which are more appropriate? What sizes?

Seems to me that you're lumping together a very broad range of users. Vision obviously changes as we get older, but it's still extremely variable. My 90-year-old mother still reads standard books and magazines without difficulty, but she has a friend in her 70s with macular degeneration who is almost blind. There's not going to be a point size recommendation that's appropriate for everyone over 65.

I'm all for research in this area, although I think many of the findings are largely common sense (use an easy-to-read font, bump up the point size, etc.).

Not sure if this will be of any help to you, but some computer companies may have done some research on readability on monitors for folks with disabilities. For example, Apple has a page discussing some special computer settings for users with poor eyesight. Not a lot of info, but it's interesting that they have settings for making the screen high contrast and the option to reverse black and white. (I'm not even sure why reversed type would be easier for some with impaired vision to read, but apparently it is in some cases.)
http://www.apple.com/accessibility/macosx/vision.html

@Thomas Phinney:
Why would you have made each of those assumptions?

A fair question.

I'll start with the one that's the easiest to defend.

Very bold.

For printing to be legible at the lowest possible optical resolution, you have to maximize the total information content relative to feature size.

Which leads to the conclusion that, on average, approximately 50% of the paper should be covered by ink.

Bulging stems, flared corners, otherwise weird-looking?

I'm assuming this font, to be usable for people with a severe visual impairment, is going to be designed so that it would be legible to people with normal vision in a two-point size.

So I'm envisaging that somehow it is going to be designed to compensate for being blurred. The techniques I'm thinking of are similar to ones used in the design of masks for the photolithography of integrated circuits so that features appear to be neater and more rectangular than seems to be possible given diffraction-limited resolution of the wavelength of light used.

But why all caps?

Very bold.

For printing to be legible at the lowest possible optical resolution, you have to maximize the total information content relative to feature size.

Which leads to the conclusion that, on average, approximately 50% of the paper should be covered by ink.

informaton ≠ ink
Most often than not, bold is less legible than regular. Especially at low resolution.

All caps is harder to read. If it's just a few words it's not a big deal, but setting sentences in all caps reduces readability.

@JamesM:
All caps is harder to read. If it's just a few words it's not a big deal, but setting sentences in all caps reduces readability.

I'm aware of that. The term "low vision" has a specific meaning, and I have taken it to refer to people with so profoundly impared vision that it is no longer practical to concern oneself with readability, and even achieving legibility will require every resource at our command.

@riccard0:
informaton ≠ ink

Yes. You'll note I said 50% and not, say, 80%.

The information content of a page at any given level of maximum resolution, assuming only the two colors of black and white may be used, indeed does reach a maximum when ink coverage is at 50%.

This is basically for the same reason that if you have identical checkers of two colors, and you arrange them in a row, there are more possible arrangements of nine red checkers and nine black checkers than there are of six red checkers and twelve black checkers.

Information does not equal ink. In this context, it equals the difference between where the ink is and where the ink is not.

Thanks, Quadibloc, for explaining your thinking. I appreciate that you took my question in the spirit it was intended. :)

I expect that for the extreme end of low vision, the ideal choices are different than they are for the majority of low vision cases. It's also an important question as to whether the text in question will *also* be read by others, or only by the vison-impaired or massively vision-impaired.

If someone's vision is so bad that they must decipher one character at a time, they'll probably stop reading except perhaps for things that are extremely short, like a label or a note consisting of a few words.

A friend of mine went virtually blind from macular degeneration. In the early stages she could get by with large-type books, magnifying lenses, etc., but after a certain point it became impractical and started using books on tape or asking a relative to read to her.