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Low Vision User Requirements

From Low Vision Accessibility Task Force
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Here is the Published draft
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Status: incomplete rough first pass only!

The Category is just used to organize the aspects and are not particularly significant — and some aspects apply to multiple categories but are listed in one category for simplicity; for example, leading is listed under Reading (Spacing) yet it also helps with Tracking.

In the "User Requirement" column, "Users can..." generally indicates that a user change change a setting.

References "refs" are mostly from



User Requirement

User Perspective

Notes refs
Tracking Rewrap / One direction scrolling Blocks of text rewrap so that only one direction of scrolling is needed, e.g., for left-right and right-left languages, usually vertical scrolling and not horizontal scrolling.

For many people, it is difficult to read when they have to scroll back and forth to read a line of text. For some people with low vision, without reflow, they have to scroll several screens to read a single line of text. Additionally, the scrollbar and cursor is harder to find for some. Getting from the end of a line and finding the beginning of the next line can take considerable attention. This degrades reading flow and comprehension, sometimes significantly enough that effective reading is not possible.




TAdER scrolling



Users can set blocks of text in one continuous block, instead of in multiple columns.

For many people, it is more difficult to read when they have to scroll from the bottom of a column of text to the top of another column. For some people with low vision, with multiple columns, they have to scroll several screens to get from the bottom of one column to the top of the next. Additionally, the scrollbar and cursor is harder to find for some. Getting from the bottom of a column and finding the top of the next column can take considerable attention. This degrades reading flow and comprehension.

uaag 1.8.13 Multi-Column Text Reflow: The user can specify that recognized multi-column text blocks each be reflowed into a single column. (Level AA)

uaag 1.8.15: Linearize Content: The user can have recognized content rendered as a single column, overriding author-specified formatting of columns, tables, and positioning. (Level AA)

[Alan Smith1]


Tracking Flexible text areas with scroll bars Flexible-sized text areas automatically expand to accommodate increased text size, and shrink for smaller text. When the areas cannot be resized to accommodate all content, a scollbar is available.   @@question:  This one needs discussion.



Tracking Size text area Users can size areas with blocks of text to change the line length.

It is usually harder to read very long lines of text.

People with good visual acuity yet small field of vision might want to have small text size and small text area so they can get more characters in their field of vision.

@@question:  Any reason for setting line length to be separate from resizing text area?

uaag 1.8.8 Allow Viewport Resize:  The user can resize viewports within restrictions imposed by the platform, overriding any values specified by the author. (Level AA)

uaag 1.8.14 Ignore Fixed Unit Dimensions: The user can have the user agent override author-specified unit dimensions. (Level AA)




Users can change the justification / alignment (left, right, full/both, centered) of blocks of text.

Sometimes full justification makes reading more difficult because extra space between words causes "rivers of white", or less space between words makes it difficult to distinguish separate words. Some people find it easier to track from the end of one line to the next with full justification, and others prefer left justification (for left-to-right languages).

uaag 1.4 Provide text configuration

Luminosity and Color Luminosity overall Users can set the luminosity overall. @@SLH [@@ How much is this a hardware issue verses a content and user agent issue? It's important enough that we probably want to include it as a user requirement, even if it doesn't turn out to be a SC for content or user agent.] several

Luminosity and Color

Contrast Text

Users can change the background color and the text color.

@@SLH - clarify two different issues, really

Some people cannot read text if there is not sufficient contrast between the text and background. Some people need high contrast, including many older people who lose contrast sensitivity from ageing.

While some people need high contrast, for others — including people with some types of reading disabilities such as dyslexia — bright colors (high luminance) are not readable. They need low luminance background.

@@ need fine tuning, not just limited palette

uaag 1.4 Provide text configuration






Luminosity and Color Contrast Adjacent Users can distinguish between adjacent colors when needed for meaning.  

For example, colors next to each other in a pie chart have sufficient contrast ratio.

@@ what about colorblindness?



Perceiving (Letter Characteristics)


Users can change the text size (font size) of all text.


Including tool-tip text, pop-up text, text in maps...

uaag 1.4 Provide text configuration


[Alan Smith2]


Perceiving (Letter Characteristics)


Users can change the font face (also called font family or typeface) of all text.


uaag 1.4 Provide text configuration

Note to tool developers: When providing users a list of fonts to choose from, present the font name in the font itself — e.g., Times, Veranda, Courier — so users can tell what each font looks like.


Perceiving (Letter Characteristics)


Users can change the text style (underline, italic, bold) of blocks of text.

For some people, it is difficult to read blocks of text that is underlined or italicized. For some, bold text is easier to read.

uaag 1.4 Provide text configuration


Perceiving (Letter Characteristics)


Users can change the capitalization (all capital letters, small capital letters, sentence style) of blocks of text.

Text in all capital letters is more difficult to read for most people (with and without disabilities).

uaag 1.4 Provide text configuration


Reading (Spacing),



Users can change the line spacing / line height / leading (the space between lines in a paragraph) of blocks of text.


uaag 1.4 Provide text configuration



Reading (Spacing)

Letter spacing

Users can change the letter spacing (space between letters/characters) of blocks of text.

  uaag 1.4 Provide text configuration TAdER

Reading (Spacing)

Word spacing

Users can change the word spacing (space between words) of blocks of text.


uaag 1.4 Provide text configuration


Reading (Spacing)

Element spacing

Users can change the space between elements (e.g., space between paragraphs, or space above headings) for blocks of text.

Having additional space between elements helps most people group information. For example, having more space above a heading and less space below it, helps associate the heading with the text below.

@@question: Is this the same as element-level customization, or separate? TAdER element

Reading (Spacing)


Users can change the margins (blank space around blocks of text) around blocks of text.

Having wide margins around blocks of text helps focus on the text and not get distracted by surround text, images, etc.

uaag 1.4 Provide text configuration TAdER


Element-level customization

Users can customize text differently for specific elements, such as headings, lists, and paragraph text.

For example, some people who need large text set headings to be smaller.

  TAdER element


Proportional text increase

Users can choose whether or not all text increases proportionally; for example, headings remain bigger than main paragraph text.


uaag 1.4 Provide text configuration TAdER



Users can set borders around blocks of text — including border line color, width, style.

Some people prefer to use borders to indicate headings, rather than have them much larger than the main text.

uaag 1.4 Provide text configuration




Users can change indentation (e.g., space in front of list items, the first line of a paragraph) for blocks of text and specific elements.




Users can turn hyphenation on or off (word breaks; when a long word is at the end of a line, either separating the word with a hyphen, or putting the whole word on the next line).

For some people it is especially difficult to understand words that are hyphenated. While primarily a cognitive issue, it becomes more of an issue when text size is increased, thus it is also related to low vision. Some people with very large text may prefer hyphenation so there is less wasted space at the end of lines.

uaag 1.4 Provide text configuration



Printing customized text

Users can print text after customizing it.

It is difficult for some people to read text on the computer; they need to be able to print electronic text on paper in order to read it.

uaag 1.4.4 Configured and Reflowed Text Printing... (Level AA)

[Alan Smith4]

TAdER printing

  User style sheets Users can configure user stylesheets   @@ more details in: uaag css  
  Zoom Users can rescale content within top-level graphical viewports   uaag 1.8.5  
  Point of regard The point of regard remains visible within the viewport when the viewport is resized, when content is zoomed or scaled, or when content formatting is changed.   uaag 1.8.6 [Erich1]
    @@ Help users to orient within, and control, windows and viewports   @@ more details in:
uaag gl viewport
Proximity   Related information is in close proximity. People with limited field of vision or screen magnification will have little in their field of view at one time. For example: labels and controls, or matching tests in two columns


Proximity Feedback Feedback is in close proximity to the user's visual focus. People with limited field of vision or screen magnification won't see things that are not near their focus.

@@ expand to dialog boxes?

[is this covered sufficiently?: Fleeting messages that appear and then disappear that may appear outside the user's zoomed or magnified viewport. Currently would likely fail SC 2.2.1]

  Users agent functionality Browser or other user agent functionality is not disabled.     [Laura3]

Users are informed of links that open in a new browser tab.

People with limited field of vision or screen magnification may not see if a new tab is opened.   [Laura4]
    Users cursor does not obscure tool-tip text. Some people use larger cursors so they can see them. [Is this a screen magnification software issue?] [Laura5]
  Pop-ups Users can access information in pop-ups.  

Use case: Screen magnification user hovers over image, acronym, or other thing with pop-up. The pop-up. is larger than their view. When user scrolls to read it, it loses focus and disappears. Hover behavior results in a change of context for your point of regard.

[Bruce Bailey1; JimA3]


  Background images

Users can choose whether or not to hide background images.


Images providing useful content are not coded as CSS background.


@@question: See CSS background images and HCM e-mail thread


Other issues not (yet) included in above:

  • TAGLINE: Clashing high contrast and bright images
    1. GROUP: Excess Brightness / Color Customization
    2. SUMMARY: High contrast (light on dark) may clash jarringly with bright images.
    3. DESCRIPTION: A person using high contrast may experience difficulty accessing important content visually on a page if the content is placed near a decorative, non-essential element, like a picture or graphic, if these things render brightly in high contrast. @@ very similar to [Erich2]. [Erich4]
  • TAGLINE: HCM - Problems with photographic images
    1. GROUP: Color Accessibility Support
    2. SUMMARY: Some inverted high contrast color schemes render photographic images as photo negatives.
    3. DESCRIPTION: A person using high contrast mode (HCM) which inverts colors is trying to view shared images of friends on social media but losing content & context because photographic images are also displayed with inverted colors. [Erich2]
  • Icon fonts that when combined with custom fonts are browser/AT combinations like ZoomText and Firefox change to squares and are unrecognizable. Discussed in 28 Oct telecon. Maybe issue for everyone and not sufficiently more of an issue for people with low vision?
  • Not for this list, but for understanding low vision users: Person wants to use mobile OS magnification. [John Rochford1], Person using TTS, not a screen reader. [John Rochford2]