Difference between revisions of "Low Vision"

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Low vision describes any number of situations where a person has lost a significant amount of their vision, but not enough to be considered blind. It can be caused by any of a number of factors, each of which presents as a slightly different set of visual challenges. These include:
For information about low vision, visit [https://accessibility.perpendicularangel.com/what-is-accessibility/types-of-disabilities/visual-disabilities/low-vision/ Low Vision] on [[Perpendicular Angel]].
 
* albinism
* brain injuries
* cataracts
* diabetic retinopathy
* eye injuries
* eye cancer
* glaucoma
* hemianopia
* macular degeneration
* retinitis pigmentosa
* retinal detachments
* various infections
 
==Design Considerations==
 
People with low vision may rely on the browser's zoom features, or they may use screen magnification software such as [[ZoomText]] or [[MAGic]], which show a small portion of the screen at a time. Low vision users are also often [http://kb.perpendicularangel.com/index.php?title=Category:Vision_issues#Screen_readers screen reader users] so keep those requirements in mind as well.
 
When designing for users with low vision, we need to:
 
* Use good contrasts and a readable font size. Ensure that your software passes [[WCAG Guideline 1.4.3 Contrast (Minimum)]]
* Publish all information on web pages (HTML), not PDFs or other inflexible formats
* Use a combination of color, shapes, and text
* Follow a linear, logical layout and ensure text flows and is visible when text is magnified to 200%
* Put buttons and notifications in context.
* Provide a visible focus state. Ensure that your software passes [[WCAG Guideline 2.4.7 Focus Visible]]
* Provide a clear visual distinction between content (text, images) and controls (buttons, links, etc.)
 
We need to avoid:
 
* Disabling pinch-to-zoom
* Using low color contrasts and small font sizes
* Burying information in downloads
* Only using color to convey meaning
* Spreading content all over a page and forcing a user to scroll horizontally when text is magnified to 200%
* Separating actions from their context
 
Sources for list above:
* [https://accessibility.blog.gov.uk/2016/09/02/dos-and-donts-on-designing-for-accessibility/ Dos and Don'ts on designing for accessibility] and the accompanying poster on [https://accessibility.blog.gov.uk/wp-content/uploads/sites/52/2016/09/visually-impaired-low-vision.png designing for users with low vision (PNG)] by [[Karwai Pun]] at the [[UK Accessibility in Government Blog]]
* [[Deque University]] accessibility training
 
[https://www.invisionapp.com/blog/mobile-design-visually-impaired/ How to design mobile app experiences for the visually impaired] by [[Ayesha Zafar]] on [[Invision]] discusses steps specific to mobile interactions.
 
==Tools==
 
* [http://www.amd.org/what-is-macular-degeneration/experience-what-amd-looks-like/ Macular Degeneration] simulator and video
* [https://www.aao.org/eye-health/diseases/glaucoma-vision-simulator Glaucoma simulator]
* [http://www.cnib.ca/en/your-eyes/eye-conditions/eye-connect/Pages/EyeSimulator.aspx#diabetic-retinopathy Simulator for Macular Degeneration, Diabetic Retinopathy, Cataracts, and Glaucoma]
* [http://webaim.org/resources/contrastchecker/ WebAIM's Color Contrast Checker] - will tell you if two colors you enter pass accessibility guidelines
 
===ZoomText examples===
Introduction to ZoomText and Screen Magnifiers, with captions.
<YouTube>https://www.youtube.com/watch?v=ojtiVj78QPw</YouTube>
 
Leanne Clough illustrates the benefits of ZoomText. Transcript in the comments below [[https://vimeo.com/13757711 the video on Vimeo's site]].
<vimeo>https://vimeo.com/13757711</vimeo>
 
==Additional resources==
 
* [http://www2.ca.uky.edu/HES/fcs/FACTSHTS/HF-LRA.151.PDF Responding to Color (PDF)] by the Cooperative Extension Service of the [[University of Kentucky]].  
* [https://accessibility.blog.gov.uk/2016/09/02/dos-and-donts-on-designing-for-accessibility/ Dos and Don'ts on designing for accessibility] and the accompanying poster on [https://accessibility.blog.gov.uk/wp-content/uploads/sites/52/2016/09/visually-impaired-low-vision.png designing for users with low vision (PNG)] by [[Karwai Pun]] at the [[UK Accessibility in Government Blog]]


[[Category:Vision Disabilities]]
[[Category:Vision Disabilities]]

Latest revision as of 19:34, 5 September 2021

For information about low vision, visit Low Vision on Perpendicular Angel.

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