Medical Monday – Photosensitive Epilepsy – Is Your Site Seizure-Free Friendly?

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There are many types of seizure disorders but there is one that I feel is important to touch base on as a blogger – Photosensitive Epilepsy.  Why do I feel this way?  The reason is because often times we tend to manage our site including background images, site headers, banners, and buttons.  For some bloggers they may be able to design their site from scratch.  Our choices can ultimately effect who will be able to visit our sites or become long term readers.  Personally, I don’t want to exclude any individual with a disability in being able to visit my site.  If there is information out there to help me make my site a compatible site for those with disabilities – I will educate myself on how to make this happen.

What is photosensitive epilepsy?  In a nutshell, these are seizures brought on by flashing lights, rapidly changing or alternating images, as well as static spatial patterns such as squares or stripes. Mouse-overs that cause large areas of a PC screen to flash rapidly on and off are contributors to bringing on this type of seizure in addition to going from dark to light.  Many other factors contribute to this type of seizure disorder; however I won’t get into the nitty gritty of them, but you can read a good article {here}, if you’re interested in learning more.  Children have had issues in years past with this type of seizure disorder from television broadcastings causing mass seizures in children.  A good article to read mainly pertaining to these types of seizures in children can be found on the Canadian Epilepsy Alliance site.  Please note – these seizures don’t just pertain to children – adults have this type of seizure too.

Let’s take this a step further.  The World Wide Web Consortium (W3C) – is the international standards organization for the WWW (W3 or World Wide Web).  Their job is to address and develop Web Content Accessibility Guidelines.  In 2008, Version 2.0 specifies content should not flash more than 3 times in any 1-second period.  Flashing above this rate is allowed if the flashing is below the “general and red flashing thresholds”.  That basically means it is okay to flash more than 3 times in a 1 second period if the flashing is low enough in contrast and small enough.  A free tool is available to web developers to determine if a site meets W3C guidelines.  The tool is Photosensitive Epilepsy Analysis Tool (PEAT).

United States federal agencies are governed by section 508 of the Rehabilitation Act.  This particular act states that pages shall be designed to avoid causing the screen to flicker with a frequency greater than 2 Hz and less than 55 Hz.  When the 508 regulations are updated it is expected that they will use the same criteria as WCAG 2.0.

How can you as a site owner make your site seizure-free friendly?

• Don’t put rapidly flashing banners on your site.
• Don’t put rapid flashing banners that go from light to dark or vice-versa.
• Don’t have your background look like one of those illusion posters – they are too visually busy for those with this type of seizure disorder.
• Don’t have rapidly moving scrolling or rotating widgets on your site.
• Don’t have large areas of darkness lead into large areas of lightness and vice-versa.  FYI – Many individuals have these seizures simply from getting out of a vehicle into daylight or going from inside a home to the daylight outside and vice-versa.
• Take a break from looking at your site – when you come back does anything stick out to you that is hard on the eyes at a first glance?  Even certain types of fonts have been noted to effect people with these types of seizures.

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