Photosensitivity

This is the page closest to my heart. For people with photosensitivity (like me) certain flashing or strobing visuals can trigger migraines, nausea, or seizures. The good news is that designing safely takes work upfont but provides lasting payoff. You're supporting more than just epileptics! There are many neurodivers individuals out there that benefit from accessible design practices as well.

An Important Rule: three flashes or fewer

The core standard is WCAG Success Criterion 2.3.1, “Three Flashes or Below Threshold.”

Reminder Nothing on the page should flash more than three times in any one second — and be especially careful with saturated red flashing, which is riskier than other colors.

A “flash” is a sudden change between light and dark (or strongly contrasting colors). Three flips in a second crosses into danger territory for many photosensitive people, so simply stay under it.

Things to screen before adding

Strobing GIFs, sparkles, or banners that flicker rapidly.
Fast flashing red, or rapid red/blue alternation — extra risky.
Auto-playing video with flashing scenes; let people press play instead.
Large, high-contrast moving stripes or checkerboards — fast repeating patterns can trigger symptoms too.
Sudden full-screen flashes on click, scroll, or page load.

Alternatives that still sparkle

Swap a strobing sparkle for a slow twinkle or a static glittery image.
Use gentle fades instead of hard on/off blinks.
Keep motion small and slow. A little bob reads well.
Honor prefers-reduced-motion so animations calm down automatically.
Consider a visible pause button for anything that moves on its own.

Check before you publish

Not sure about an animation or video? The free Photosensitive Epilepsy Analysis Tool (PEAT) from the Trace Center can test it for risky flashing, and the Epilepsy Foundation's photosensitivity resources are a kind place to learn more.

Polymeh's Experience

Why does Polymeh (Mae) wear blue glasses? Z-blue (the commercially available Z1 blue lens) filters the specific light wavelengths most likely to provoke a photoparoxysmal (seizure) response (a rare but often frequent type). In an Italian study of 610 photosensitive epilepsy patients, blue Z1 lenses made that EEG response disappear in about 76% of people and considerably reduced it in another 18% (Capovilla et al., Epilepsia, 2006).

Mr. Polymeh is also photosensitive and wears FL-41 glasses — a rose-amber tint that filters blue-green light around 480 nm — which help a bit with flashing lights and bright fluorescents.

My seizures are most often visually triggered, and strobes are my number-one trigger. For photosensitive epileptics striped patterns and even light patterns coming off trees/bushes can even be triggers. When designers choose gentle visuals, it is a thoughtful act. It makes my day every time! :)

Polymeh's Photosensitive Final Takeaway:. If there's only one photosensitive feature you add today, please consider a Pause/static page options. There's so many amazing sites I really wish to visit, and static options would help me (and other friends) visit more pages (while still keeping all the fun flashes intact for everyone else!).

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