Free tool
Visual Disability Simulator
See how people with different visual disabilities perceive your web content.
Understanding visual disabilities
Protanopia
Protanopia is a form of color blindness where red-sensitive cones are absent. Affected people confuse red and green, and perceive red as dark brown or black.
Deuteranopia
Deuteranopia is the most common form of color blindness. Green-sensitive cones are absent, causing confusion between red and green. It is genetic and mainly affects men.
Tritanopia
Tritanopia is a rare form of color blindness where blue-sensitive cones are absent. Affected people confuse blue and yellow, perceiving them as shades of pink and green.
Achromatopsia
Achromatopsia is a rare condition where no cones function. The person perceives only shades of gray, often with increased light sensitivity (photophobia) and reduced visual acuity.
Cataract
Cataract is a progressive clouding of the eye lens, causing blurred vision, yellowing of colors and increased glare sensitivity. Very common in elderly people.
Tunnel Vision
Tunnel vision (or visual field constriction) can be caused by glaucoma, retinitis pigmentosa or stroke. The person can only see a small central area, making screen navigation very difficult.
Dyslexia
Dyslexia is a specific learning disorder for reading. Dyslexic people may see letters moving, mixing or reversing. Accessible design (spacing, fonts, contrast) significantly reduces difficulties.
FAQ
Color blindness is a color vision disorder that affects about 8% of men and 0.5% of women. There are different forms: protanopia (no red), deuteranopia (no green) and tritanopia (no blue). Color blind people do not see in black and white, they confuse certain colors.
Simulating visual disabilities helps concretely understand how your content is perceived by some of your users. It helps make better design decisions, like not conveying information through color alone (RGAA criterion 3.1).
Three main rules: 1) Never use color alone to convey information (add icons, patterns or text). 2) Ensure sufficient contrast (4.5:1 minimum). 3) Use color palettes that are distinguishable even with altered vision.
RGAA requires that information is not conveyed by color alone (criterion 3.1), that contrasts are sufficient (criteria 3.2 and 3.3), and that content is accessible to screen readers (criteria 1.x for images, 8.x for structure).
The simulations are approximations based on recognized scientific models. They give a good idea of altered perception, but each person with a visual disability has a unique experience. Simulations remain an excellent tool for awareness and testing.