Glossary · Accessibility term
Low vision
Low vision is sight loss that ordinary glasses cannot correct, and it covers far more ground than a single blurred-vision picture suggests. Reduced sharpness, a restricted field, blind spots, lost contrast sensitivity and light sensitivity all sit inside it, along with colour vision deficiency and the changes that come with age. It is much more common than total blindness, roughly six people in seven of everybody with a visual impairment. Most of it comes from conditions like cataracts, glaucoma and diabetes, which makes this largely an older audience. What catches designers out is that there is no single set of settings to design for. Needs inside this group genuinely conflict. Somebody with light sensitivity can find the high contrast another person needs unreadable, and somebody with tunnel vision and sharp sight may make text smaller to fit more words in view. That is why the answer is user control rather than one optimised design, and why the rules that serve this group are all about what survives being changed.
In practice
Most people here are using an ordinary browser with the settings turned up rather than a screen reader, so what they meet first is your layout under pressure. Zoom, larger system text, a contrast theme and a screen magnifier are the tools, and the rules that matter are reflow, resize, text spacing and contrast rather than anything to do with ARIA.
Magnification solves one problem and creates another. Enlarging the page pushes most of it outside the field of view. Somebody at high zoom has something close to the experience of peripheral field loss, so a control sitting far from what they are reading may as well not be there. That is why a confirmation appearing in a corner, or an error at the top of a long form, gets missed by people who can see perfectly well where they are looking.
Text-only resizing is a separate need from zooming the whole interface, and a layout that copes with browser zoom can still break when only the text grows. Both are worth testing, and the failure to look for is not only overflow. Text disappearing entirely is the worse and commoner outcome, because a container with hidden overflow will simply eat it.
Why it matters
Low contrast text was found on 83.9% of the top million home pages in February 2026, up from 79.1% a year before. It is the single most detected accessibility problem there is, at 34 separate instances per page on average. That is this group's most common barrier and it is entirely a decision somebody made in a design tool. The reason it keeps happening is that testing gets done at 100% zoom on a large bright screen by people with good sight. That is the one condition under which pale grey on white looks fine. Zoom your own site.
What tends to break
Set a browser window to 320 pixels wide, or zoom to 400% in a normal window, and read one page of your own site. Watch for text that overflows its box, and for text that vanishes because the box hides it. Watch for a sticky header that grows until it covers half the screen, and for any line you have to scroll sideways to finish. None of that appears in a scan, and all of it is what this group meets every day.
Where this shows up on the site
Related terms
- ZoomZoom means enlarging a page, usually with Ctrl or Cmd and the plus key, and two WCAG rules govern what has to survive it.
- ReflowReflow is content rearranging itself to fit a narrow viewport instead of making you scroll sideways to read every line.
- Contrast ratioA contrast ratio is a number from 1:1 to 21:1 measuring how far apart two colors are in brightness, computed from a formula rather than judged by eye.
- Screen magnifierA screen magnifier enlarges part of the screen, from the zoom built into every operating system up to dedicated software like ZoomText.
- High contrast modeHigh contrast mode is an operating-system setting that throws away most of a site's colours and paints the page in a palette the user chose.
Knowing the word is the easy part.
Find out where your own site stands. The free scan checks 10 pages in a real browser against all 90 supported automated rules, separates 27 best-practice checks from its WCAG findings, and names the rule behind every result.