Contrast Sensitivity Test
Read letters that fade step by step to get a rough score for how well you see low-contrast detail.
A standard eye chart shows black letters on a white background, which is maximum contrast. Real life is rarely like that: a grey kerb at dusk, a pale face in fog or a step of the same colour as the floor all have low contrast. Contrast sensitivity describes how well you can tell an object from its background when the difference in brightness is small. It is possible to read the chart perfectly and still struggle with low-contrast scenes.
In this test, letters of the same, easily readable size are shown with gradually decreasing contrast, getting paler and paler against the background. You report the faintest letters you can still read correctly, and the tool converts this into a rough contrast sensitivity score. Reduced contrast sensitivity is linked to cataract, glaucoma, macular disease, dry eye and normal ageing, and it often explains complaints about night driving or dim rooms.
Because screens differ in brightness, gamma and how finely they render faint greys, this is an approximate, informal measurement and not comparable to clinical charts such as the Pelli-Robson chart. It is most useful for comparing your own results over time on the same device and in the same lighting.
How to use
- Use the same device each time, with brightness at a comfortable medium-high level and night mode switched off.
- Sit about 1 metre from the screen in a normally lit room, without reflections on the screen.
- Wear your usual distance or computer glasses.
- Test both eyes together first, then each eye separately with the other covered, if the tool offers it.
- Read the letters from the darkest to the faintest and enter what you see; guess when unsure.
- Stop at the step where you can no longer read letters correctly and note your score.
Reading your result
A higher score means you can read fainter letters, which indicates better contrast sensitivity. Young adults with healthy eyes usually read well into the faint rows; scores tend to fall gradually with age.
A clearly lower score than expected for your age, a noticeable difference between the two eyes, or a decline compared with your earlier results is worth discussing with an eye-care professional, especially if you also notice glare from headlights, hazy vision, or difficulty in dim light. Cataract is a common and treatable cause. Dry or tired eyes, smudged glasses and screen settings can temporarily lower your score, so repeat the test if you are unsure.
Caution: Screening only, not a diagnosis. Screens cannot reproduce clinical contrast levels exactly. Any sudden drop in vision or contrast needs prompt medical assessment.
Frequently asked questions
How is contrast sensitivity different from visual acuity?
Acuity measures the smallest detail you can see at high contrast; contrast sensitivity measures how faint a pattern can be before you lose it. Both matter for everyday vision.
Can glasses improve contrast sensitivity?
Correcting a refractive error helps a little, and clean lenses with an anti-reflective coating reduce glare. Large losses usually have a medical cause that needs treatment.
Why is my score lower in the evening?
Tiredness, dry eyes and lower room lighting can all reduce contrast performance temporarily. Test at a similar time and in similar lighting for a fair comparison.