Screening tool · 2 min
Online Contrast Sensitivity Test
Check how well you can distinguish low-contrast letters on your screen.
What this test measures
Your ability to detect subtle differences between light and dark — the part of vision used for night driving, reading in dim light, seeing in fog or rain, and noticing low-contrast objects.
Why it matters
Contrast sensitivity can decline before standard 20/20 letter charts show any change. Reduced contrast vision is associated with cataracts, glaucoma, dry eye, diabetic eye disease, and natural age-related changes.
Who may benefit
Anyone who finds night driving harder than it used to be, struggles in low light, experiences glare from oncoming headlights, or wants a quick screen-based awareness check before booking a comprehensive eye exam.
Disclaimer: This tool is for educational purposes only and does not replace a professional eye examination. Screen brightness, calibration, lighting and viewing distance all influence results. For an accurate assessment, request a comprehensive exam with Dr. Roxanna Gangi, your trusted Optometrist in Toronto and York Region.
How to take this test
- Set your screen brightness to maximum and reduce glare.
- Sit about 50–60 cm (about arm's length) from your screen.
- Wear your usual glasses or contact lenses if you have them.
- For each step, tap the letter you see. If you cannot see it, tap Can't see it.
Take the test
Choose a difficulty
Letters get fainter at each step. Easy is a gentle screening; Hard is the most challenging.
Default is Medium. Tip: turn screen brightness up before starting.
What can affect contrast sensitivity?
Cataracts
Clouding of the eye's natural lens scatters light and reduces the ability to see low-contrast detail, often before standard letter charts change.
Glaucoma
Damage to the optic nerve can quietly reduce contrast and peripheral awareness long before central vision is affected.
Diabetic retinopathy
Diabetes-related changes in the retina can lower contrast sensitivity and cause fluctuating vision.
Dry eye
An unstable tear film blurs the optical surface of the eye, making low-contrast letters and edges harder to see.
Aging
Contrast sensitivity naturally declines with age, even when standard 20/20 acuity is preserved.
Uncorrected prescription
Out-of-date glasses or unrecognized astigmatism reduce sharpness and contrast at distance and near.
Digital eye strain
Long screen sessions reduce blink rate and dry the eye surface, temporarily reducing contrast and clarity.
Poor lighting
Dim or uneven lighting forces the eye to work harder and reduces perceived contrast.
Screen brightness
Low screen brightness, glare, or a low-quality display can mimic reduced contrast sensitivity.
Patients in Toronto, Aurora, Newmarket, Richmond Hill, Thornhill, Vaughan, and York Region can book a comprehensive eye exam with Dr. Roxanna Gangi through Pro Eye Exam.
Frequently asked questions
Want a real, in-person assessment?
Online tools are a great starting point, but a comprehensive eye exam with Dr. Roxanna Gangi can detect conditions that screen-based tests cannot — including glaucoma, diabetic retinopathy, and early macular changes.