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.
This free online contrast sensitivity test is a quick, educational way to see how well your eyes detect subtle differences between light and dark — the kind of vision used for night driving, reading in dim light, and noticing low-contrast objects. While it cannot diagnose any eye condition, it may flag patterns worth discussing during a comprehensive eye exam. You may also find our pages on dry eye treatment, digital eye strain, and night vision difficulty helpful for understanding how contrast affects daily visual performance. If you live in Ontario, Canada, you can also book an online eye health consultation with Dr. Roxanna Gangi.
Disclaimer: This online contrast sensitivity test is for educational and informational purposes only. It does not diagnose eye disease, measure your prescription, or replace a comprehensive eye examination. Screen brightness, device quality, lighting, and display settings can affect results. If you experience sudden vision loss, severe eye pain, flashes of light, trauma, or other urgent symptoms, seek immediate medical attention, or book a comprehensive eye exam or professional consultation with Dr. Roxanna Gangi.
How to take this test
- Set your screen brightness to maximum and reduce glare.
- Sit about 50–60 cm (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 can't see it, tap Can't see it.
Take the test
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 an expert opinion from anywhere in Ontario?
Online tools are a great starting point, but a one-on-one review with Dr. Roxanna Gangi, Optometrist can put your results in context and guide your next steps. Anyone living in Ontario, Canada can book a secure online consultancy — no need to travel to the clinic.