The Diagnostic Engine

Before you begin

01Wear your usual glasses or contacts if you use them to read a screen.
02Sit about 18 inches from the screen in a softly lit room. Set your screen brightness to at least mid-level — a dim screen makes the patterns look fainter than they really are.
03Make sure no lamp, window, or overhead light is shining into your eyes or onto your screen — glare can skew your results.
04This test is meant for a generally healthy eye. If you have cataracts, glaucoma, macular degeneration, or very blurry vision that isn't corrected to roughly 20/50, your results may not be reliable.
05You'll test one eye at a time, covering the other.
06For each pattern, choose whether the bars run up, left, or right. The test takes about 3–5 minutes.
07Prefer the keyboard? Tap ← ↑ → to answer and u for unsure.

One account per person. We track your contrast per eye and measure progress over time, so having someone else test on your account will break your comparison and history data — each person should create their own account. Need to screen your household? Our lets up to 5 people share one account, each with their own private history.