Night Vision Test

What it measures

This experimental screen gives a rough, relative sense of how well you can pick out faint, low-luminance shapes on a near-black background once your eyes have had a moment to adapt to the dark. It loosely relates to the low-light, rod-driven vision you use at night — but it is shaped almost entirely by your screen and your room, not by clinical measurement.

How it works

After a short on-screen dark-adaptation period, you're shown a series of single digits drawn in progressively fainter grey on a near-black field. Each step the digit moves a little closer to the background luminance, so it becomes harder to make out. You identify each digit from four choices (or say you can't see it), and the tool records the faintest target you still read correctly. Because seeing dim targets depends on dark adaptation — the slow shift to rod-cell (scotopic) vision that takes many minutes in true darkness — the brief on-screen wait only gives a partial, approximate version of that process.

Tips for an accurate result

• 1Avoid bright light right before and during — Even a brief glance at a phone, a lamp, or a bright window resets dark adaptation and makes faint targets vanish. Keep your surroundings dim throughout the whole test.
• 2Sit at a steady, comfortable distance — Don't lean in to hunt for the digit. View the screen from your normal reading or working distance so the result reflects ordinary viewing rather than how close you can get.
• 3Re-test under the same conditions to compare — Because the result depends heavily on screen brightness and room darkness, only attempts done in the same conditions are comparable. Keep brightness and lighting consistent if you want to track change.