Snellen Eye Vision Test — The Health Wiki
This app shows a series of letters (optotypes) scaled after screen calibration. It is not a replacement for a professional eye examination.
1) Screen Calibration
For accurate results, calibrate your screen using a real card (e.g., credit card: 85.6 mm wide). Drag the slider until the on-screen rectangle matches your real card width.
Drag the sides to match your card’s width on screen
Once matched, click “Save Calibration”
2) Test Conditions
Tip: Cover one eye (if testing one eye) and read the smallest line you can see clearly. Type the letters you see and press Check.