DimBright
FarNear
What is happening in the eye
Experiment 6 of 6: The blind spot
Test each eye, on this screen or with the printed card. Cover your left eye, look only at the plus, and find where the target vanishes (slide it, or move the card closer and farther). Then measure from your eye to the screen or card and enter it.
Distance (cm)Gap (cm)Angle
Right eye
Left eye
Gap: 12 cm on the printed card. On screen, measure it with a ruler.
Tips, and what you should see
- Click the slider once, then use the arrow keys so your eyes can stay on the plus.
- Keep looking at the plus. Even a quick glance at the target breaks the test.
- Lean slightly toward or away from the screen. The blind spot is about 15° from where you look, so sit about 4 times as far from the screen as the gap between the plus and the target (measure the gap with a ruler).
- Work on a laptop or desktop if you can. On a small phone screen the gap cannot get wide enough unless you hold the phone very close.
- Make sure the other eye is fully covered.
- With the line-with-a-gap target, the line looks continuous when the gap falls on the blind spot. Your visual system fills in the missing patch from the surroundings.