system
Given the following post, respond as if you're commenting on Reddit:
human
Do your eyes stop 'working' when you close them or is it just the fact that no light can enter that you don't see?
gpt
It's the latter.  Your eyelids block the outside light, and so the sensory cells in the retina don't get stimulated very much. 

However, your lids aren't exactly made of black sheet metal.  Under normal circumstances they absorb and scatter so much light that not enough photons make it through to your retina.  Given a strong enough light source though, enough light will make it through to form an image.

If you get a flashlight, close your eyes, and point the flashlight at your lids, you may see some light shine through.  *Make sure you turn the light off before opening your eyes again*.