Phosphenes

Closed-eye hallucinations and closed-eye visualizations (CEV) are hallucinations that occur when one's eyes are closed or when one is in a darkened room. They are not the same as phosphenes; perceived light and shapes when pressure is applied to the eye's retina, or some other non-visual external cause stimulates the eye. Some people report CEV under the influence of psychedelics; these are reportedly of a different nature than the "open-eye" hallucinations of the same compounds. Similar hallucinations that occur due to loss of vision are called "visual release hallucinations".