Entoptic phenomena

Under suitable conditions light falling on the eye may render visible certain objects within the eye itself. These perceptions are called entoptical.

Entoptic images differ from optical illusions because, whereas illusion is a phenomenon happening in the brain, entoptic phenomena take place within the observer's own eye. In this sense, the observer cannot share this experience with others, because in fact the image is caged within his eyes.

What does it mean to own an image?
And a non-image?

Are entoptical images existing? Can we consider them 'real'?
What is a real image then? Are entoptical images onlogically different from images whose perception we can share? And from those having a physical material reference?

Some make research struggling to quest for answers. Others are raising further questions...