what is an eye made of?

Answer 1

The eyeball is made of layers of tissue, something like a balloon.

It is filled with vitreous fluid (firm like refrigerated jello) at birth.
As we age it gets more similar to jello out of the fridge for a while.

When pieces of the vitreous gel break loose from the inside of the eye it can cause floaters and flashing lights.

During a vitrectomy they actually put three holes in the eye ball to vacuum the vitreous gel out, while filling the eye with saline solution (if it were not filled it would collapse like a balloon). During this they repair whatever needs correction.

I hope this wasn't more than you wanted to know.