Vitreous gel or vitreous humor is comprises a large portion of the eyeball. It is a clear gel-like substance that occupies the space behind the lens and in front of the retina at the back of the eye.

Because the eye must process visual data, this liquid must be clear enough for light to easily pass through it. Most of this humor consists of water, as well as a lower amount of collagen, salt, and sugar.

This humor is a stagnant (immobile) fluid that is not served by any blood vessels and is not actively regenerated or replenished.