What is the transparent, colorless mass that fills the eyeball behind the lens?

The vitreous humor is the transparent, colorless gel-like substance that occupies the space behind the lens and in front of the retina in the eye. This substance plays a critical role in maintaining the shape of the eyeball and ensuring light is properly transmitted to the retina for vision. Its jelly-like consistency also helps to support the retina, keeping it in place against the inner wall of the eye.

In contrast, the aqueous humor is a different fluid that fills the anterior chamber of the eye, located between the cornea and the lens. It is responsible for providing nutrients to the avascular structures of the eye, such as the lens and cornea, and plays a key role in maintaining intraocular pressure.

The third option, corneal humor, is not an anatomical term used in ocular anatomy; the cornea itself does not contain a specific humor but rather is comprised of layers of transparent tissues that allow light to enter the eye.

Scleral humor is also not a recognized term in the context of ocular anatomy. The sclera is the outer protective layer of the eye, commonly referred to as the "whites of the eyes."

Understanding these distinctions helps clarify why the vitreous humor is the correct answer regarding the substance filling the area behind the lens