Which term is the thick, transparent substance filling the center of the eye and giving it form and shape?

• A. Aqueous
• B. Accommodation
• C. Retinal pigment epithelium
• D. Vitreous

Answer: (D)

The thick, transparent gel that fills the main cavity behind the lens and gives the eye its form is the vitreous body (vitreous humor). It’s a gel-like substance that occupies the space between the lens and the retina and helps keep the retina pressed against the back of the eye, contributing to the eye’s shape.

Aqueous humor is the thin fluid in the front part of the eye (in the anterior and posterior chambers) and is constantly produced and drained. Accommodation is the process by which the lens changes shape to focus. The retinal pigment epithelium is a pigmented cell layer in the retina, not a filling substance. Therefore, the correct term for the thick, transparent center substance is the vitreous.