What makes up the vitreous?

• A. 99% water
• B. 1% collagen/hyaluronic acid
• C. 50% water and 50% collagen
• D. 75% water and 25% protein

Answer: (A)

The vitreous is a clear, gel-like substance whose bulk is water. About 98–99% of its makeup is water, with only a small fraction—roughly 1%—consisting of structural proteins and sugars. The gel’s framework comes mainly from collagen (especially type II) and the glycosaminoglycan hyaluronic acid, which together create a viscous, supportive network that gives the vitreous its consistency while keeping the eye optically clear. This dominance of water explains why the vitreous is so transparent and jelly-like, not a mostly solid mix. The other options overstate the solid content or misrepresent the proportion, whereas the key idea is that water is by far the major component.