From which sources does the cornea receive oxygen and nutrients?

From which sources does the cornea receive oxygen and nutrients?

• A. Only from retinal vessels
• B. The fluid in front of and behind the cornea and from the conjunctival blood vessels
• C. Only from the aqueous humor
• D. Only from the scleral blood supply

Answer: (B)

The cornea gets its oxygen and nutrients through diffusion from surrounding fluids because it has no blood vessels of its own. Oxygen and nutrients come from two key internal sources: the tear film on the front surface provides oxygen (from the atmosphere) and nutrients to the outermost layers, while the aqueous humor behind the cornea supplies nutrients to the deeper layers. In addition, the peripheral cornea near the limbus receives nourishment from the conjunctival blood vessels that extend toward the cornea. That’s why retinal or scleral blood supplies don’t directly feed the cornea, and why relying on only one source (like aqueous humor alone) isn’t complete—the tear film also plays a crucial role for the outer layers.

The cornea gets its oxygen and nutrients through diffusion from surrounding fluids because it has no blood vessels of its own. Oxygen and nutrients come from two key internal sources: the tear film on the front surface provides oxygen (from the atmosphere) and nutrients to the outermost layers, while the aqueous humor behind the cornea supplies nutrients to the deeper layers. In addition, the peripheral cornea near the limbus receives nourishment from the conjunctival blood vessels that extend toward the cornea.

That’s why retinal or scleral blood supplies don’t directly feed the cornea, and why relying on only one source (like aqueous humor alone) isn’t complete—the tear film also plays a crucial role for the outer layers.