Which structure is the tough, white outer coat of the eyeball?

Which structure is the tough, white outer coat of the eyeball?

• A. Aqueous humor
• B. Iris
• C. Sclera
• D. Cones

Answer: (C)

Think about the eye’s protective layers. The tough, white outer covering that gives the eyeball its shape and protection is the sclera. It forms the white part you can see around the eye and is continuous with the clear front surface (the cornea). The aqueous humor is just the clear fluid in front of the lens, not a coating. The iris is the colored ring that controls how much light enters, located in the middle layer. Cones are light-detecting cells in the retina at the back. So, the tough, white outer coat is the sclera.

Think about the eye’s protective layers. The tough, white outer covering that gives the eyeball its shape and protection is the sclera. It forms the white part you can see around the eye and is continuous with the clear front surface (the cornea). The aqueous humor is just the clear fluid in front of the lens, not a coating. The iris is the colored ring that controls how much light enters, located in the middle layer. Cones are light-detecting cells in the retina at the back. So, the tough, white outer coat is the sclera.