Eye

External layer :-

Sclera Protects and maintain shape of the eye ball.

Cornea :- Absorb O2 from the air, helps to focus light rays.

2. Middle layer :- 

Choroid :- Absorb light and prevent light from being  reflected within the eye ball.

Ciliary body :- Holds lens, regulate shape of the lens.

Iris :- Control amount of light entering

3. Inner layer:-

Ratina:- Vision in dim light, colour vision, vision in bright light.