The parts labelled are:

I - IRIS

II - EYE LASHES

III - PUPIL

IV - SCLERA

The sclera, cornea, eyelids, eyelashes, and bony orbit all protect the eye from injury. 

Sclera - labelled IV

• The tough, white, fibrous tissue that surrounds the eyeball
• Helps maintain the eye's shape
• Protects the eye from injury
• Extends from the cornea to the optic nerve at the back of the eye

Cornea 

• The clear, curved layer in front of the iris and pupil
• Protects the front of the eye
• Helps focus light on the retina at the back of the eye

Eyelids 

• Thin flaps of skin and muscle that can cover the eye
• Reflexively close quickly (blink) to protect the eye from foreign objects, wind, dust, insects, and very bright light

Eyelashes - labelled II

• Short, tough hairs that grow from the edge of the eyelid
• Keep insects and foreign particles away from the eye