Corneal reflex is a test done in which our cornea is gently touch by a cotton whisk to see the blinking response. When the reflex is intact the eye should blink.
This test, tests the 5th cranial nerve’s ophthalmic component.
The sensory (afferent) stimuli (in this case the touch of cotton whisk)from the surface of cornea is carried by 5th cranial nerve’s ophthalmic component.
The efferent or motor supply returns via 7th cranial nerve (that is the facial nerve) which causes blinking of eye by its action on the eyelid.