A complex system of nerves and muscles enables the human eye to blink, gaze, and shift focus. The trochlear nerve is one of six cranial nerves that carry electrical impulses from the brain to the eye.

Dear Doctors: I had an episode where it felt like my left eye went out of alignment and I couldn’t focus. A brain scan was clear, but the doctor said it’s cranial nerve palsy. He says it’s from a ...