Fourth Nerve Palsy is a condition where the eye's fourth cranial nerve, responsible for controlling a muscle that moves the eye up and down, is damaged or weakened. It is also known as Trochlear Nerve Palsy or Superior Oblique Palsy, as it affects the superior oblique muscle. Other synonyms for Fourth Nerve Palsy include Fourth Cranial Nerve Palsy, Fourth Nerve Paresis, and Cranial Nerve IV Palsy. The condition often causes double vision, and patients may experience difficulty with activities that require looking up or down. Treatment for Fourth Nerve Palsy may involve exercises to strengthen the affected muscle or surgery to address the underlying cause.