A third cranial nerve paralysis is usually treated an an emergency. Paralysis of this nerve can give variable symptoms. Sometimes people will notice double vision on in some extreme position of gaze. This nerve is particularly prone to damage from head trauma, sometimes even just a bad bump on the head. Vascular problems such as diabetes can rarely cause this as well.
Prisms placed in glasses can usually reduce double vision until the nerve function returns.
The sixth cranial nerve controls the muscle that turns the eye outward. Thus, is paralyzed, the eye will turn inward, and often cannot often cross the midline back toward the outside. This is commonly caused by vascular problems such as diabetes, and the nerve function returns in 1 to 3 months. Other problems such as tumor, temporal arteritis, and stroke can cause this as well. It is felt to be an auto-immune problem where the immune system attacks the tissues around the eye, and possibly also the thyroid gland.