Pain in the back of the head with eye pain consider elevated eye pressure, visual fatigue or inadequate blood supply to the brain as the cause.
High intraocular pressure, such as glaucoma, can result in a headache with orbital pain and possibly blurred vision.
Visual fatigue is most often due to lack of sleep and overuse of the eyes and may present as a headache with eye pain and a feeling of weakness.
Inadequate blood supply to the brain such as cervical spondylosis and atherosclerosis of the brain arteries.