Tension Headache: This is the most common type of headache and can cause pain in the back of the head, as well as blurry vision due to muscle tension affecting the eyes. Tension headaches are often associated with stress and muscle strain.

Cervicogenic Headache: This type of headache is caused by referred pain from the cervical spine and can cause pain in the back of the head, as well as blurry vision due to the involvement of the cervical spine and surrounding muscles.
Migraine: While migraines are often associated with pain on one side of the head, some people may experience pain in the back of the head, and migraines can also cause blurry vision due to the neurological symptoms associated with the condition.
Occipital Neuralgia: This condition involves inflammation of the occipital nerve and can cause pain in the back of the head, as well as blurry vision due to the nerve's proximity to the eye.

Subarachnoid Hemorrhage: Although rare, this condition is life-threatening and can cause sudden, severe headache, including pain in the back of the head, as well as blurry vision due to increased intracranial pressure.
Giant Cell Arteritis: This condition can cause headache, including pain in the back of the head, as well as blurry vision due to inflammation of the blood vessels supplying the eyes.
Papilledema: Increased intracranial pressure can cause papilledema, which can lead to blurry vision, and may be associated with headache, including pain in the back of the head.

Chiari Malformation: A rare structural defect in the brain that can cause headache, including pain in the back of the head, as well as blurry vision due to the compression of the brain and spinal cord.
Idiopathic Intracranial Hypertension: A rare condition characterized by increased intracranial pressure without a known cause, which can cause headache, including pain in the back of the head, as well as blurry vision due to the increased pressure.