There are a number of eye disorders that cause headache, but the most common cause of eyestrain headache is due to uncorrected refractive errors. For example, if someone is long-sighted and has to read a book without their glasses, the prolonged eyestrain can cause headache. Other causes of headache are inflammation of the eye or optical nerve. There are a number of inflammatory conditions that cause headache, such as iritis, conjunctivitis, and others. Pain is generally exacerbated by applying pressure to the eye. On the other hand, if the nerve is inflamed (trochlear inflammation), the pain will increase from looking around and moving the eye.
