By: Deborah I. Friedman, MD, MPH
A red eye typically warrants immediate eye examination—at least the first time. Eye pain or headache with a normal external appearing eye nearly always has another answer than the eye itself when anyone seeks medical attention. The eyes deserve an exam to evaluate the nerves in the eyes and the optic discs when headache or eye pain is present. This is to eliminate increased pressure in the head and/or eye as a cause.
Many people will begin their quest for trying to find the cause for their headaches by seeking medical care with the ophthalmologist or optometrist. In fact, most eye pain does not result from an eye problem. Pain in and around the eye usually reflects referred pain from headache. “Referred” pain is pain that radiates from its originating location to another site. There are a few eye conditions that are important to consider.
What is eye strain?
“Eye strain” can produce eye discomfort and headaches, although it is uncommon and overrated as a cause of headache, especially headache associated with any function limiting activity. Eye strain is caused by improper focusing (nearsighted, farsighted or astigmatism), or when the two eyes are not properly aligned. Children under school age rarely complain of headaches from eyestrain. The typical headache of eyestrain starts after using the eyes, especially for extended periods of time, such as long periods of time using the computer, reading, or even sewing. Any number of tasks that require you to use your eyes for a long time may lead to a headache. For these individuals, it is important to make sure that, if needed, they have the appropriate prescription of eyeglasses. If the discomfort is caused by eyestrain, then it will be relieved with lenses or by correcting the alignment of the eyes.
Recognizing headache that is NOT due to eye strain
Most headaches are not due to eye strain. Some are tension-type headaches that have little to do with vision. Headaches that are present on awakening or those that wake one from sleep also are not caused by eyestrain. Additionally, eyestrain headaches are not generally associated with nausea or vomiting. For the vast majority of people with headaches, making changes to their glasses, using prisms, doing eye exercises and other types of “vision therapy” are generally not useful. Instead, these people have what is called a primary headache disorder, and these headaches are not related to visual concerns at all. The two most common primary headache disorders are migraine and tension-type headache.
Recognizing headache that may be due to eye strain or an eye problem
Cornea-related concerns: The clear surface in the front of the eye (cornea) has a rich nerve supply and is very sensitive. Even a small speck of dirt in the eye produces intense pain. Likewise, anything that disrupts the front surface of the cornea can be painful. When the cornea is scratched or injured, there is extreme pain and redness of the eye. Degenerative disease of the cornea can also be painful. Infections of the eye produce eye pain, redness, swelling and light sensitivity.
A less obvious cause of corneal pain is dry eyes. The cornea requires constant lubrication with a film of tears released from glands near the eye. If the tear film is not adequate and the front of the cornea is exposed directly to the air, it is painful. Other symptoms of dry eyes include redness, itching, burning, excessive tearing (it’s a reflex response), fluctuating blurred vision (“Every time I go to the eye doctor they change my glasses—I now have 5 pairs and my vision still isn’t clear”), the sensation of having something in the eye, a gravel sensation in the eye, seeing multiple images out of one eye, and frequent blinking. The symptoms are worsened by activities requiring visual concentration (reading, watching television, using the computer, driving).
Dry eyes can be caused by medications (for example, diuretics, antihistamines, antidepressants), medical disorders (such as systemic lupus, Sjögren’s syndrome, thyroid-related eye disease) or in a dry environment (an arid climate, constant use of heating systems in the winter). Sometimes, there is no underlying cause. The treatment is lubrication—frequent use of artificial tears during the day and a lubricating ointment at bedtime. Do not use saline. Products that “get the red out” will make the condition worse.
Eye Inflammation: Inflammation in or around the eye can be painful. It is generally accompanied by redness and swelling of the eye and eyelids, pain with eye movement and extreme sensitivity to light. The eye doctor will be able to see evidence of inflammation by looking into the eye using a microscope (slit lamp). Tumors inside the eye are often not painful, but a tumor behind the eye can cause pain. The pain is most often constant and the tumor will cause the eye to bulge forward. A tumor may also cause visual loss or problems with peripheral vision.
Glaucoma: The type of glaucoma that most people get (open angle glaucoma) is painless. However, an acute attack of angle closure glaucoma produces eye pain, blurred vision, and a bulging, firm, red eye. A mild attack may just cause pain in and around the eye. The attack may be provoked by going from darkness to light (for example, when leaving a movie theatre, or when the dilating drops given by the eye doctor wear off). Urgent attention is needed to bring the eye pressure down to normal. A simple laser procedure will prevent future attacks.
Optic nerve conditions: The eye doctor will also be able to look inside the eyes and see your optic nerves. The optic nerves are part of the brain, and they become swollen if there is high pressure in the brain. A brain tumor may cause the optic nerves to swell or produce double vision. Pseudotumor cerebri (also called idiopathic intracranial hypertension) is a disorder that produces high pressure in the brain with no tumor. It generally affects young, overweight women, producing headaches that are concentrated in or behind the eyes. There may be episodes of temporary visual loss (lasting seconds), blurred vision, double vision or a whooshing sound in the ears. Anyone being evaluated for headaches by any physician should be examined with an instrument called an ophthalmoscope for optic nerve swelling.
Giant cell arteritis (also called Temporal arteritis): This headache disorder typically occurs in persons over age 65 and can lead to permanent blindness if it is undetected. There is no specific cause, but the underlying problem is inflammation of blood vessels that can block blood flow. Sometimes the first symptom of temporal arteritis is visual loss. It is usually sudden, painless and dramatic. Most often it occurs in one eye, but can rapidly affect the other eye if untreated. The other symptoms of giant cell arteritis are headaches, tenderness of the scalp, pain or weakness of the jaw while chewing, fever, weight loss, loss of appetite, new onset of joint or muscle soreness, night sweats, depression and feeling poorly overall. The arteries in the temples and forehead will sometimes look prominent and be tender to touch. The diagnosis is made by hearing the patient’s complaints, obtaining blood tests known as C-reactive protein, and erythrocyte sedimentation rate and a biopsy of the artery under the skin of the temple. It is treated with corticosteroids to stop the inflammation. Once it occurs, the visual loss usually doesn’t improve, so early detection and treatment are important.
In conclusion, most patients with headaches don’t have any related eye problems and do not need to see an eye doctor for them. Most headaches are due to a primary headache disorder, and are generally classified as migraine or tension-type headache. However, it is important to know that there are a few exceptions that warrant a visit to your doctor’s office for further evaluation. These other eye conditions should be apparent to your doctor and you may need to go to an ophthalmologist for further evaluation. A careful recounting of your symptoms and a complete eye exam will reveal any of the conditions discussed above.
Deborah I. Friedman, MD, MPH, Professor of Neurology & Neurotherapeutics, Professor of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, TX.
This article is a legacy contribution from the American Headache Society Committee for Headache Education (ACHE) and the Fred Sheftell, MD Education Center.
Updated May 2008 from Headache, the Newsletter of ACHE, Spring 2000, Volume 11, Issue 1.