Pain in the Eye

This article is from October 2008 and may contain outdated material.

Meet the patients whose pain evades easy solutions.

A 23-year-old woman sustains an alkali burn to her right eye. The acute injury is treated, but she nevertheless requires a corneal transplant. Although the transplant is stable and her eye shows no inflammation, she develops severe, unrelenting pain in that eye. The pain is boring in nature and associated with severe photophobia and frequent migraine headaches. The pain fails to respond to local anesthetic drops or oral steroid burst and taper. She is placed on short-acting narcotics, but the pain continues to worsen. Other examinations, including neurological assessment, MR scan and ultrasound of the orbit, are completely normal.

Patients, like this young woman, who present with ocular pain that persists despite normal findings on examination, or who report chronic eye pain, defined as three to six months or longer, are some of the most challenging cases that can confront an ophthalmologist, particularly if the pain is neurogenic, idiopathic, intractable or refractory.

Fortunately, this young woman came under the care of a neuro-ophthalmologist, who diagnosed neurogenic eye pain, migraine without aura, rebound headaches from short-acting narcotics, and mild depression. The narcotics were discontinued, and the patient was placed instead on gabapentin, low-dose methadone and an anti-depressant. Acute migraines were managed with a triptan. Although the patient is still in pain, she finds it tolerable and has been able to resume activities.

Take a Good Hx, Make an Accurate Dx

Ophthalmologists who are experienced in the management of the complexities of eye pain strongly agree on two things: the importance of a thorough history and of an accurate diagnosis in patients with serious pain. “One of the best ways to figure out the etiology of pain is to take a good history,” said Peter A. Quiros, MD, assistant professor of ophthalmology at the University of Southern California in Los Angeles. “Ask about the quality of the pain, its duration, its frequency and if there is anything reproducible bringing on the pain. Those four factors often can help determine the nature of the pain.”

The importance of pain as a presenting symptom was underscored by Susan M. Tucker, MD, director of oculoplastic surgery at the Lahey Clinic Eye Institute and assistant professor of ophthalmology at Tufts University. “Pain is an important symptom not to ignore,” Dr. Tucker said. “Physicians should establish what the cause is and proceed to management of that cause.”

For ophthalmologists, their limitations lie not in addressing acute pain but in chronic, long- term pain management, according to C. Robert Bernardino, MD, associate professor of ophthalmology and director of residency programs at Yale University. “When we see chronic orbital pain, for example, we try to figure out if it is an anterior, posterior, intraocular or orbital problem. Oftentimes, we turn toward collaboration with neurologists, pain specialists, anesthesiologists or psychiatrists.”

Diagnostic pitfalls. Gregory S. Kosmorsky, DO, head of neuro-ophthalmology at Cleveland Clinic emphasizes some of the frustrating issues of making a diagnosis. “Pain is subjective and highly variable. It cannot be quantified, which makes it an enigma, and it is colored by emotion and by previous experience. Pain is difficult for us as physicians to deal with.” Dr. Kosmorsky recommends a good eye examination to assure that a patient with intraocular eye disease is not referred inappropriately to a neurologist or neuro-ophthalmologist. “Make sure it is not iritis, uveitis or inflammatory pseudotumor. Make sure it is not a foreign body in the eye. You must exclude these conditions as an ophthalmologist.”

It’s also important not to miss a secondary cause of headache with eye pain that may not have obvious findings on eye examination, such as intermittent angle closure or early herpes zoster, presenting as knifelike eye pain before any lesions appear, said Kathleen B. Digre, MD, professor of ophthalmology and neurology at the University of Utah in Salt Lake City. “Imaging may be required to rule out secondary causes of eye pain.”

Consideration also must be given to systemic disease, Dr. Digre added. Headaches involving eye pain may indicate underlying diseases that need to be included in the differential diagnosis, she said. “Age can provide a diagnostic clue. If a patient is more than 65 years old, there is more likelihood of giant cell arteritis, carotid artery disease or atherosclerosis.”

The Causes and Effects of Eye Pain

“I would first approach eye pain anatomically,” said Dr. Digre. “The eye has rich trigeminal innervation and the trigeminal system is huge, with the first division radiating to the eye. Because this first division also innervates the dura, a dural problem may present as eye pain.”

Pain from deep in the brain. The trigeminal nerve, or fifth cranial nerve, arises from the pons and divides into three main branches, which then subdivide into a complex network of nerves. The ophthalmic nerve supplies most of the scalp, the upper eyelid, tear gland and cornea. “Eye pain by itself is a major differential diagnosis,” Dr. Digre said. “It is because this anatomic structure of the trigeminal system is geared mainly toward the innervation of the eye and orbit.”

For ophthalmologists, the trigeminal nerve is the pain mediator of concern, Dr. Quiros agreed. “Many of our therapies focus on it.” When acute pain first starts, the trigeminal nerve is sending signals to the pain centers of the brain and they are responding, but when pain becomes chronic, the central pain receptors become upregulated and become sensitized to the pain, he said. “The patient may feel the sensation of pain, but there is actually no pain there, which makes it very difficult to treat,” he said.

The pain-sensitive cornea has one of the densest sensory plexuses in the body, Dr. Kosmorsky noted. “The cornea is unique in that the trigeminal nerve is only five cell thicknesses from the surface of the body. Nowhere else in the body are bare nerve endings closer to the surface than in the cornea. A tiny foreign body can feel like the Prussian army marching on your eye.”

Four major culprits. Patients who present with intermittent pain around the eyes may think their eyes are causing the problem. But if the eyes are normal on examination, this may mean the ophthalmologist is dealing with a headache disorder that affects the eyes. At least four distinct causes are possible.

1. Migraine. Migraine is the most common headache disorder that causes ocular pain, Dr. Digre said. It is characterized by throbbing pain, photophobia and sometimes by nausea or visual disturbances. She estimates that as many as 20 percent of women and about 10 percent of men who present to an ophthalmologist with pain have migraine. She advises ophthalmologists to ask three quick, easy questions to make the diagnosis. If two of the three questions elicit a positive answer, then the diagnosis is likely to be migraine.^1,

• Are you light sensitive?
• Is the headache disabling?
• Is there nausea or vomiting?

“Generally, migraine patients should be referred to a neurologist or neuro-ophthalmologist who regularly deals with headache disorders,” Dr. Digre said. “There are some ophthalmologists who are comfortable treating migraine, but most who are not comfortable simply have not been trained to do this.”

2. Cluster headache. Only one type of headache affecting the eye is more common in men than in women, according to Dr. Digre. Cluster headache usually presents in young and middle-aged men with episodic eye pain, lasting from 15 minutes to two hours. It is usually characterized by some sympathetic dysfunction, such as Horner’s syndrome as well as lacrimation or rhinorrhea.

When a male patient presents with bouts of one-hour eye pain, with tearing and a droopy eyelid, that’s very likely to be a cluster headache, said Dr. Digre. She pointed out that when a woman comes in with the same symptoms, the diagnosis could be cluster headache or paroxysmal hemicrania, which is more common in women.

3. Hemicrania. Headaches identified as hemicrania may be episodic, as in paroxysmal hemicrania, or nearly unremitting, as in hemicrania continua. Dr. Quiros said that the latter is underdiagnosed and often mimics trigeminal neuralgia (discussed below).

The common diagnostic characteristics of hemicranial headaches include pain occurring on one side of the head with distribution to the first branch of the trigeminal nerve. Fortunately, both paroxysmal and continua headaches respond well to the same treatment.

“Hemicrania always responds to indomethacin,” said Dr. Quiros. “It has a 100 percent response rate. When ophthalmologists try indomethacin and the pain goes away, the diagnosis has been made.”

4. Trigeminal neuralgia. Trigeminal neuralgia, or tic doloureux, is probably the most severe, chronic ocular pain condition, and it causes extreme, sporadic, burning or shocklike pain, according to Dr. Quiros. “The pain is repetitious through the day. It can occur daily for several minutes a day or it can occur 10 times per day. It can be constant in duration. It can last for many days, months or continue on forever. The pain can be triggered by vibration or contact, such as combing hair, brushing teeth, touching the temple or a blast of cold air,” he said.

The idiopathic pain of trigeminal neuralgia usually occurs in patients over 50 years of age, generally in women rather than in men, Dr. Quiros said. This is commonly seen when patients develop herpes zoster, an infection that may cause agonizing pain that is resistant to medical therapy, he added. Antiviral agents may arrest the infection, but not prevent postherpetic neuralgia.

Management? Make It Stop!

Narcotic analgesics. For patients with acute pain, opioid agents have been widely—if carefully—accepted in the ophthalmic community. “When you’re using narcotic analgesics for short-term, significant pain, you don’t have to be worried,” said Dr. Tucker. “I have no problem keeping patients on strong narcotics short-term, and then they are quickly tapered afterward. It’s when the pain continues on for months and seems to become a chronic problem, that’s when I refer to a pain specialist or neurologist or other appropriate specialist.”

Treating trigeminal neuralgia. The management for trigeminal neuralgia starts with anticonvulsant medications, such as gabapentin or carbamazepine, which can be useful for prolonged periods of time without any complications, according to Dr. Quiros. “The vast majority of patients respond to these medications. If these agents do not get rid of the pain completely, they usually dull the pain significantly. In severe cases, with no response to these medications, narcotic analgesics may be tried, but only in the short-term because long-term use often makes matters worse.”

For patients with first-division trigeminal neuralgia, Dr. Tucker is using a procedure that may provide longer duration of pain relief than conventional supraorbital neurectomy. In a series of patients with shooting or lancinating pain, she has performed anterior orbitotomy with resection of the frontal nerve and its branches, the supratrochlear and supraorbital nerves. “What I do for this small segment of patients is to resect or remove as large a segment as I can of the frontal nerve, which eliminates the pain in this distribution of the trigeminal nerve, although it also leads to numbness,” Dr. Tucker said. She has followed 11 patients for six months to six years, with a mean follow-up of four years and regards the technique as “promising.” She said the majority of patients have done very well, with only two patients experiencing recurrences.

Dr. Tucker noted this procedure would not be appropriate for patients who have pain in the second or third division of the trigeminal nerve; they should be referred to a neurosurgeon. Dr. Digre added that the most accepted procedure for trigeminal neuralgia is microvascular decompression.

Other therapies include percutaneous balloon decompression, percutaneous glycerol rhizotomy, percutaneous stereotactic radio frequency thermal rhizotomy and stereotactic radiosurgery.²

Neurology’s guidelines. The American Academy of Neurology (AAN), in partnership with the European Federation of Neurological Societies, has issued guidelines on treating trigeminal neuralgia with surgery in patients who have not responded to pharmacologic agents (primarily carbamazepine and oxcarbazepine). “If people fail to respond to these drugs, physicians should not be reluctant to consider referring the patient for surgery. Often surgery is considered a last resort and patients suffer while the well-intentioned physician tries other medications with limited effectiveness,” according to guidelines author Gary S. Gronseth, MD, professor of neurology at the University of Kansas in Kansas City. The guidelines were published online Aug. 20 in Neurology, but physician summaries can be seen by non-AAN members by going to www.aan.com/practice/guideline/uploads/303.pdf.

Working with other clinicians. Collaboration with a primary care physician is warranted when patients with eye pain have comorbid conditions. “Patients with inflammatory syndromes who also have diabetes or hypertension require working in concert with the internist for their care,” said Dr. Quiros. “Steroid therapy may worsen the hypertension and will always worsen the diabetes, so that diabetic therapy has to be adjusted while they are on steroid therapy.”

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1 Lipton, R. et al. Neurology 2003;61(3):375–382.

2 www.mayoclinic.org/trigeminal-neuralgia/treatment.html#surgery.

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EyeNet would like to offer special thanks to Dr. Digre for her assistance on this article.