Promising therapy for 'eye stroke'

Fast action, clot busters can save vision in Johns Hopkins' experimental treatment

July 20, 2008|By Euna Lhee | Euna Lhee,Sun reporter

At first, Christine Jablonski didn't worry about the blurry vision in her right eye. She dismissed it as a flake of morning mascara and went about her daily business in Ellicott City. But within two hours, the eye went dark.

She rushed to Johns Hopkins Hospital, where doctors told her there was nothing they could do to restore her vision - she had suffered an "eye stroke" from a clot blocking a key blood vessel that supplies the retina.

But her daughter, a doctor, had heard about an experimental treatment pioneered by doctors at Hopkins' Wilmer Eye Institute. The hospital's Brain Attack Team, a group of physicians who specialize in strokes of the brain, was called in. They ran a catheter all the way from Jablonski's groin to her eyeball and injected a clot-busting agent.

"I could see my vision coming back. It was like a curtain of color," Jablonski said. Within two hours, her eyesight had returned to normal.

Her experience and reports of success with other volunteers in a seven-year Hopkins study raise hopes for up to 50,000 people who suffer eye strokes each year and would otherwise face irreversible loss of sight in one eye.

But Hopkins doctors caution that the experimental procedure carries its own serious risks, and success seems to depend on getting the patient into treatment as soon as possible. It didn't work at all on almost 25 percent of patients in the study, and other authorities say more trials are necessary before they can recommend the procedure.

Still, the Hopkins team was heartened by the results: Their volunteers were 13 times more likely than those undergoing conventional therapies to show significant improvement with standard eye charts. And they were almost five times as likely to achieve a final visual acuity of 20/100 or better on a 20/20 scale.

"We have a disorder that was basically irreversible, but with our technique, we see that a majority of patients experienced some level of improvement in their vision," said Dr. Eric Aldrich, a neurologist at the School of Medicine and lead author of a study published in the June issue of the journal Stroke. "No one has ever reported these types of results on such a large scale in North America."

An eye stoke, technically known as a central retinal artery occlusion, occurs when a clot forms in a small blood vessel within the eye. The interruption of blood flow destroys the retina, the light-sensitive nerve layer that captures images. The attack is sudden and painless, but it causes partial or complete vision loss in one eye. The other eye is usually unaffected.

Eye stroke is more likely to occur in the elderly, Hopkins researchers said. The condition appears to have the same heightened risk factors as brain stroke and heart disease. Those include diabetes, high blood pressure, elevated cholesterol levels, smoking and a family history of cardiovascular problems.

Under Aldrich's direction, a team of ophthalmologists, radiologists and neurologists developed a scheme to insert tissue plasminogen activator (TPA), a clot-dissolving agent, into an artery near the eye. They start by inserting a catheter into the patient's femoral artery in the thigh. Then, using an X-ray video display to show the way, they thread the tube up the bloodstream to the eye, where they administer TPA by drip until the blood clot dissolves.

From 1999 to 2006, 21 patients received TPA, while another 21 in their study received conventional therapies. Overall, 76 percent of the TPA group improved their vision by at least one line on the Snellen chart - the eye chart with the big "E" at the top. Only 33 percent in the standard therapies group showed that much improvement.

In addition, a third of volunteers in the TPA group experienced an improvement of three lines or better, compared with 5 percent of patients in the standard group.

"This was a condition that has never had any useful treatment. We have done things to help the eye reduce the pressure, but none really work to any degree," said Dr. Neil Miller, the team's lead ophthalmologist. "Most patients end up blind or nearly so."

Current FDA-approved therapies include paracentesis (sticking a needle into the eye and withdrawing fluid), breathing a mixture of carbon dioxide and oxygen gas, and eye massage. All are designed to restore blood flow, but none works well.

TPA is typically used to treat stroke and heart attacks, but in 1996, German researchers tried it on eye stroke victims for the first time. Hopkins researchers modified the technique to reduce the length of the procedure, the quantity of drug used and the danger of complications, which can include bleeding, damage to arteries and stroke.

All of the team's patients were treated within 15 hours of losing vision. The time element is critical, Aldrich says, because the eye tissue dies gradually over the next few hours.

"Time is retina. If you restore blood to the tissue sooner, then you have a greater chance of recovery," Aldrich said.

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