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New treatment can stop blinding disease

December 23, 2008 12:00:00 AM PST
It's an eye disease that forces people into a dark, blurry world. Every day, people with keratoconus watch their vision slip away. Until now, a cornea transplant was the only option. Now, a few tiny drops may save their sight. "I literally can see nothing unless it's six to eight inches away from my face," said Marsha Watts.

Where others see details, school teacher Marsha Watts sees only a blur. Every year, keratoconus takes away a little more of her sight.

"OS look like CS. CS look like GS. I can't see things at a distance. My night vision is very bad so I don't drive at night," said Watts.

A normal cornea is round, but in keratoconus the cornea stretches into a cone shape, blurring vision.

A clinical trial is testing a new treatment called CXL. Drops of riboflavin, or vitamin B2, are applied to the cornea in phases. An ultraviolet light activates the drops.

"There's a reaction between the ultraviolet light and the riboflavin, which joins or links the collagen molecules in the cornea and in doing so, makes it stiffer," said Dr. Doyle Stulting, Emory Eye Center.

That stiffness prevents the cornea from stretching, keeping its round shape. CXL is approved in Europe. Dr. Stulting was the first to perform the procedure in the U.S.

"It's not very often in your career where you have an opportunity to treat a disease that had no treatment available," said Dr. Stulting.

It can take months for vision to improve, but Marsha saw results quickly.

"I had tears in my eyes. I was so excited that at one week, already I was seeing improvement," said Watts.

She hopes that's a sign of things to come.

CXL is also being tested on a similar eye condition called ecstasia, which happens when people with weak corneas get Lasik surgery to correct their vision.

International trials show CXL slows the progression of both conditions, which cause 15-percent of cornea transplants.

Web Extra Information:

BACKGROUND:
Corneal collagen crosslinking with Riboflavin (CXL) is an experime ntal treatment for two eye conditions: keratoconus and ectasia. Currently, the conditions have no medical treatment and are responsible for 15 percent of corneal transplants in the United States. Keratoconus is a corneal disease that causes the cornea to weaken and gradually bulge outwards into a cone shape. Normal corneas are round and dome-shaped. The disease is estimated to affect every one of 2,000 individuals in the general population. In the early stages of the disease, blurring of vision and increased sensitivity to glare and light can occur. Symptoms typically first appear when individuals are in their late teens or early 20s. The condition can worsen for 10 to 20 years before stabilizing. Each eye may be impacted differently. Early vision changes from keratoconus, such as nearsightedness and astigmatism, can be corrected with glasses or contacts, but as the cornea continues to change, wearing contacts becomes difficult. In severe cases of keratoconus, corneal transplants may be necessary, where the keratoconus cornea is replaced with donor tissue.

Also referred to as iatrogenic keratoconus, ectasia is a condition that causes the cornea to bulge; however, in this condition the change in shape is caused by LASIK vision correction surgery. "These are people who had a propensity to develop keratoconus probably and simply developed it quicker or perhaps when they might not have developed it otherwise after they had LASIK," Doyle Stulting, M.D., Ph.D., an ophthalmologist at Emory University Eye Center in Atlanta, Ga., told Ivanhoe. LASIK penetrates the cornea more than other eye procedures and can cause excessive thinning and structural damage to the cornea. Ecstasia is usually diagnosed within the first two years following surgery.

HOPE IN A DROP:
CXL treatment works by increasing collagen crosslinking in the cornea. The crosslinks are responsible for maintaining the cornea's round shape. The procedure is done in the doctor's office and takes only a half hour. CXL first requires removing the corneal epithelium. Then, vitamin B, or riboflavin drops saturate the eye, which is then exposed to ultraviolet light. "During that time there is a reaction between the ultraviolet light and the riboflavin, which joins or links the collagen molecules in the cornea, and in doing so makes it stiffer than it otherwise would be," Dr. Stulting explained.

Although the procedure is still under investigation in the United States, preliminary results have shown CXL effectively stabilizes eyes. International clinical trials have also found CXL can stop the progression of keratoconus and ecstasia and improve vision. The effects appear to be long-term, as some European study participants were followed for up to eight years after they had the procedure. CXL is currently approved in Europe.

"As we move forward, I can envision a day where we will diagnose keratoconus very early, as soon as there are any abnormalities in the shape of the cornea," Dr. Stulting said. "We will crosslink those eyes and then they won't progress." Patients who are at risk for ectasia can be identified before having LASIK, so that they can undergo the CXL treatment and then safely have the eye correction procedure.


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