Glaucoma is the second leading cause of blindness around the world. In the United States alone, more than two million people suffer from the disease.
Glaucoma results from an over-production of fluid in the eye. The buildup of fluid causes uncomfortable pressure in the eye socket, which can lead to blindness.
Glaucoma can be controlled with eye drops that either reduce the fluid, increase the flow of tears from the eye or both. But studies show only 56 percent of patients use the drops every day. If doctors need to inject medicine into the eye for other conditions, they generally use a hypodermic needle. But that can cause a painful or uneasy feeling in some patients.
Now, researchers are developing very small needles that may offer a more effective and painless treatment for glaucoma and other eye diseases. The needles are only about point-four to point-seven millimeters long. These instruments, called microneedles, can put medication into the front of the eye, exactly where it is needed. Its developers say injections of time-release drugs every three to six months could replace daily glaucoma eye drops.
Mark Prausnitz is director of the Center for Drug Design, Development and Delivery at the Georgia Institute of Technology. He helped develop the microneedles in a joint project with researchers at Emory University. He says the tiny needles are a better way to deliver medicine than an eye dropper.
"What the microneedle enables is a very targeted delivery, to put the drug just in the spot where it needs to be within the eye so that the drug is as effective and potent as possible where the drug needs to act. And the drug doesn't go to other places in the eye where it can cause side effects."
Being able to target the drug means that less medicine is needed. The microneedles are either hollow or empty, like a normal hypodermic needle, or covered with a drug which breaks down in the eye.
Researchers tested the treatment on mice. Mark Prausnitz says the microneedles were successful in treating both glaucoma and the growth of unwanted blood vessels around the cornea. The condition is called corneal neovascularization.
"One was a glaucoma drug where we were able to control the pressure inside of the eye. The other was a drug that stops blood vessel growth. And so when there was abnormal blood vessel growth going into the cornea due to an injury, we were able to administer that drug and suppress the blood vessel growth."
Dr. Prausnitz says some people may find the microneedles uncomfortable despite their size. But he says an anesthetic drug could be used so that a patient does not feel any pain.
The solid needle for treatment of glaucoma is still being tested.
A report on the needle technology was published in the journal Investigative Ophthalmology and Visual Science.
I'm Jonathan Evans.