A new device that allows at-home testing for glaucoma, one of the leading causes of blindness around the world, has been designed by a Yale physician.
Dr. M. Marc Abreu says he hopes the Alcon Abreu Tonometry System will improve glaucoma diagnosis and treatment because it enables ophthalmologists to monitor the patient's eye pressure throughout the day and away from the hospital, in addition to the isolated single test in a doctor's office.
"There is the potential to completely change the way glaucoma is treated, diagnosed and monitored," says Abreu, a postdoctoral fellow in the Department of Ophthalmology and Visual Science at the School of Medicine. "The technology allows for a completely automated system without the need for any drops to anesthetize the eye for measurement. And, the whole system is affordable."
Alcon Universal Ltd. of Fort Worth, Texas, the largest ophthalmic company in the world, has signed an exclusive license agreement to manufacture and market the device.
Glaucoma is a disease in which there is elevated pressure in the eye due to obstruction of the outflow of fluid circulating in the anterior and posterior chambers of the eye. The increased pressure can potentially damage the optic nerve, causing visual defects and blindness if left undetected and untreated.
The more common form is known as open-angle, or chronic, glaucoma, which has a genetic component and is one of the leading causes of blindness. There are many other forms of glaucoma, such as angle recession glaucoma, which is caused by blunt trauma to the eye. Also, the use of any type of steroids, including skin ointments, can produce an increase in eye pressure and steroid-induced glaucoma.
The disease progresses slowly over a period of years and because of the gradual and painless loss of vision an individual might not be driven to seek help until irreversible damage has already occurred. As a result, millions of glaucoma victims are unaware that they have the disease and face eventual blindness.
Although glaucoma is more common in adults age 40 and over, it can occur at any age. Glaucoma is on the rise, say researchers, and will continue to mount as the mean age of the population increases. The National Eye Institute estimates there are about 75 million people at risk of developing glaucoma. Early detection and treatment are considered key to preventing blindness. Treatment involves the use of eye drops and, in more severe cases, laser and incisional surgery.
Abreu's device uses disposable contact lenses with a magnetic strip. A separate device, an actuator about the size of a handheld tape recorder, will generate an electromagnetic field that acts on the lens and obtains a measurement.
The system eliminates the problem doctors have detecting peaks in pressure when they do a single test in their office. The measurements can then be transmitted via the Internet to the ophthalmologist studying the case. The device, as designed, will measure the eye pressure in about 0.01 seconds.
Patients with glaucoma can then check their eye pressure as frequently as they want or need to and in the comfort of their homes. "The device is planned to provide the doctor with a whole history of pressure changes when the patient is not in the doctor's office," Abreu says. "Furthermore, the doctor can set the target eye pressure for each patient and, in this way, better monitor treatment."
The system also corrects for another problem. Other devices to measure pressure in the eye require direct contact with the eye, which causes patients to move involuntarily, thereby distorting the accuracy of the reading. The Alcon Abreu Tonometry System will be designed to be quick, soundless and painlesss, and it does not require direct contact of the actuating force with the eye.
The system may also allow for more consistent use of medications by patients since, even after being diagnosed, some patients go blind due to poor compliance. By being more aware of the problem, patients are more likely to use their medications and thus preserve their sight, says Abreu.
The device is currently under development with clinical trials eventually planned to begin in the United States, Canada, Europe and Japan.
Abreu earned his Medical Doctorate from the Paulista School of Medicine at the Federal University of Sao Paulo, Brazil, and completed his ophthalmology residence there as well. He received the prestigious Renato de Toledo prize as outstanding resident in the program.
-- By Jacqueline Weaver
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