FDA Okays Glaucoma Stent For Combo Cataract-Glaucoma Surgery
The Food and Drug Administration (FDA) recently approved the use of iStent, a tiny device designed by Glaukos Corp, for combination cataract and glaucoma surgery. iStent, which is less than one mm long and 0.3 mm high, is the smallest medical device ever approved to be implanted in the human eye—or the human body. The stent is designed to relieve pressure within the eye for patients with open-angle glaucoma, the most prevalent form of glaucoma and the second-leading cause of blindness throughout the world. The iStent may be placed during cataract-removal surgery.
How Does It Work?
Glaucoma, a general name for a group of conditions that injure the optic nerve, affects more than 60 million people throughout the world, and as the world’s elderly population grows, the prevalence of both glaucoma and cataracts are expected to increase.
The most common treatment for open-angle glaucoma is medicated eye drops that help keep eye pressure at safe levels. Although there is no cure for glaucoma, diagnosing the disease at an early stage can help to preserve vision.
Normally, aqueous humor (a clear fluid in the eyes) flows without stopping in and out of the eye’s anterior chamber, a space located between the cornea and iris. Aqueous humor flows from this chamber through a web of tissue called the trabecular meshwork and drains out of the eye. When open-angle glaucoma develops, however, the trabecular meshwork gradually clogs, causing pressure to increase inside the eye and eventually damaging the optic nerve.
The iStent is a miniscule titanium tube that counteracts open-angle glaucoma by creating an opening in the trabecular meshwork through which the aqueous humor can drain.
In the study for FDA approval, 68 percent of patients who received the stent during combination cataract and glaucoma surgery had normal eye pressure one year after surgery without the use of glaucoma medications. This treatment is a cost-effective alternative, as glaucoma eye-drops are often expensive and it is usually difficult for patients to adhere to the eye-drop treatment regimen. The stents may be used at an earlier stage in the development of open-angle glaucoma than other surgical treatments.
Because the study involved implanting the stent at the same time that cataract surgery was performed, researchers were not able to attribute all of the improvements to either the stent or the cataract surgery alone.
An ophthalmologist places the iStent through a tiny incision in the cornea. When the treatment is combined with cataract surgery, the same incision may be used. The iStent can be placed using topical anesthesia alone.
Two forms of the stent are available, one for the right eye and one for the left. The surgeon uses powerful microscopes to visualize the proper placement in the eye.
This miniature new device has the potential to create big positive changes for many patients suffering from a combination of glaucoma and cataracts.