Glaucoma has been in the news lately, for reasons both good and bad. The eye condition has been linked to the Zika virus, and the FDA has approved a new treatment. Read on to learn more about the latest developments in glaucoma treatments and research.
What is glaucoma?
“Glaucoma is a disease of the optic nerve which connects the eye to the brain and brings the images from the retina of the eye to the brain where we ‘see,’” says Thomas Brunner, President and CEO of the Glaucoma Research Foundation (GRF). Because there isn’t a way to restore or regenerate the optic nerve, blindness from glaucoma is the largest irreversible cause of blindness in the world, he adds.
There’s no cure, but it’s possible to halt further loss of vision with the help of medication and/or surgery. Everyone is at risk, but older people tend to be the most affected. African Americans, Asians, and Latinos have a higher prevalence of the disease. The most common form of glaucoma is open-angle glaucoma, which has no symptoms. As Brunner explains, vision loss normally starts from the side or peripheral vision, so it isn’t noticed. Someone can lose as much as 40 percent of their vision without realizing it because the brain fills in the missing vision. He says regular eye exams are necessary in order to detect glaucoma before there is permanent vision loss, as well as to test for other possible eye problems. A complete eye exam includes five common tests for glaucoma.
The only treatment for glaucoma today is to reduce the fluid pressure inside the eye, says Brunner. For most people, eye drops or an office laser procedure can control this pressure and preserve vision, while surgery may be necessary in more advanced cases.
New developments allow doctors to be more effective in managing glaucoma, says Brunner, who describes tiny implants that help to lower pressure by shunting fluid across tissue, which may block the normal outflow pathways. Another new product is “a device that can continuously deliver a very small amount of medication to the eye instead of once a day eye drops, which can be difficult to get into the eye and are sometimes forgotten,” he says. Some people with glaucoma put drops in their eyes four times a day.
There also new medications to lower eye pressure with fewer side effects or when other medications are no longer effective, says Brunner. “Several new glaucoma medications are expected to become available in 2017 and will benefit patients by helping them to more effectively manage their eye pressure,” he says.
According to the GRF, medical device companies are developing new surgical options, with each approach taking advantage of a specific strategy to reduce eye pressure. As the organization explains on its website, because glaucoma has a slow progression, it’s difficult to gauge the effectiveness of any new intervention. Another challenge is that the most common surgeries have some potentially hazardous outcomes. Therefore, the long-term effectiveness is unknown.
Three new surgical approaches, as described by the GRF are:
• Ex-Press mini glaucoma shunt – can be used with conventional techniques to standardize the operation
• Trabectome – device that removes tissue with an electro-surgical handpiece
• Canaloplasty – dilates the entrance to the outflow pathways in the wall of the eye and constructs an artificial fluid outflow mechanism within the eye wall to reduce pressure
Standard glaucoma surgeries are considered major, but a new group of operations referred to as MIGS, or minimally invasive glaucoma surgery, have been developed in the past few years to reduce some of the complications. Microscopic-sized equipment and tiny incisions are the hallmark of these procedures. Some examples provided by the GRF include:
• Microtrabeculectomies – microscopic-sized tubes inserted into the eye to drain fluid
• Trabecular surgery – a tiny device is inserted into the eye through a tiny incision under high power microscopic control; most useful in early to moderate stages of glaucoma
• Suprachoroidal shunts – tiny tubes with very small internal openings are used to connect the front of the eye to drain fluid; successfully completed US trials and currently under FDA consideration – may be available by late 2016
• New laser procedures – have proven useful before the glaucoma is too advanced
When surgery and medications aren’t effective for refractory glaucoma, there is a new surgical option that was recently approved by the FDA. Called the Xen Glaucoma Treatment System, it’s a gel stent and injector combination that’s implanted through an incision in the cornea. This will be launched in the U.S. early next year.
“Perhaps the most exciting research in glaucoma is directed toward vision restoration,” says Brunner. “New research suggests that it may be possible to restore lost vision by saving the damaged optic nerve or even replacing it with a new one.” He admits this sounds like science fiction, but scientists have been able to do this in laboratory tests. While it’ll be many years before this research results in human benefit, this is promising news, he says.
Clinical trials are being conducted on regenerative medicines like topical eyedrops, injections, or surgical implants. If glaucoma medication could be given only once or twice a year, it would be more effective, says the GRF, so this is one area of research. “Several agents could be placed on or in the eye, including long-lasting drugs that lower eye pressure, or modified virus particles that put new genes inside the eye cells to slow glaucoma damage,” says the GRF.
Researchers at Queen’s University Belfast – together with University of St. Andrews and Aberdeen – have found that a procedure used to remove cataracts is actually more successful than current standard treatments with laser in treating a form of glaucoma. Patients who had this procedure — called clear lens extraction surgery — had better quality of life and vision, with lower eye pressure. They didn’t need as many eye drops to control glaucoma. The procedure is also more cost efficient.
Brunner says other areas of glaucoma research include the use of gene therapy to target genetic mutations leading to glaucoma by replacing or repairing the defective gene and the use of stem cells to replace damaged tissue with new cells. “Again there are promising results in the laboratory and even to treat some rare forms of vision loss,” he says, “but there is still a great deal of work to be done to prove the safety and effectiveness for glaucoma.”