To improve near vision and reduce dependence on bifocals or reading glasses, researchers have been looking for other ways to treat presbyopia, the loss of near vision that comes when the natural lens of the eye stiffens over time and the eye muscles can no longer bend the lens to focus on objects nearby.
One recently developed alternative to reading glasses is a corneal inlay. A corneal inlay works a bit like bifocal contact lenses, but instead of sitting on the eye’s surface, the tiny disc is implanted just below the surface. The inlay is surgically implanted in one eye only. It remains there indefinitely and doesn’t have to be removed for cleaning or sterilization.
“If you can’t read the newspaper or your cell phone and you’re picking up reading glasses all the time, this is something you might think about,” says Daniel Durrie, M.D., an ophthalmologist in Overland Park, Kansas, who has been testing the inlays for a decade.
Who can get corneal inlays?
Corneal inlays work best for people who have good distance vision and whose eyes are otherwise healthy. An inlay isn’t recommended for anyone with an eye infection, corneal disease, or certain active autoimmune conditions, such as lupus or rheumatoid arthritis.
Individuals who need glasses or contacts to see objects far away can use an inlay, but they may need additional procedures such as LASIK surgery, in which the cornea is permanently sculpted for distance vision. In addition, your eyes may change as you age and require further surgery.
The KAMRA is for people 45 to 60 who haven’t had cataract surgery and who don’t have severe dry eye. It consists of a tiny opaque ring less than a quarter the size of a typical contact lens, made of a type of plastic, with microscopic holes through which fluids, nutrients and oxygen can flow. It improves near vision by blocking peripheral light rays while allowing central light rays to pass through.
The KAMRA inlay can cause dry eye and vision problems such as glare, halos, poor night vision, or blurry vision, or lead to infection, so you’ll need to discuss with your doctor whether this device is appropriate for you.
The Raindrop, for people 41 to 65 years old, is a small clear disc about half as thick as a human hair that is made of hydrogel, a type of plastic that can absorb water. The implant changes the shape of the cornea so that it focuses light before it reaches the eye’s natural lens; it allows the center of the cornea to focus on near vision, the edge to focuses on distance vision, and the area in between to focus on intermediate vision.
Implantation of the Raindrop may cause such problems as dry eye; decreased vision; clouding, thinning, scarring, or inflammation of the cornea; eye infection; and the need for further eye surgery, such as removal or replacement of the inlay. Again, discuss with your doctor whether this device is right for you.
In recent studies on the two corneal inlays, both improved the near and intermediate vision in the average eye. One small Austrian study, in the February 2015 issue of the Journal of Cataract and Refractive Surgery followed the KAMRA in 32 patients, ages 45 to 55, with good distance vision of at least 20/20 in both eyes. The average near vision in the eyes with the inlays improved from 20/63 before the operation to 20/20 after one year, then decreased to 20/32 five years later.
While some patients had minor problems, such as the inlays slipping and needing recentering, roughly 84 percent said they would have the procedure again, about 6 percent said they wouldn’t, and 10 percent were undecided. The Raindrop has had similar results.
How it’s done
The procedure for the two implants is similar. After applying an anesthetic to the eye, the surgeon uses a laser to create a flap or pocket in the cornea, then inserts the inlay. The cornea heals over the inlay.
Currently, insurance doesn’t cover the cost, which ranges from about $4,000 to $7,000. The surgery takes only about 10 minutes and is normally painless, says Dr. Durrie. Patients take antibiotics and apply anti-inflammatory eyedrops for three months.
The inlays may not eliminate the need for reading glasses in challenging circumstances, such as low light, and some people experience halos or decreased night vision in the first few months. But anyone who is dissatisfied can have an inlay removed.
More options are in the works. A third inlay, the Flexivue Microlens by Presbia, is already on the market in Europe and is moving toward approval in the United States, and an ophthalmologist in India is developing a technique for implanting corneal inlays made from human tissue.
Learn more about vision changes that can affect driving.
Laird Harrison writes about science and medicine. His work has appeared magazines (TIME, Audubon, Discover, Men’s Fitness, Health), newspapers (San Francisco Chronicle, Chicago Tribune, Detroit Free Press); and Web sites (Salon, Reuters, MSNBC, CNN.com). He has produced video for Web sites including Smithsonianmag.com and audio for KQED and WUNC public media stations. His recent novel, Fallen Lake, tells the story of a powerful attraction between two couples and how it affected their children. Harrison has taught writing at San Francisco State University, UC Berkeley Extension and Mediabistro. He grew up in Berkeley, California, and studied creative writing and politics at the University of California, Santa Cruz. He lives in Oakland, California.