Implantable corneal inlays to make readers a thing of the past?
A new corneal implant akin to a tiny camera aperture is grabbing public attention after research indicates the device could be an alternative to reading glasses in presbyopes.
Though corneal inlays offer some promise, just like other forms of presbyopic correction, such as glasses and multifocal contact lenses, they have their strengths and drawbacks.
The study—presented at the American Academy of Ophthalmology 2014 annual meeting earlier this month—tracked the efficacy of the KAMRA polyvinylidene fluoride ring at offering subjects improved vision without corrective lenses and without sacrificing distance vision.
Essentially a focusing aperture or artificial pupil, the KAMRA inlay is a 3.8 millimeter (mm) diameter ring with a 1.6 mm hole in the center that is implanted into a small pocket in the cornea to help adjust the eye's depth of field.
Clinicians studied more than 500 presbyopic patients ages 45 to 60 with no nearsightedness for three years after implantation. Reportedly, 83 percent of eyes with the implant could see with 20/40 vision or better over the time period. And on average, patients gained 2.9 lines on a reading chart.
The procedure takes about 10 minutes and requires only topical anesthesia. The inlay also can be removed, unlike in procedures such as LASIK.
The KAMRA device is currently available in several countries worldwide but awaits approval by the U.S. Food & Drug Administration. This product is only one of several similar inlays being developed for the U.S. market.
Concerns of the aging eye
Presbyopia reportedly affects more than 1 billion people globally, and while irreversible, the condition is traditionally compensated for with corrective lenses, such as reading glasses.
When it comes to corneal inlays for correction of presbyopia, Thomas Quinn, O.D., AOA Contact Lens and Cornea Section (CLCS) chair, says these devices have been explored for a number of years, and while promising, still exhibit strengths and drawbacks similar to those of glasses and multifocal contact lenses.
"Their greatest strength is convenience, but drawbacks include some reduction in visual performance in low light, such as during night driving or when reading a menu in a dimly lit restaurant," Dr. Quinn states.
"Also, though it may be relatively safe, any surgical procedure involves some level of risk. However, I welcome any new tools we may employ to improve the quality of life of our presbyopic patients."
To find more information about the care of patients with presbyopia, click here for the AOA member-exclusive clinical care guideline.