Washington: Glasses may soon be a thing of the past as corneal inlays, implanted into the eye with a simple surgery, can correct vision without the need for corrective treatments, scientists say.
A thin ring which is inserted into the eye could offer a reading glasses-free remedy for presbyopia, the blurriness in near vision experienced by many people over the age of 40, according to a new study.
The corneal inlay device undergoing clinical review in the US improved near vision well enough for 80 per cent of the participating patients to read a newspaper without disturbing far distance vision needed for daily activities like driving.
Researchers said presbyopia affects more than 1 billion people worldwide. As they age, the cornea becomes less flexible and bends in such a way that it becomes difficult to see up close.
While the most common remedy is wearing reading glasses, a host of new corneal inlay products are in development to treat the condition, with three types currently under review by the US Food and Drug Administration (FDA).
The theoretical advantage of using corneal inlays over wearing reading glasses is that corneal inlays prevent the need for constantly putting on and taking off glasses, depending on whether the person needs to see near or far.
One of the devices is the KAMRA inlay, a thin, flexible doughnut-shaped ring that measures 3.8 millimetres in diameter, with a 1.6 millimetre hole in the middle.
When dropped into a small pocket in the cornea covering the front of the eye, the device acts like a camera aperture, adjusting the depth of field so that the viewer can see near and far.
The procedure to insert the implant is relatively quick, lasting about 10 minutes, and requires only topical anaesthesia.
To test the inlay's efficacy, clinicians conducted a prospective non-randomised study of 507 patients between 45 and 60 years of age across the US, Europe and Asia with presbyopia who were not nearsighted.
The researchers implanted the ring in the patients and followed up with them over the course of three years. In 83 per cent of eyes with the implant, the KAMRA corneal inlay allowed presbyopic patients to see with 20/40 vision or better over the three years.
This is considered the standard for being able to read a newspaper or drive a vehicle without corrective lenses. On average, patients gained 2.9 lines on a reading chart. The researchers report that the results remained steady over a three-year period.
Complications from corneal inlays in general have included haziness that is treatable with steroids; however, improvements in inlay design have made the effect less common.
"This is a solution that truly delivers near vision that transitions smoothly to far distance vision," said John Vukich, a clinical adjunct professor in ophthalmology and vision sciences at the University of Wisconsin, Madison.