Scientists have developed implantable eye devices that improve vision and could soon become a viable alternative for ageing eyes.
A corneal inlay device currently undergoing clinical review in the US improved near vision well enough for 80 percent of the participating patients to read a newspaper without disturbing far distance vision needed for daily activities like driving.
One of the devices is the KAMRA inlay - a thin, flexible doughnut-shaped ring that measures 3.8 mm in diameter, with a 1.6 mm 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, researchers reported.
"Corneal inlays represent a great opportunity to improve vision with a safety net of removability," said lead researcher John Vukich, professor in ophthalmology and vision sciences at the University of Wisconsin, Madison in the US.
To test the inlay's efficacy, clinicians conducted a study of 507 patients between the age 45 and 60 across the US, Europe and Asia with the eye condition presbyopia (a condition associated with aging in which the eye exhibits a progressively diminished ability to focus on near objects).
The researchers implanted the ring in the patients and followed up with them over the course of three years.
In 83 percent of eyes with the implant, the KAMRA corneal inlay allowed presbyopic patients to see with 20/40 vision or better over the following three years.
This is considered the standard for being able to read a newspaper or drive a vehicle without corrective lenses.
Presbyopia affects more than one billion people worldwide.
As people age, the cornea becomes less flexible and bends in such a way that it becomes difficult to see up close.
The results were shared at "AAO 2014" - the 118th annual meeting of the American Academy of Ophthalmology.
