The VisionCare telescope is shown balanced on a finger. (Courtesy VisionCare)

A U.S. regulator has approved the use of a small telescope that can be implanted in one eye to help some patients suffering a loss of vision.

Two versions of the implantable miniature telescope can replace the natural lens and provide an image that is magnified by 2.2 or 2.7 times, the Food and Drug Administration said Tuesday.

The telescope magnifies and projects images onto a healthy portion of the retina, but can be used in one eye only; the other eye is needed for peripheral vision.

The device could help some patients suffering from end-stage age-related macular degeneration, a disease related to aging that is a leading cause of vision loss for people over 60.

The telescope is intended for patients 75 and older with severe to profound vision impairment caused by blind spots, the FDA said. Because the brain must merge the views from two eyes into a single image, patients will need rehabilitation after the surgery to make it work, the FDA said.

A clinical test of the telescope involving 219 patients found that 75 per cent had their vision improve from severe or profound impairment to moderate impairment.

Due to the size of the device, implantation can cause other problems, including the need for a corneal transplant, the FDA warned.

The agency and manufacturer VisionCare Ophthalmic Technologies Inc. of Saratoga, Calif., agreed to create detailed labelling to communicate the risks.

And as a condition of approval, VisionCare must conduct two studies, following up existing patients and beginning a study of 770 new patients, the FDA said.

The telescope costs $15,000 US, VisionCare said.

With files from The Associated Press