'Renewable' eyes? Overcoming aging with bionic implants
Closest focusing distance change with age for a distance corrected eye. Eye focus is measured in dioptres (D) = 1 / focusing distance in meters.
Advanced artificial lenses to replace those contained in our eyes could make age related difficulties with near-vision a thing of the past. Artificial lenses are already used to replace the cloudy lenses of those with cataracts, but these have a fixed focus. The next generation of lenses will be able to change shape or position within the eye in order to focus just like the natural lens.
"Lenses that move forward on hinges on stimulation of the focusing muscles within the eye are already available but not within the NHS," explains James Wolffsohn of Aston University. "The muscles apply pressure to the hinge making the lens move forward to re-focus on objects closer to you." A further system based on springs between two lenses, a little like a mini telescope, is undergoing clinical trials. Using a viscous liquid to refill the capsule in which the natural lens used to sit has also been proposed, but is in the early stages of development.
"One day we might consider replacing the eye's lenses in every person as they reach their mid 40s to restore their eye focus and prevent cataracts forming," says James. "This move could, however, be controversial as you would be performing surgery on an effectively healthy eye, replacing a clear lens, albeit one that needs glasses."