Invention: Vision amplifier

The number of people suffering seriously impaired vision due to damaged retinas is increasing in the developed world, as populations age and diabetes becomes more common. The search for a technological solution to the problem has led to growing interest in "bionic eyes".

Devices developed so far have usually involved installing a silicon chip into the eye to electrically stimulate the retina's nerves in response to light. Some impressive results have been achieved in this way, but implanted chips do have drawbacks.

Their relatively large size means they block light that would have fallen on healthy parts of the retina and they can also cause tissue damage, such as tearing.

So Jeffrey Olsen at the University of Colorado Hospital has come up with another method entirely – amplifying the light that reaches the retina using the eye's still functioning light-sensitive cells.

Seeing dots

Light amplification could be achieved by implanting quantum dots – nanoscale specks of semiconductor – into the retina, he says. These fluoresce when hit by photons and would have the effect of making any received retinal image brighter.

Quantum dots have several advantages: they require no external power source, are much smaller than silicon chips, and can be coated with a bioactive material that causes them to become lodged in only specific tissues in the retina.

Tests on rats have shown this approach works, the patent application says. Rats that had quantum dots injected into their retinas afterwards had more electrical activity in their retinas than those that received control injections of saline, or no treatment at all.