Techniques used by stargazers to get a clearer picture of the heavens are being harnessed by eye doctors.

"Adaptive optics" is delivering a clear image of individual cells at the back of the eye.

It could help diagnose potentially sight-threatening conditions before the patient has even noticed a problem.

Experts believe that the techniques will become a part of NHS care within the next decade.

It's amazing that we can see at all with the number of aberrations there are at the back of the eye Mr James Morgan, University of Cardiff

When someone looks at a star in the night sky with the naked eye, it often appears to twinkle.

This is distortion caused by temperature changes in the atmosphere - and can play havoc with the readings from powerful telescopes.

Scientists found a way of using powerful computers to compensate for these and give a sharp image.

In a similar way, the cells at the back of the eye are constantly shifting, making it very difficult to get a clear snapshot of particular cells to see whether they are dead, damaged or healthy.

Dead cells

Doctors at the Visual Sciences Group at Indiana University used "adaptive optics" to iron out the distortion caused by these changes, delivering a crystal clear image of the cells.

This allowed them to spot conditions such as glaucoma and age-related macular degeneration by the trail of dead cells they leave in on the retina, the layer at the back of the eye that receives and sends light information.

Professor Larry Thibos, one of the researchers, said: "In glaucoma, for example, the actual disease is cells in the optic nerve dying, and right now doctors can't see that happening.

"They can only see it after the cells are dead. It may take 10 years for changes in vision caused by glaucoma to show up."

New techniques

James Morgan, from the Department of Optometry and Vision Sciences at Cardiff University, told BBC News Online that "adaptive optics" was the "hot topic" in ophthalmology.

He said: "It's amazing that we can see at all with the number of aberrations there are at the back of the eye.

"The technology is able to overcome these and produce a clear view.

"In these diseases, the name of the game is picking them up before they have affected the patient's vision."