A notable advance in the treatment of vision loss offers hope to patients who've lost their eyesight to certain diseases.

When Constance Schoeman was 28-years-old she developed an eye disease that eventually stole her sight.

"I have retinitis pigmentosa, which is a deterioration of the retina," she says.

Now Constance is trying out an artificial retina that doctors at the University of Southern California implanted in her eye.

Dr. Mark Humayan, with USC's Doheny Eye Institute says, "Given that there's so many patients who are blind because the light sensing cells in the retina don't work, we thought of developing a retinal prosthesis."

The retina is the lining in the back of the eye that sends visual images to the brain. The prosthesis takes over the job if the retina is damaged.

"In essence, what this prosthesis does is take a blind person and hook them up to a camera," Dr. Humayan says.

The tiny camera, hidden in a pair of glasses, captures visual information and then sends it through a cable to tiny electrodes implanted behind the ear.

Dr. Humayan says, "These electrodes then jump-start electrically through tiny pulses the remaining cells in the eye and send this information to the brain."

So far, doctors say the artificial retina shows real promise.

"Our patients, with the model one, can differentiate between a cup, a plate and a knife," says Dr. Humayan.

Constance says, "Maybe it doesn't sound like a lot to some people. But to me it sounds like a whole lot."

Doctors are testing the prosthesis on patients with retinitis pigmentosa and macular degeneration.

The Doheny Eye Institute at the University of Southern California is in charge of the study.