Every five seconds, someone in the world goes blind. Six million people in the United States are losing or have lost their sight to eye disease, and by 2020, that number is expected to double. But what if doctors could cure blindness? Technology is revealing a whole new world to those who can't see.

For most of us, it's another household chore. For Kathleen Blake, sorting laundry is an accomplishment. At 23, her world started going blurry.

"I started tripping over things, and thought I just needed eyeglasses," Blake said.

Doctors diagnosed her with retinitis pigmentosa -- a hereditary eye disease.

"I just kept thinking 20 years from now, they're going to have a cure for this so I don't need to worry about it," Blake said.

Over the next 15 years, her world went dark. Now she's one of 14 people in the U.S. with a new bionic eye. Doctors implanted an artificial retina into Blake's eye.

"What goes in the eye is a very delicate, saran wrap-type electrode, which then touches the nerve cells and excites them," said Dr. Mark Humayun, an ophthalmologist at the Doheny Eye Institute at the University of Southern California in Los Angeles.

Blake wears a special pair of glasses equipped with a camera. It captures images and converts them into electrical signals that are transmitted wirelessly to the implant. The implant unscrambles the signals, creating a black and white picture. It travels through the optic nerve to Blake's brain.

"Over a period of time, they can recognize large objects like a door, the chair, the table," Humayun said.

While there's still no cure for blindness, technology has given Blake something she's waited 20 years to see.

"I was able to see the fireworks in the sky," Blake said.

The bionic eye is also being studied in patients in Geneva, Paris and London. It is currently being tested on patients with retinitis pigmentosa, but doctors hope it will one day help with other diseases, like macular degeneration.

BACKGROUND: More than 25 million Americans have lost their vision, according to the American Federation for the Blind. Some of the major causes of blindness include cataracts, glaucoma, macular degeneration and retinitis pigmentosa. Researchers may be on the trail of a cure for blindness.

'SEEING' WITH THE MOUTH: The BrainPort is one new technology that's giving the blind hope. The non-surgical visual prosthetic is currently in clinical investigation. Users wear a pair of glasses fitted with a digital video camera. Images from the camera are sent translated into gentle electrical simulation that's read by device placed on the tongue.

Another way vision loss is being treated is with bionic eyes. Dr. Mark Humayun, an ophthalmologist at the University of Southern California in Los Angeles, has developed the Argus II. Patients wear a pair of glasses with a video camera and radio transmitter attached to it. Signals from the camera are sent to a computer on a belt and are translated into electrical impulses. Those impulses are sent inside the eye to an implant placed surgically in the person. Sixty electrodes on the implant read the impulses and then trigger cells inside the eye. The result: The patient can see the outline and shadows of objects.

OTHER SIGHT BREAKTHROUGHS: Modified osteo-odonto-keratprosthesis (MOOKP) is another revolutionary procedure that aims to restore vision by implanting a patient's tooth in the eye to hold a prosthetic lens in place. Tissue bonds to the tooth, merging it with the body. When the eye heals, you are unable to see the tooth inside the eye, as it's covered by multiple layers. The procedure is performed on individuals with Stevens-Johnson syndrome, which is, according to the Mayo Clinic, a rare disorder that causes the skin and mucous membranes to react severely to a medication or an infection.

Researchers in Australia are also working on a simple way to restore sight due to corneal damage: infusing contacts with a patient's own stem cells. So far, study subjects report being able to see after two weeks. Most patients had vision lost in just one eye. so researchers harvested stem cells from their good eye. Two of the three patients went from legally blind to being partially able to read an eye chart. The third patient regained enough sight to pass a driving exam.

Gene therapy is also offering hope. Researchers at the University of Pennsylvania School of Medicine used gene therapy to treat 12 patients with Leber congenital amaurosis (LCA), a serious and rare disease of the eye caused by at least one of 13 possible genetic mutations. All 12 patients' vision was improved from the gene therapy and increased at least 100-fold in constricting of the pupil when exposed to light. In gene therapy, doctors insert genes directly into a patient’s cells and tissue. To treat the patients, a virus carrying the genetic mutation was injected into the eye with the worst vision.