BETHESDA, Md. - A new early-detection device for cataracts is helping save patients' sight before it's too late.

Cataracts cause blurring of the eye's lens, and if not caught early enough, can lead to blindness.

Peggy Walker is one of the millions of Americans developed a cataract in one eye.

This is what the world looked like to her. The condition started to affect her daily life.

"With the growth of the cataract, my night vision got worse and worse," Walker said.

Surgery to replace the cataract lens fixed her vision, but she's at risk of developing a cataract in her other eye.

Now, ophthalmologists at the National Institutes of Health have a new device that catches cataracts before vision problems start.

Cataracts form when proteins in the eye clump together and cloud the lens. Risk factors include smoking, diabetes and sun exposure.

According to Dr Manuel B Datiles, III, an ophthalmologist, the new test offers doctors a chance to look for signs of cataracts formation.

"It's an early alarm system," he said. "We actually detect the changes in proteins in the eye before they start clumping together, causing clouding of the lens."

The device uses a low power, safe, laser light called Dynamic Light Scattering, or DLS.

Shining the laser into the eye, the light identifies damaged proteins in the eye, revealing to doctors early telltale signs of cataract formation.

"If you start depleting this protein, then you start developing a cataract," said Dr. Datiles.

The device is being used in clinical trials at Johns Hopkins University and allows for easier testing of medications that might prevent or slow down cataract formation.

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