Cataracts - Blinding Flashes

That goal is many years away, though. First, "we have to understand the details - the genes and proteins and molecular pathways involved," says Eleanor Blakely, a scientist at the Lawrence Berkeley National Laboratory (LBNL). Supported by a NASA grant, she and her colleagues are experimenting with human eye tissue to learn these details.

"For good vision, the lens of the eye must be crystal clear," she says. The lens, shaped like an M&M, sits in the opening of the eye and focuses incoming light onto the retina. "At the center of the lens are transparent cells called 'fiber cells.' Damage to the lens can lead to clouding of the fiber cells, and this change in clarity is called a cataract."

more Anatomy of the human eye.

In a healthy human eye, new fiber cells are constantly manufactured to replace old ones. The process begins with "epithelial cells," a type of stem cell that coats the front of the lens. When needed, epithelial cells flatten out and shed their nucleuses and other internal structures to become transparent fiber cells. It's an amazing metamorphosis. "During the final stages," she says, "all of the cell's organelles are disposed of by the cell in a carefully orchestrated process that leaves the cell alive, but basically a bag of crystalline proteins."

Blakely's group has shown that a radiation dose can upset the metamorphosis of epithelial cells, interfering with the formation of fresh fiber cells that make up the body of the lens.

They didn't deliberately irradiate people's eyes to figure this out, of course. Instead, they cultured human epithelial cells in petri dishes. As some of the cells were beginning to turn into fiber cells, her team exposed the cells to controlled doses of radiation. This work was done at LBNL and at the NASA Space Radiation Laboratory at the Brookhaven National Laboratory in Long Island, New York. Afterward, they used modern genetics tools to find out how the cells' genes and proteins responded.