The leading cause of blindness in the elderly is a progressive eye disease called macular degeneration, which in its most serious, or "wet," form is caused by abnormal blood vessel growth and subsequent blood leakage in the eye. Current treatments use lasers or light-activated drugs to clot these vessels but are generally ineffective; fewer than 3 percent of patients show improved vision following treatment. But in an emerging area of biotechnology, a small New York City company believes it sees a better approach. The key is a biomolecule that stops blood vessels from growing. Injected into the eye, a short piece of artificial RNA, called an aptamer, sticks to proteins that cause abnormal blood vessel growth and inactivates them.

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