A researcher who turned cataract surgery into a brief outpatient procedure and three scientists who illuminated how some hormones and vitamins act on the body's cells have won prestigious medical awards. The $50,000 prizes, from the Albert and Mary Lasker Foundation, will be presented Friday.

The award for clinical research will be given posthumously to Charles Kelman, who made cataract removal an outpatient procedure. Previously, cataract operations were risky ordeals that required more than a week of hospitalization with the patient's head immobilized by sandbags.

Kelman began his research in the 1960s as a staff ophthalmologist at the Manhattan Eye, Ear and Throat Hospital in New York. Inspired by an ultrasonic tool his dentist used, he developed a device to pulverize the lens of the eye so it could be removed through a tiny opening.

By 1985 about 15 percent of cataract removals in the United States were done with his technique; by 1996 it was 97 percent. It is now the most frequently performed surgery in many Western countries, the foundation said.

Kelman died in June at age 74. In his memory, the prize's honorarium will go to the International Retinal Research Foundation.

The Lasker award for basic research will be shared by Pierre Chambon of the Institute of Genetics and Molecular and Cellular Biology in Strasbourg, France; Ronald Evans of the Salk Institute for Biological Studies in La Jolla, Calif., and Elwood Jensen of the University of Chicago.

The three men, starting with Jensen in the 1950s and continuing with Chambon and Evans in the 1980s, opened up the field of studying proteins called nuclear hormone receptors, the foundation said. These receptors grab onto certain hormones and vitamins and migrate to the nucleus of a cell, where they regulate the activity of genes.

Such receptors are the targets of some diabetes and cholesterol-lowering drugs, and scientists are still working out the roles of the dozens of known nuclear receptors, with implications for developing new medicines, the foundation said.

Jensen found that a breast cancer's response to certain treatments, including the drug tamoxifen, could be predicted by assessing its supply of estrogen receptors. "His work has transformed the treatment of breast cancer patients and saves or prolongs more than 100,000 lives annually," the Lasker foundation said.

Chambon and Evans, in 1986, independently identified a receptor for retinoic acid, a form of Vitamin A, a key step in studying Vitamin A biology.

The Lasker foundation will also present a $25,000 award for special achievement in medical science to Matthew Meselson of Harvard University. The award honors his discoveries about DNA and his leadership in public policy aimed at eliminating chemical and biological weapons.