Patricia E. Bath, an ophthalmologist who took a special interest in combating preventable blindness in underserved populations and along the way became the first black female doctor to receive a medical patent — for a laser technique for treating cataracts — died on Thursday in San Francisco. She was 76.

Her daughter, Eraka Bath, said Dr. Bath had died after a brief illness.

Dr. Bath was an educator and researcher as well as a physician. She began her medical career in New York and in 1974 joined the faculties of the University of California, Los Angeles, and the Charles R. Drew University of Medicine and Science in that city.

When she was just out of medical school, working as an intern at Harlem Hospital and then at an eye clinic at Columbia University, she noticed discrepancies in vision problems between the largely black patient population at Harlem and the largely white one at Columbia. Her observations led her to document that blindness was twice as prevalent among black people as among white people — findings that instilled in her a lifelong commitment to bringing quality eye care to those who might not otherwise have access to it.

In the early 1980s, her work with cataract patients and related research led her to envision a method of using laser technology to remove cataracts, which cloud the lens of the eye.