Final answer:
Patricia Bath specialized in ophthalmology, specifically inventing a method for cataract surgery that greatly improved eye health and public health efforts.
Step-by-step explanation:
The field of study of Patricia Bath was ophthalmology, a branch of medicine. Dr. Bath was a pioneering ophthalmologist and the inventor of the Laserphaco Probe for cataract treatment. Her extensive research and medical practices revolutionized the way eye surgeries are conducted and helped restore sight to patients who had been blind for decades. Bath's work made significant contributions to the fields of ophthalmology, laser surgery, and public health, and she was also an advocate for combating blindness through public health and community outreach.