Optometrists (ODs) and ophthalmologists (MDs) both practice eye care, but in different, though often overlapping, areas: In the United States, ODs (Doctors of Optometry) examine eyes for both vision and health problems, prescribe eyeglasses, prescribe and fit contact lenses, and treat some eye conditions and diseases. ODs attend four years of optometry school after attaining their BS or BA college degree. MDs are medical doctors who specialize in the eyes. They examine eyes, treat disease, perform surgery, and prescribe glasses and contacts. Like other physicians, they complete a BS or BA degree, attend four years of medical school, and complete a residency program in their practice specialty. Both ODs and MDs often pursue further subspecialty fellowship training, and they take additional continuing education courses during their careers in order to stay up to date and to maintain state and national board certifications. Other non-doctor eye care practitioners include paraoptometrics, contact lens technicians, and opticians, whose training and continuing education requirements can differ depending on the state in which they practice.