Medical lenses (also known as dental lenses) are designed for use in surgeries and hospital operating theatres, and consist of a macro lens with a focal length between 100 and 200mm with a ring flash built in. They produce excellent results, but are very expensive. In the first models, magnification was adjusted with close-up lenses, and exposure was controlled by using specified combinations of flash power, aperture and magnification. More recent models use a normal focusing mechanism, and the flash exposure is controlled automatically.
They have only been available for a few cameras, including Nikon and Yashica. Olympus marketed a combination of the OM-2N camera, variable extension tube, 135 mm bellows macro lens and T10 ring flash for medical purposes.