An eye blister is a benign growth which can appear on the whites of the eyes or on the cornea itself. There are two main types of eye blister: pinguecula and pterygium.
Before x ray machines were invented, broken bones, tumors and the location of bullets were all diagnosed by physical examination and a doctor's best guess. Patients paid the price of these approaches. Then on November 8th of 1895, a German physics professor Wilhelm Conrad Roentgen made a remarkable discovery.
Johann Ritter is best known for his discovery of ultraviolet light in 1801. A year earlier, in 1800, William Herschel discovered infrared light. This was the first time that a form of light beyond visible light had been detected.