Optician, filler of prescriptions for and dispenser of corrective lenses. An optician may grind lenses as instructed by the prescription of an optometrist (see optometry) or ophthalmologist (s...

Cryosurgery, bloodless surgical technique using a supercooled probe to destroy diseased or superfluous tissue. Liquid nitrogen circulating through the instrument cools it to temperatures as lo...

Purkinje, Johannes Evangelista, 1787–1869, Czech physiologist. While professor (1823–50) at the Univ. of Breslau he pioneered in establishing laboratory training in German universities. From 1...

Neurology, study of the morphology, physiology, and pathology of the human nervous system. As researchers, neurologists carry on investigative and experimental work in such areas as conductivi...

Optometry, eye-care specialty concerned with eye examination, determination of visual abilities, diagnosis of eye diseases and conditions, and the prescription of lenses and other corrective m...

Ultrasound or sonography, in medicine, technique that uses sound waves to study and treat hard-to-reach body areas. In scanning with ultrasound, high-frequency sound waves are transmitted to t...