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Related to ophthalmoscope: direct ophthalmoscope
ophthalmoscope (ŏfthălˈməskōpˌ), instrument used for examining the inner structure of the eye. The device was invented by the German physiologist H. L. F. von Helmholtz in 1851. His model consisted of three plates of glass pressed together and mounted on a handle at a 45° angle. A light was placed beside the subject whose eyes were to be examined. Some light passed through the plates, but some was reflected back into the eye. The form of the instrument now in general use consists of a concave mirror and a battery-powered light source within a tubular handle. Sighting is through a single or binocular eyepiece. The ophthalmoscope is equipped with a rotating disc of lenses to permit observation of the eye at varying depths and magnifications. Examination of the eye may be enhanced by administering drugs to dilate the pupil.
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An instrument, consisting essentially of a concave mirror with a hole in it and fitted with lenses of different powers, for examining the interior of the eye through the pupil.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
an instrument for examining the interior of the eye
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005