INDIRECT OPHTHALMOSCOPY LENS FOR USE WITH SLIT LAMP BIOMICROSCOPE

摘要

A very strong plus symmetrical double aspheric lens is used as a condensing-image-forming lens for indirect ophthalmoscopy with the slit lamp biomicroscope. The patient is seated at the slit lamp biomicroscope with his head held firmly in position by the chin rest and heat support. The light beam from the slit lamp, with its slit open fully, is directed at the indirect ophthalmoscopy lens of this invention which converges the light beam to an image of the light source at or near the center of the pupil of the eye. The light beam then diverges to illuminate the fundus of the eye. An inverted aerial image of the fundus of the eye is then formed by the lens of this invention of the light emerging from the eye and is viewed monocularly or binocularly and stereoscopically with the binocular biomicroscope of the slit lamp which can magnify the aerial image from 7 to 40 times. The lens of this invention is a small diameter symmetrical double aspheric lens whose coaxial surfaces are of decreasing curvature from the apices peripheralward with the sum of the axial dioptric powers of the front and back surfaces ranging from 60 diopters to 130 diopters. The design of the surfaces of the lens is such that a flat aerial image of the fundus of the eye is formed from the light emerging from the eye in which aerial image the aberrations including field curvature, astigmatism, and distortion are corrected.