Clinical lectures on some of the principal diseases of the eye. Cataract, continued / by Isidor Glück.

  • Glück, Isidor.
Date:
[1854]
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Licence: Public Domain Mark

Credit: Clinical lectures on some of the principal diseases of the eye. Cataract, continued / by Isidor Glück. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    CLINICAL LECTURES ON SOME OF THE PEIMCIPAL DISEASES OP THE EYE. BY ISIDOR GLUCK, M. D., COR. FEE. MED. SOC. OF LONDON. [From tbe American Medical Monthly, July, 1854.] CATARACT.— Continued. Gentlemen ! The Eye Speculum, or Ophthalmoscope, is an illuminating instrument which serves for examining the illuminated interior parts of the eye, and thus distinctly shows organic changes of the aqueous humor, of the lens and its capsule, of the vitreous humor, the retina, and choroidea, when unobservable by the naked eye. The necessity of such an instrument is obvious, if we reflect that the retina is almost entirely concealed from view to the naked eye. Various contrivances and modifications of them have been introduced for this purpose. Helmholtz devised this speculum, wliich consists, as you observe, of re- Jlectors, to illuminate the retina, and a concave lens, to bring its structure within our focus of vision. The reflectors are four parallel and well-pol- ished slips of glass, which are fixed close by an open frame, which is fas- tened down by screws to the sides of a short square tube. One end of the tube is cut obhquely to form an angle of 56° with the base or other end. The exterior is bronzed, the interior lined with black velvet. A diaphrag-m and a biconcave lens. No. 12, are placed at the base, and secured by a hol- low eye-piece, which can be screwed ofif and on so as to allow the lenses to be changed. Method of using it.—The patient should be seated in a dark room ; a good oil or gas lamp should be placed on his side, on a level with his eyes. The reflectors must be turned towards the eye to be examined (the pupil should be dilated by atropine), and must be adjusted so as to throw the light in the direction of the axis of the instrument on the eye to be ob- served. The observer, having closed one eye, looks through the biconcave lens, and is thus enabled to see the interior of the eye illuminated. The rays of light, on leaving the convex surface of the cornea, are convergent; but the observer’s eye can only bring to a focus slightly convergent or par- allel rays; the neces.sity, therefore, for interposing a concave lens in order to disperse the rays before entering the observer’s qyejTSIaviHentr 'lBy'SQpie ^ T- V 'pis T t- J A • * U f