File:The student's guide to diseases of the eye (1884) (14778547052).jpg

Identifier: studentsguidetod1884nett (find matches)
Title: The student's guide to diseases of the eye
Year: 1884 (1880s)
Authors: Nettleship, Edward, 1845-1913
Subjects: Eye Color blindness Ophthalmology Ophthalmology Eye Diseases Color Perception Color Vision Defects
Publisher: London : J. & A. Churchill
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
ror of refractionis measured by the lens, which put close to thepatients eye in a case of ametropia, renders themovement, and the other characters, of the imagethe same as in emmetropia. The test is really mostaccurate when used at a great distance from thepatient ; in practice a distance of about 1 m.(100—120 cm., or 3—4) is chosen. Observation isdirected to the boundary line between the lightedand adjacent non-lighted, area, i. e. to the movement orthe dark shadow rather than of the flame-image. Ifthe observer, being at 120 cm. (4) from the patientand using an ordinary concave mirror of 22 cm. (9)focus, throw the light into the patients pupil# andslightly rotate the mirror between the finger andthumb, he will see a dark shadow pass across theilluminated field of the pupil. The edge ot thisshadow has the same direction as the axis on whichthe mirror is turned. In E., H. and very low M. the # The pupil should whenever possible be dilated by atropine. 56 OPHTHALMOSCOPIC EXAMINATION
Text Appearing After Image:
Fig. 36.—Retinoscopy. OPHTHALMOSCOPIC EXAMINATION 57 shadow moves in the direction opposite to that inwhich the mirror is rotated (or against themirror) ; in M. of more than 1 D it moves in thesame direction as the mirror (or with the mirror).The light should be thrown as nearly as possible inthe direction of the visual axis, and the lamp beplaced immediately over the patients head ratherthan to one side. In Fig. 36, 1, the eye e is lighted by the invertedimage of the flame l, formed at i by the mirrorm. Of the image i a second image i, again in-verted, is formed on the fundus of e. i will beaccurately focussed if the eye e is adapted for theimage i, but will be more or less out of focus inevery other case. The observer, placed behind m,sees an image of i formed in the same way as theimage of the fundus seen by the direct method(p. 41), and therefore either inverted and real, orerect and virtual, according as the eye is M or H(p. 51.) If the observers eye be accurately adaptedfor th

Note About Images