File:Text-book of ophthalmology (1919) (14781266252).jpg

Identifier: textbookofophtha1919fuch (find matches)
Title: Text-book of ophthalmology
Year: 1919 (1910s)
Authors: Fuchs, Hofrat Ernst, 1851- Duane, A. (Alexander), b. 1858, tr
Subjects: Ophthalmology Eye Ophthalmology Eye Diseases
Publisher: Philadelphia & London : Lippincott
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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sk begins at the temporalside of the latter in the form of a narrow light-colored crescent (distraction crescent,called conus by Jager, Fig. 200 A, ab). This is accounted for by Stilling as being dueto the displacement of the optic nerve-head toward the temporal side. As such crescentsoften occur in emmetropic eyes, their mode of development has already been consideredon page 96. In near-sighted eyes the displacement of the optic nerve occurs muchmore regularly and to a much greater extent. As the wall of the sclerotico-chorioidalcanal is pulled away from the optic nerve on the temporal side, the sclera and chorioidare pulled up over the nerve to a like degree on the nasal side (Fig. 200, cd). At thenasal side the optic nerve shows through the sclera and chorioid, and hence with theophthalmoscope we see along the nasal border of the papilla a somewhat hazy yellowishcrescent (supertraction crescent—Weiss). With the displacement of the walls of the 460 TEXT-BOOK OF OPHTHALMOLOGY . Aj-
Text Appearing After Image:
ar p v \ du7 ar Fig. 200.—Optic-nerve Entrance in Myopia. A. Ophthalmoscopic Image op the Papilla.—The papilla, 6-c, is of the shape of an ellipse withits long axis vertical. In its outer half it shows the large physiological excavation, upon whose floorare visible the gray stipplings of the lamina cribrosa, while the central vessels ascend on the inner wallof the excavation. Adjoining the outer border of the papilla and not sharply separated from it is thebright crescent, a-b (distraction crescent). This is of a white color, while the papilla itself is reddish.The crescent is covered with brownish, elongated markings, representing remains of the stroma pig-ment of the chorioid. The temporal border of the crescent is sharply defined, and the chorioid adjoin-ing it is somewhat more pigmented than usual. On the other hand, the chorioid in the vicinity of thenasal border of the papilla shows a somewhat lighter coloration in the space between c and d, so that ayellowish crescent, whic

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