File:On the anomalies of accommodation and refraction of the eye, witha preliminary essay on physiological dioptrics (1864) (14783640572).jpg

Identifier: onanomaliesofacc00dond (find matches)
Title: On the anomalies of accommodation and refraction of the eye, witha preliminary essay on physiological dioptrics
Year: 1864 (1860s)
Authors: Donders, F. C. (Franciscus Cornelius), 1818-1889 Moore, translator., William Daniel New Sydenham Society
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Publisher: London : The New Sydenham Society
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yreflexion on the surface of the vitreous humour, not only the apparent,but the actual size diminishes a little in accommodation for nearobjects, and that, consequently, the posterior surface of the lens, too,increases in convexity, although this increase is very slight. As to the change in situation of the curved surfaces of the lens, thiscan be determined from the alteration of place of the reflected images.If we compare Fig. 5, A and B, we shall see that in B the image breflected by the anterior surface of the lens, is approximated muchmore to the reflected image of the cornea a, than in A; and Cramerhence inferred that the anterior surface of the lens, which hadbecome more convex, now comes also to lie closer to the cornea. * Arch. f. Ophthalmologic, herausgegeben von Artl, Donders und vonGraefe, Bd. I. Abth. 2, p. 1. f Monatsberichte der Akademie zu Berlin, Febr. 18.33, p. 137. 14 CHANGE OF THE EYE IN ACCOMMODATION. The next figure (6) clearly decides this. A A is the axis of the
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cornea, with which we here assume that the axis of the lens L FIXITY OF FORM OF THE CORNEA. 15 coincides. The lens is drawn in a double form, namely, with con-tinuous lines in the form of accommodation for distant, and withdotted lines in the form of accommodation for near objects. At fis a flame; at o the eye of the observer. These two are so placedthat lines proceeding from them cut each point of the axis at similarangles. Therefore, the rays thrown back by the reflecting surfacesof the observed eye, where these surfaces an cut by the axis, reach theeye of the observer. The reflected Image of tin cornea is consequently Been in the direc-tion 0 I, and (disregarding refraction on surfaces situated in front) thatof the anl of the leus in the direction O-Z, that of the :ior surface in the direction 08. Projected on the surface I I ,they appear closeto one another as the dline, the second image is s

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