Text-book of ophthalmology . g., at g g. In this case the left halves of both retinae (/ and /i) wouldbe cut off from their connection with the cortex of the left hemisphere. Theright half, G, of the fields of vision of the two eyes would be wanting, so thatonly the left halves of all objects sighted would be seen. In like manner,the left halves of both visual fields would be lost upon destruction of theright opt ic 1 ract. Hemianopia thus originating is called homonymous or lat-eral (Fig. 272). It is called right-sided or left-sided according as the rightor the lefi half of the visual field i
Text-book of ophthalmology . g., at g g. In this case the left halves of both retinae (/ and /i) wouldbe cut off from their connection with the cortex of the left hemisphere. Theright half, G, of the fields of vision of the two eyes would be wanting, so thatonly the left halves of all objects sighted would be seen. In like manner,the left halves of both visual fields would be lost upon destruction of theright opt ic 1 ract. Hemianopia thus originating is called homonymous or lat-eral (Fig. 272). It is called right-sided or left-sided according as the rightor the lefi half of the visual field is wanting. Such a hemiopia would also,of course, occur if the destruction did not affect the optic tract itself, but aBpol placed higher up (e. g., e e)—in fact, even the cerebral cortex hemiopia, therefore, is always indicativeof a lesion which lies 2 Prom rjniirix;, half, and <Li//, vision. By many authors the terms hemianopia or hemianopsia,formed by the Interposition of M a privative, are DISEASES OF THE OPTIC NERVE 613 to the central side of the chiasm and upon the same side as the blind halfof the retina. [But see pages 615, 616.] If the chiasm is divided by a sagittal section (s s, Fig. 269) into a rightand left half, all the decussating fibers are severed, while the non-decussatingbundles remain intact. Since the decussating bundle supplies the innerhalves (I and r{) of the two retinae these portions of the retina would bethrown out of use, and thus the outer temporal half of the two visual fieldswould be suppressed. This form of visual disturbance is therefore calledtemporal (or bitemporal) hemiopia (Fig. 273). It occurs, for instance, whenL B
Size: 1970px × 1268px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjecteye, booksubjectophth
