Text-book of ophthalmology . is not the case until late in life (in the sixthdecade or later). [In some cases of retinitis pigmentosa the main disturbance of sight, especially forreading, is caused by a cortical cataract. The densest part of this lenticular opacitylies righl in the center of the pupillary area, and hence these patients see worst whenthe pupil is contracted, i. e., in a strong light. They therefore form an exception to therule thai persons with retinitis pigmentosa see worst when the illumination is cases can be recognized by the fact that dilatation of the pupil
Text-book of ophthalmology . is not the case until late in life (in the sixthdecade or later). [In some cases of retinitis pigmentosa the main disturbance of sight, especially forreading, is caused by a cortical cataract. The densest part of this lenticular opacitylies righl in the center of the pupillary area, and hence these patients see worst whenthe pupil is contracted, i. e., in a strong light. They therefore form an exception to therule thai persons with retinitis pigmentosa see worst when the illumination is cases can be recognized by the fact that dilatation of the pupil with atropine orhomatropine enhances considerably their ability to read.—D.] 528. Ophthalmoscopic examination shows, as the most prominentsymptom of the disease, the presence of small black spots in the retina(speckled retina, Fig. 258). These are of branched shape, so that theyhave been compared to bone corpuscles or spiders; they are connected withone another by their processes, and are found especially along the DISEASES OF THE RETINA 587 In the beginning of the disease they occupy only the most anterior portion(periphery) of the visible fundus corresponding to the equatorial region ofthe eyeball, but as time goes on, new spots keep forming farther and fartherback, until at length they reach the macula lutea and the papilla. As fastas the retina becomes pigmented, the pigment epithelium becomes decolor-ized, so that the chorioidal vessels getto be more and more visible. Withthe increasing pigmentation of the re-tina the signs of atrophy of the retinaand the papilla become more and moreprominent. Accordingly, what takesplace is a gradual degeneration of theretina associated with a migration of Ppigment from the pigment epithelium through the retina. Magnified i7ox 1. / rk r\\ mi 1 ^ne retina i,s bounded on its anterior sur- intO the retina (Fig. 259). 1 he degen- face by the membrana limitans interna, i, upon .its posterior surface by the membrana limitans eration b
Size: 2104px × 1187px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjecteye, booksubjectophth
