. Pathology and bacteriology [electronic resource]. Ophthalmology; Eye; Eye; Bacteriology; Ophthalmology; Eye; Bacteriology; Eye. 636 DEGENERATIONS traumatism, insufficient blood supply, toxic substances, increased intra-ocular tension, or abiotrophy. As the majority of the fibres of the optic nerve are axons of the ganglion cells of the retina, degeneration of the former necessarily entails atrophy of the latter. It has been shown experimentally in animals,^ that a wound of the retina results in the degeneration of a cor- responding tract of fibres in the optic nerve. The changes which take p
. Pathology and bacteriology [electronic resource]. Ophthalmology; Eye; Eye; Bacteriology; Ophthalmology; Eye; Bacteriology; Eye. 636 DEGENERATIONS traumatism, insufficient blood supply, toxic substances, increased intra-ocular tension, or abiotrophy. As the majority of the fibres of the optic nerve are axons of the ganglion cells of the retina, degeneration of the former necessarily entails atrophy of the latter. It has been shown experimentally in animals,^ that a wound of the retina results in the degeneration of a cor- responding tract of fibres in the optic nerve. The changes which take place in the optic nerve from degeneration of the neurons in the retina are well demon- FiG. 280.—Section through the head of the optic nerve in a case of simple optic atrophy. Note the reduction in the size of the nerves, and that a depression has formed on the inner surface of the lamina cribrosa in the position normally occupied by the optic papilla. strated by Marchi's method of staining (see page 706). As the atrophic process proceeds, the medullary sheaths break up into rows of globules along the whole course of the affected fibres. They are then slowly carried away either in the lymph stream or absorbed by leucocytes. The axis cylinders become beaded, then broken up, and finally disap- pear. As the nerve fibres become destroyed spaces are left in the supporting connective tissue framework, some proliferation of the neuroglia may take place, but the size of the nerve tends to become considerably reduced (Fig. 280). Atrophy of the optic papilla secondary to papillitis or papilledema can be distinguished clinically from simple atrophy by the presence of newl}^ formed tissue on the disc, 1 Usher and Dean. Trans. Ophth. Soc. of the U. K., XVI, 1896, Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Co
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