_Optic Nerve and Retina._ In the acute form the retina and optic nerve present the same condition that is present in the vascular tunic; namely, that of venous stasis with the consequent edema. Frequently minute hemorrhages occur in the retina, particularly in violent acute attacks. Cupping of the discs slowly develops, causing more or less stretching of the nerve fibers over the edge of the cup. The gradual diminution of the field of vision is due in greater part to death of peripheral nervous elements of the retina, those parts of the field farthest removed from the large arterial trunks suffering first. The arrangement of the arteries at the disc, passing out as they do from the nasal side, of necessity make the vessels that pass to the temporal part of the retina longest and of less caliber. These vessels and their terminals are first to suffer marked diminution in size; death of the perceptive elements supplied with nutrition by these vessels follows. For this reason the nasal part of the field of vision is more often the first to disappear. In congestive (inflammatory) glaucoma, the typical field of vision shows most marked contraction on the nasal side. The disturbance of the nutrition of the retina accounts in greater part for the various forms of visual field met with. Death of all of the perceptive elements of the retina eventually occurs. The loss of nutrition is apparently not the whole cause of blindness. Atrophy of the nerve fibers follows death of retinal neurons, but atrophy of some of the nerve fibers may be, and probably is, due to the pressure and traction exerted upon them at the margin of the disc. It is probable that too much importance has been given to this mode of interference with the nerve fibers. However, the change in the position of the lamina cribrosa must exert a deleterious effect, particularly on those fibers which pass through the peripheral meshes, the shape of which must necessarily be much distorted. In glaucoma simplex, which is largely devoid of marked congestive periods (acute attacks), a surprisingly high degree of acuity of vision may exist with a deep excavation and pale nerve. Careful studies of the retinal vessels in glaucoma (Verhoeff Arch. of Ophth. XLII. p. 145; Opin. Soc. Francaise d'Ophth. 1908) disclose the fact that an increase in the elastic tissue and connective tissue elements occurs in _some cases_, also proliferation of the endothelial cells, which serve to irregularly narrow and, in some instances, obliterate the lumen of the vessel. Arteries and veins are both affected. Hyaline degeneration of the media also occurs. The process is not uniform.