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.

_Glaucomatous Cup._ The excavation of the disc progresses slowly and is
due in part to stretching the fibers of the lamina cribrosa pressing
this structure outward, and partly to atrophy and disappearance of the
nerve tissue and much of the vascular tissues in the nerve head. The
displacement backward of the lamina cribrosa may cause tha