Glaucoma | Page 9

evidence
of small-cell infiltration or the formation of cicatrical tissue. Numerous
slits may develop in the iris through which the fundus of the eye may
be seen (polycoria). The pigment layer does not atrophy in proportion
to the stroma of the iris; by the contraction of the stroma of the pigment
layer is doubled upon itself at the pupillary margin, forming a black
ring of greater or less width (ectropian uveae). The iris becomes
attached to the pectinate ligament and to the endothelium of Descemet's
membrane. In a very few cases the closure of the angle is not complete
at the apex, a small space remaining comparatively free for a long time.
The adhesion of the iris to the pectinaform ligament and cornea is not
uniform at all parts of the periphery; it varies in width. Portions of the
iris angle may remain open while other parts are closed. Where the iris
tissue lies in contact with the cornea, the stroma of the iris almost
totally disappears. In some cases the iris becomes totally adherent to
the cornea.

Ciliary Body and Chorioid. In acute glaucoma there is congestion of
the entire uveal tract, the congestion partaking more of a venous stasis
than of an active or arterial congestion. The vessels of the ciliary
process, which are larger and more tortuous in adults of advanced years
than in the young, become enormously distended, causing almost
complete obliteration of the perilental space. They press against the
root of the iris and the equator of the lens, forcing them forward. There
is edema of the ureal tract, apparently from transudation of serum.
Many small, and sometimes rather large hemorrhages may occur. There
is but little small cell infiltration, indicating almost total absence of
what is ordinarily recognized as true inflammation. It is probable that
the secretion from the glandular zone of the ciliary body is increased.
On subsidence of the congestion, as after miotics or iridectomy, the
tissues may return to very nearly a normal condition. The iris recedes
from contact with the ligamentum pectinatum and cornea and the
filtration angle is again open. In some cases the iris becomes adherent
to the head of the ciliary processes and, when atrophy of the ciliary
body occurs, is drawn backward at the base of the iris by the receding
tissues. If the hypertension persists or is repeated at varying periods, a
slow atrophy of the uveal tract sets in. Eventually the ciliary body
becomes very much reduced in thickness, is flattened out, the ciliary
processes reduced in size and the blood vessels disappear or are
reduced much in caliber. Those that persist possess walls that are much
thickened. This is particularly true of hemorrhagic glaucoma.
In advanced absolute glaucoma the chorioid may become reduced to a
very thin membrane consisting of connective tissue and pigmented
cells, scarcely distinguishable even by moderate powers of the
microscope. Atrophy is marked in the vicinity of the venae vorticosae.
Czermak and Birnbacher describe proliferation of the endothelium of
the large veins with contraction and obliteration of their lumen.
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