nd almost all of the cases of
chronic glaucoma of long standing the filtration angle becomes blocked
by the advance of the root of the iris.

_Iris._ In acute glaucoma the iris is congested and thickened. It is
pushed forward and may lie against the cornea at its periphery. When the
attack subsides, the iris falls away from the cornea. Aside from the
congestion, the primary changes that take place in the iris are
indicative of paresis of the fibers of the motor oculi that supply the
sphincter pupillae, and stimulation of the fibers from the sympathetic
producing vasomotor spasm. The long diameter of the pupil apparently
lies in the direction of the terminal vessels of the two principal
branches of each long ciliary artery which form the circulus iridis
major, where the vasomotor spasm would have the greatest effect in
lessening the blood supply. The haziness of the cornea and slight
turbidity of the aqueous contribute greatly to the apparent change in
the color of the iris. In cases of simple chronic glaucoma there is but
little evidence of edema of the iris. If the iris lies in contact with
the sclera and cornea for some time, it becomes adherent (peripheral
anterior synechia). As the disease progresses, the stroma of the iris
atrophies and contracts. There is very little 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
t