spite of
the fact that a greater force is operating to drive fluid out of the
eye. In his recent tonometric studies Schoenberg noted that under
manipulation the glaucomatous eye softened more slowly than the normal
eye; and suggests this diminished drainage as an important evidence of
glaucoma.

Obstructed outflow might begin in an abnormal tendency of the tissues to
retain fluid, a tendency that Fischer might locate in the colloids. The
increase of intra-ocular pressure noted in cases of uveal inflammation,
to be presently referred to, may be due to some such tendency. But it is
rational to ascribe to obstruction of the filtration angle of the
anterior chamber, the important part it has been supposed to play in the
pathology of glaucoma. However this obstruction may be brought about,
whether by thickening of the iris root during dilatation of the pupil,
pushing forward of the iris root by the larger ciliary processes of age,
or the enlarged crystalline lens pressing on the ciliary processes; or
by inflammatory adhesion of the iris to the filtration area; ballooning
of the iris, or its displacement by traumatic cataract; or adhesion to
the cornea after perforating ulcer in the secondary glaucomas; or
whether the obstruction is due to the accumulation of experimental
precipitates, as shown by Schreiber and Wengler, or possibly of pigment
granules into Fontana's space; or a process of sclerosis closing the
spaces by contraction of new-formed connective tissue, or the covering
over with proliferating implanted epithelium following injury opening
the anterior chamber; glaucoma follows impairment of this drainage
space, and lessened outflow through it. This blocking of the angle of
the anterior chamber must be regarded as an established fact in the
etiology of glaucoma. But because it is so definitely established, and
because so much work has been done with reference to it, we may attach
to it an undue importance.

The escape of the outflow of fluid from the eye is ultimately through
the veins. The general venous blood pressure is so low (often negative
in the great veins of the neck during inspiration) that no obstacle can
come from it to the ocular outflow. The venous blood pressure permits
the eyeball to become perfectly soft. We have all seen tension of 5 mm.,
or even less; and general venous pressure does not rise to the normal
intra-ocular tension. Increased intra-ocular pressure requires that
there must be some obst