brought about
by lowering general vascular pressure._ Much has been written in regard
to the association between increased vascular pressure and increased
intra-ocular pressure. It is not my province to analyze observations
often contradictory and not infrequently inaccurate. This much seems to
be established: First, that at corresponding ages there is usually a
higher average blood pressure in glaucomatous subjects than there is in
non-glaucomatous subjects; second, that arteriosclerosis and therefore
usually increased blood pressure, with all its concomitant conditions,
is correctly classified as an exciting cause of glaucoma; and third,
that the regulation of this increased blood pressure is part of the
advantageous management of increased intra-ocular pressure, although it
may be too much to say, as Gilbert has, that blood pressure and
intra-ocular pressure rise and fall together. It may be true, as Thomas
Henderson says, that the intra-ocular pressure is influenced by changes
in the general arterial or general venous pressures, whereby a rise in
general arterial pressure induces a proportionate rise in the
intra-ocular pressure, but it would seem that future investigations must
confirm this statement before it can be entirely accepted, as well as
his further statement that the effect of an increased general venous
pressure is a direct one, producing millimeter for millimeter a
corresponding increase in the intra-ocular pressure.

Now, it goes without saying, if these data are correct, or even only
partly correct, that part of the treatment of the increased intra-ocular
pressure state must be constitutional in that the vascular pressures
should be lowered in order that the beneficial effect of their
relationship to the intra-ocular pressure shall be established. It is
further a great mistake to drive down a high arterial pressure simply
because that exists. In other words, it is often necessary from the
general standpoint that a certain amount of plus pressure shall remain
if the patient's general well-being is to be maintained. There must
always be a differential diagnosis between plus pressure and what may be
called over plus pressure. That is to say, a man may be perfectly
comfortable and properly need, for example, a pressure of 160 or 165
mm., which is above the physiologic limit, but which is a plus pressure,
while some disturbance in his general life may add to that 10, 15 or 20
mm. more of pressure, which i