s then the over plus amount. This over
plus amount may be in association with a rise of intra-ocular pressure,
and must be eliminated if the latter is to be controlled by a
non-operative procedure, or, indeed, by an operative one.

It is no easy matter to determine the presence of increased venous
pressure, although there are tolerably accurate instrumental technics,
and yet, as Henderson points out, it is just this increased general
venous pressure which is often detrimental. Therefore the perfunctory
use of such drugs as nitrite of amyl and the other nitrites may not be
in the least indicated when, for example, the venous pressure depends
upon inability of the right heart to perform its functions, and the drug
needed may, for example, be digitalis. Far better than pressure-reducing
drugs like nitrite of amyl, urgently indicated in some instances and for
some purposes, is the regulation of life and the restoration to their
normality of the metabolic processes, the elimination of the worry
which is usually the exciting agent that brings about the over plus
pressure, which may have as one of its expressions an acute rise of
intra-ocular tension. I believe that in the management of a case of
glaucoma, whether it be chronic or chronic with sub-acute exacerbations,
the greatest care with the aid of an expert clinician must be exercised
to find out exactly what mean pressure of the arterial and venous system
best conforms with the patient's general welfare, and I am bitterly
opposed, and I think with right, to the sudden reduction of tensions,
except in emergencies, without a perfect understanding of the facts I
have ventured to indicate. This does not for a moment mean that prior,
for example, to operative work it is not necessary to get rid by means
of drugs of an over plus tension, for surely the elimination of such an
over plus tension may be the means of preventing, for example, an
intra-ocular hemorrhage, and in this emergency we must not lose sight
of Gilbert's recent investigation, who has found that blood withdrawn to
the extent of 8 grams to each kilogram of the body weight always
produces lowering of the intra-ocular tension, appearing in six to eight
hours and lasting to the next day in simple glaucoma, and in
inflammatory glaucoma commencing the day after the venesection and
lasting two to three days. It is not necessary for me to point out the
value of free purgation and diaphoresis in this respect.

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