a of the comparative value of the
three methods that comprise the great majority of interventions made use
of by ophthalmic surgeons at the present time. I refer to _iridectomy_,
the _Lagrange operation_, and the _Elliot operation_. So far as regards
the last named procedure, I congratulate this Society that it has had an
opportunity of seeing a demonstration and hearing a discussion by the
famous ophthalmic surgeon who perfected it.

As regards the others let me recommend to you the complete description
of them given by Posey in _A System of Ophthalmic Operations_.

Let us consider the first of the three procedures just
mentioned--_iridectomy_--introduced by von Graefe. The mechanism of its
mode of cure is best studied in cases of acute primary glaucoma, when
there is apposition of the periphery of the iris to the cornea. In these
acute cases there is probably only a mere _apposition_, and the blocking
up of the sclero-iridian angle is largely mechanical. Here the root of
the iris is readily removed in its entirety and a really peripheral
iridectomy is easily done. When, however, a true _adhesion_ between
corneal and iridic tissue takes place the filtration angle is not so
easily opened. True peripheral adhesions are not readily broken up or
separated, and the iridectomy is, for that reason at least, not
effective. Moreover, this form of anterior synechia (resulting from a
true union of iris and cornea) is so intimate that the iris root is, by
the iridectomy, torn away only at the sclero-iridian angle at the
anterior border of the adhesion--and does not open up a channel into
Schlemm's canal. It is not, therefore, difficult to understand why
iridectomy alone in any of the forms of chronic glaucoma fails to open
up the true filtration spaces and does not provide a drain that permits
of an escape of fluid from the posterior chamber through the loose
tissue that surrounds it into the canal of Schlemm. Treacher Collins
found, after a careful examination of eyes upon which iridectomy had
been performed for glaucoma, that it is extremely rare for the initial
section to pass through the pectinate ligament, while Schlemm's canal
invariably escapes. Moreover, since the sclero-corneal incision is
uniformly oblique, the position and extent of the external wound does
not always furnish evidence of the character of the internal wound. In
all likelihood many cases of relief or cure following iridectomy are
those due to the formatio