prevents prolapse of the iris.

Under no circumstances must iris be left between the lips of the wound.

Although Lagrange advocated iridectomy in all cases in his first
communication, he no longer judges the procedure to be necessary in all
instances, reserving it for cases in which for any reason, such as
hypertension, prolapse is to be feared.

While Lagrange holds that it is necessary to open the anterior chamber,
Bettremieux thinks that a removal of but a portion of the thickness of
the sclera suffices. His procedure is as follows: After raising a flap
of conjunctiva from the neighborhood of the limbus a medium sized
needle, curved and flattened towards its point and firmly grasped in a
needle holder, is thrust superficially into the sclera tangentially to
the upper edge of the cornea, so as to become fixed in the capsule of
the eyeball. A small shaving of the sclera, about 1/2 mm. thick, 11/2 to 2
mm. broad and from 2 to 3 mm. long, is then excised by means of a narrow
Graefe knife. The scleral slip is then freed from the conjunctiva at
each end and the mucous membrane brought together over the wound by fine
catgut sutures.

As you are well aware, numerous operators regard the Lagrange operation
as superior to the iridectomy of von Graefe because they believe there
is filtration through the newly formed tissue between the lips of the
operative wound. Among those of many observers the conclusions of
Ballantyne may be quoted: "The results of sclerectomy vary according to
the degree of hypertension of the eye operated on. Three varieties of
cicatrix are distinguishable according to the amount of sclera excised:
(1) that in which there is mere thinning of the sclera owing to the
excised portion not reaching the posterior surface of the cornea
(conjunctiva smoothly covers the cicatrix); (2) that represented by a
subconjunctival fistulette, due to excision of the whole thickness of
the sclera, in an eye with moderate tension (the conjunctiva lies
smoothly over the cicatrix); (3) the fistulous cicatrix with an
ampulliform elevation of the overlying conjunctiva, resulting from
excision of the whole thickness of the sclera in an eye the seat of high
tension. In cases of high tension, even a simple sclerectomy will allow
ample filtration, owing to the gaping of the wound, while in cases
without elevation of the tension, sclerectomy will be quite ineffectual.
Lagrange therefore proposes the following rules of procedure: (