We will now return to the consideration of the second school in which
scissors were introduced through a previously made corneal section and
a free incision was made in the iris-membrane, or a portion of the
membrane excised.
[Illustration: Fig. 17.--Wenzel’s cataract knife, and method of
incision (after Mackenzie).]
Janin,[10] in 1768, having abandoned the procedure of Cheselden,
proposed a new method. He incised the cornea below as for cataract
extraction, and raised the corneal lip with a spatula while he
introduced a pair of curved scissors, the lower blade of which was
pointed. He plunged this sharp blade through the iris-membrane,
and with a single vertical cut made a crescentic pupil which gaped
sufficiently for visual purposes. As this is the first known
description of iridotomy by the scissors method it is probable that
Janin was the originator of this procedure.
Wenzel,[23] in 1786, employed a different method. With a lance-shaped
cataract knife he entered the cornea, dipped through the
iris-membrane, returned to the anterior chamber, and continuing to cut
made a counter-puncture on the opposite side of the cornea, following
which he completed his cataract incision. This gave a semilunar flap of
iris tissue which could easily be excised by scissors passed through
the large corneal opening (Fig. 17).
[23] Wenzel, Baron de: Traité de la Cataracte, Paris, 1786, translated
by James Ware, London, 1805, ii, p. 256.
[Illustration: Fig. 18.--Maunoir’s scissors.]
[Illustration: Fig. 19.--V-shaped iridotomy with scissors (Maunoir).]
[Illustration: Fig. 20.--Parallelogram pupil (Maunoir).]
Maunoir,[24] in 1802, took up the method of Janin, with the object of
improving it. He made an incision near the corneal margin, through
which he introduced a pair of long, thin, angular scissors of his own
design (Fig. 18), one blade of which was sharp-pointed like a lancet,
and the other button-pointed like a probe. The iris-membrane was
then punctured by the sharp blade at about the natural location of
the pupil, and an incision executed toward the ciliary margin of the
iris. Finding that this single incision did not always succeed,[25] he
subsequently improved this method by making a second incision from the
pupillary area toward the iris margin, in the line of the radiating
iris fibers, thus making a divergent V (Fig. 19). This triangular flap
was then allowed to shrink back, or if too stiff, was drawn out and
excised. The resultant pupil assumed the shape either of a triangle, a
parallelogram (Fig. 20), or a crescent (Fig. 21). He always made his
incision parallel with the radiating fibers of the iris and across the
circular fibers.
[24] Maunoir, Jean Pierre: Mémoires sur l’Organisation de l’Iris, et
l’Opération de la Pupille Artificielle, Paris, 1812.
[25] Medico-Chir. Trans., London, 1816, vii, p. 301, and ix, p. 382.
Scarpa,[15] in 1818, having abandoned his own method of
iridodialysis as wholly unsatisfactory, adopted Maunoir’s
procedure with enthusiasm, chiefly because he had by a friendly
correspondence[24] personally encouraged Maunoir with advice and
suggestion during its development. He indorsed Maunoir’s plan of a
double incision when he stated his conviction that “experience has
proved that in order to obtain, with the most absolute certainty, a
_permanent_ artificial pupil, it is necessary to make _two_ incisions
in the iris so as to form a triangular flap in the membrane, in the
form of a letter V, the apex being precisely in the center of the iris
and the base near the great margin.” Some have claimed that Scarpa
himself originated the V-shaped incision, but he gives Maunoir full
credit for its successful accomplishment, although he does suggest some
additional indications for its practical application.
[Illustration: Fig. 21.--Crescent pupil (Maunoir).]
His opposition to the knife-needle incision of Cheselden arose from
the fact that the pupil either did not open, or if it did open would
not remain permanent, chiefly because of the single iris incision. His
antagonism to the more successful procedure of Adams was the result
of a caustic personal controversy[16] with that skilful surgeon,
who ably parried his charges.[14] His great influence with the
profession of that day, however, served to check the sentiment in favor
of Adams’ procedure, and when the weight of his indorsement was cast in
favor of Maunoir’s operation the scales were decisively turned toward
the side of the scissors method.
Mackenzie,[26] in 1840, practiced Maunoir’s operation with considerable
success, but in certain cases found it necessary to employ a slight
modification of this procedure. He reversed Maunoir’s incision by
making the same divergent V across the radiating fibers of the iris
instead of parallel with them (Fig. 22), thus securing a triangular
pupil (Fig. 23), which Lawrence[27] thought might succeed in some cases
where Maunoir’s method would not be available.
[26] Mackenzie, William: Diseases of the Eye, 3rd. ed., London, 1840,
p. 746, American edition, edited by Hewson, Philadelphia, 1855, p. 815.
[27] Lawrence, Sir William: Diseases of the Eye, American edition,
edited by Hays, Philadelphia, 1854, p. 478.
[Illustration: Fig. 22.--Mackenzie’s incision in cornea and
iris-membrane (Mackenzie).]
[Illustration: Fig. 23.--Resulting triangular pupil from Mackenzie’s
incision (Mackenzie).]
Bowman,[28] in 1872, proposed a method which, though surgically
difficult to execute, was quite ingenious, and may have been the
initial suggestion that stimulated DeWecker to write his monograph
in the following year. I will quote his description as follows: “We
make a double opening simultaneously on opposite sides of the cornea.
It is more convenient, of course, to make these two openings in a
horizontal than in a vertical direction. I then run a pair of scissors
in two diverging lines (V) from each incision, thus enclosing between
the incisions a large square or rhomboidal portion of the iridial
region including the pupil, and all the structures there. You then
withdraw the portion thus cut out. There is no drag on the ciliary
region; whatever is withdrawn has been cut away from its connections
beforehand” (Figs. 24, 25 and 26).
[28] Transactions, Fourth Int. Ophth. Cong., London, 1872, p. 179.
[Illustration: Fig 24.--Plan of Bowman’s first iris incision.
Divergent V.]
[Illustration: Fig. 25.--First incision completed. Plan of second,
showing double V.]
[Illustration: Fig. 26.--Rhomboidal pupil, resulting from Bowman’s
iridotomy.]
This method is simply an elaboration of the one proposed by Maunoir, in
which, instead of forming one divergent V, Bowman has made a duplicate
incision on the opposite side, and by joining the bases of these two
resultant triangles has caused them to take the shape of a rhomboid,
thus <>.
[Illustration: Fig. 27.--Stop keratomes, straight and angular
(De Wecker).]
[Illustration: Fig. 28.--Forceps-scissors (pinces-ciseaux) (DeWecker).]
DeWecker,[29] in 1873, published his admirable monograph on iridotomy,
in which he proposed the operation which bears his name, and which
has long stood as the best recognized method of this procedure. He
advocated two different ways of performing this: 1, simple iridotomy,
and 2, double iridotomy.
[29] De Wecker, Louis: Annales d’Oculistique, Sept., 1873, p. 123, et
seq.
1. _Simple Iridotomy._--This is practically the same operation as
Critchett’s sphincterotomy and Bowman’s visual iridotomy, although
differently executed. It has been supplanted in our day by iridectomy,
and does not, therefore, come within the purview of this discussion.
2. _Double Iridotomy._--He rightly claimed that this was both
antiphlogistic and optical in its purpose. He employed two distinct
methods, which he designated as (_a_) iritoectomie, and (_b_)
iridodialysis. The instruments he used were a small stop-keratome (Fig.
27) and a pair of specially devised fine iris scissors (pinces-ciseaux)
(Fig. 28), one blade being sharp pointed and the other blunt. These
scissors were a great mechanical advance over all previous instruments
of this kind, and undoubtedly proved to be a most important element in
the success of his procedure.
[Illustration: Fig. 29.--Iritoectomie. Convergent V (DeWecker).]
[Illustration: Fig. 30.--Iridodialysis. Divergent V (DeWecker).]
(_a_) _Iritoectomie._--He entered the stop-keratome through the cornea,
made an exact 4 millimeter incision, and then partly withdrew it
while letting the aqueous slowly escape. As soon as the iris-membrane
floated up against the knife, he pressed forward, making a 2 millimeter
incision in the iris. Slowly withdrawing the knife, he introduced
the sharp point of the scissors through the iris buttonhole and cut
obliquely from either extremity of the incision toward the apex of a
triangle, thus making a convergent V (Fig. 29). He then grasped the
resulting triangular flap with the forceps and removed it, leaving an
open central pupil.
(_b_) _Iridodialysis._--His second method was a counterpart of
Maunoir’s earlier operation, with the addition of iridodialysis. He
made the corneal and iris incision with the stop-knife, as in the
previous method. Slipping in his scissors he cut from the center of the
iris-membrane toward the periphery, and duplicated this incision at an
oblique angle to the first, thus making a divergent V (Fig. 30). This
formed a triangular flap which he grasped with forceps and tore from
its ciliary attachment by iridodialysis.
DeWecker’s procedure was planned by a skilled operator, and required
great dexterity in its execution. When successful, however, the result
was most brilliant. Nevertheless, it was impossible to eliminate the
danger of hemorrhage and loss of fluid vitreous in iritoectomie, while
in iridodialysis there was the added danger of a torn ciliary surface
and traction on the ciliary body. His strict injunction to have a
trained assistant hold up the speculum blades in order to avoid the
loss of fluid vitreous, showed how much he feared this disastrous
contretemps. The success of his method of incision is well shown in the
illustration of his two cases (Figs. 31 and 32).
[Illustration: Fig. 31.--Pupil by iritoectomie. Two incisions.
Convergent V (DeWecker).]
[Illustration: Fig. 32.--Stenopaic pupil. Single iris incision
(DeWecker).]
I have already suggested the possibility of Bowman’s paper before the
London Congress of 1872 having given origin to DeWecker’s monograph
in 1873. This seems quite reasonable when we consider that Bowman
proposed two methods of iridotomy, one his double V operation with a
rhomboidal pupil (previously quoted), and the other a visual iridotomy
or sphincterotomy, by cutting through the pupillary margin with a blunt
corneal knife. These two methods are exact prototypes of DeWecker’s
proposals. Furthermore, DeWecker was present at the London Congress
where he heard Bowman’s paper, and took part in its discussion. In
fact, thirteen years later DeWecker acknowledged[30] that after
considering the objections to Bowman’s method of iridotomy “I addressed
myself at that time to the search for an instrument which allows
the avoidance of all traction on the iris, and which can be handled
through a narrow opening, while exerting its cutting action in a plane
parallel to the surface of the cornea, against which the diaphragm of
the iris applies itself, after the escape of the aqueous humor. The
forceps-scissors having been discovered, it was easy for me to cause to
be revived the procedure of Janin, and to make it decisively take rank
in modern ocular surgery.”
[30] DeWecker et Landolt: Traité Complet d’Ophtalmologie, Paris, 1886,
ii, p. 393.
DeWecker makes only a casual reference to Maunoir’s method, but credits
Janin with the original suggestion of the method which he has thus
elaborated. Nevertheless, it is quite evident that DeWecker’s method
was simply a modification of the one outlined by Maunoir seventy
years before. Furthermore, he lays down the same rule that Maunoir
first offered: “Always cut parallel to the radiating fibers and
perpendicularly to the circular fibers of the iris.”