Part 36 (1/2)

CHAPTER IV

OPERATIONS UPON THE SCLEROTIC

ANTERIOR SCLEROTOMY

=Indications.= Sclerotomy is an operation undertaken for the relief of increased intra-ocular tension. It is performed--

(i) Usually as a secondary operation when iridectomy has failed.

(ii) As a primary operation for the division of anterior synechiae causing tension.

A few surgeons prefer the operation to iridectomy, especially in cases of bup[h]thalmos. When practised after an iridectomy which has been done upwards, the sclerotomy is sometimes performed in a downward direction; otherwise the section is usually made upwards. The intra-ocular tension is probably relieved by the formation of a filtration cicatrix, and it is therefore probable that it may be largely superseded by the operations of cyclo-dialysis and sclerectomy.

When performed for the division of anterior synechiae the position of the incision should be planned according to the situation of the synechia to be divided.

=Instruments.= Speculum, fixation forceps, Graefe's knife with a narrow blade.

=Operation.= The operation is done under cocaine. Eserine should have been previously instilled in order to contract the pupil and prevent prolapse of the iris.

Graefe's knife should be pa.s.sed across the anterior chamber in the same manner and position as for a glaucoma iridectomy (see p. 221). In the _complete_ method the knife is made to cut out through the sclerotic, leaving a band of conjunctiva to hold the flap in position. In the _incomplete_ method a band of sclerotic is left in the periphery. If the operation is done in a downward direction, it is better for the surgeon to stand on the opposite side of the patient to the eye on which the operation is to be performed, operating across the patient.

=Complications.= Any of the complications which follow an iridectomy for glaucoma may occur (see p. 222). Prolapse of the iris is probably the most frequent.

CYCLO-DIALYSIS

=Indications.= This operation has only recently come into general use in this country, so that statistical results have at present by no means been worked out, but most satisfactory results have been obtained from it in individual cases; according to German authorities about 30 per cent. are permanently cured. Although at present its performance is largely limited to blind eyes and to eyes that have undergone previous operations for glaucoma, it is probable that it may come into further use as a primary operation in the treatment of chronic glaucoma and bup[h]thalmos. It is also of service in cases of dislocation of the lens backwards, a.s.sociated with increased tension, where iridectomy would certainly be followed by loss of the vitreous.

[Ill.u.s.tration: FIG. 119. CYCLO-DIALYSIS OPERATION. Showing the method of commencing the incision in the sclerotic; it is subsequently deepened with the point of the knife. The dotted lines mark the incision for turning forward the conjunctival flap.]

The operation has for its object the separation of the ligamentum pectinatum from its attachment to the sclerotic, with the probable result that the ciliary body and iris root become retracted by the ciliary muscle, so that the ca.n.a.l of Schlemm is opened up and again communicates with the anterior chamber. It also opens up a free communication between the anterior chamber and the suprachoroidal lymph-s.p.a.ces. The reduction of tension is often not fully manifest for about ten days after the operation.

=Instruments.= Speculum, fixation forceps, Graefe's knife, fine pair of straight iris forceps, fine pair of sharp-pointed straight scissors, iris spatula.

=Operation.= The operation is best performed under a general anaesthetic, as it is attended with considerable pain, although cocaine and adrenalin are frequently used and are always advisable, since the haemorrhage from the scleral vessels renders it difficult to gauge the depth of the wound in the sclerotic.

[Ill.u.s.tration: FIG. 120. CYCLO-DIALYSIS OPERATION. Showing the spatula separating the ciliary body and ligamentum pectinatum from the sclerotic.]

_First step._ By means of the straight iris forceps and sharp-pointed scissors a semilunar conjunctival flap is first raised over the site for the scleral incision. The incision in the sclerotic should be situated about 5 mm. behind the corneo-sclerotic junction over the ciliary region, the outer and upper quadrant of the eye being the easiest position for subsequent manipulation (Fig. 119).

_Second step._ With a Graefe's knife the fibres of the sclerotic are carefully divided in an oblique direction forward until the suprachoroidal lymph-s.p.a.ce is opened for about 3 mm. The first part of the incision is performed with the blade and completed with the point of the knife, the anterior flap of sclerotic being held forward by straight iris forceps. Heine uses a keratome, dividing the fibres of the sclerotic with the point by stroking it along the line of the incision.

The depth of the incision should be carefully gauged from time to time with the iris spatula; the pigment of the ciliary body is usually seen in the bottom of the wound when the sclerotic has been penetrated.

_Third step._ The iris spatula is directed forwards and inserted between the sclerotic and the ciliary body, keeping close to the former. With a gentle side-to-side movement the spatula is made to separate the ciliary body from the sclerotic for about one-eighth of its whole circ.u.mference; then the ligamentum pectinatum is detached from the sclerotic for about the same distance by gently pa.s.sing the spatula forwards and making the latter appear in the anterior chamber (Fig. 120). If it be desired to evacuate the anterior chamber, the spatula is slightly rotated so as to allow the escape of the aqueous. As a rule this is not necessary or even advisable. The spatula is then withdrawn and the conjunctival flap is replaced in position. Eserine should be instilled.

=Complications.= (1) Unless the incision be carried carefully through the sclerotic, or the manipulations with the iris spatula be very gentle, loss of vitreous is liable to take place. As a rule, this, if not great, is of little consequence. (2) In pa.s.sing the iris spatula forward to separate the ligamentum pectinatum the point may pa.s.s between the layers of the cornea; this is recognized in the resistance offered to the side-to-side movement of the spatula, which should be withdrawn slightly and the point depressed so as to engage the ligamentum pectinatum. (3) Subchoroidal haemorrhage has been known to occur after the operation.

SCLERECTOMY