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is probably relieved by the formation of a filtration cicatrix, and it is therefore probable that it may be largely superseded by the operations of cyclo-dialysis and sclerectomy.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

The object of the operation is the production of a filtration cicatrix free from iris tissue for the relief of intra-ocular tension in chronic glaucoma.

=Instruments.= As for glaucoma iridectomy, with the addition of a small curved pair of scissors.

=Operation.= Under cocaine.

_First step._ The incision is performed as for glaucoma iridectomy (see p. 221), except that the incision should be rather smaller and should be carried more obliquely through the sclerotic, so that a long scleral flap is obtained. A large conjunctival flap is very essential to cover the wound.

_Second step._ An iridectomy is usually performed as for glaucoma; this may be omitted.

_Third step._ After all the bleeding has ceased, the conjunctival flap is turned forwards on to the cornea so as to expose the scleral flap; with small curved scissors made for the purpose, an elliptical portion is removed from the sclerotic by a single snip (Figs. 121 and 122), and the conjunctival flap is replaced in position. As a result, a hole is made into the anterior chamber, which thus communicates with the subconjunctival tissue, which is bulged forwards in the form of a clear vesicle by the escaping aqueous when the wound has healed.

[Ill.u.s.tration: FIG. 121. LAGRANGE OPERATION FOR THE PRODUCTION OF A CYSTOID SCAR IN CHRONIC GLAUCOMA. Showing the method of removing a piece of the sclerotic.]

[Ill.u.s.tration: FIG. 122. LAGRANGE OPERATION FOR CHRONIC GLAUCOMA.

Showing the piece of sclerotic removed by the scissors (black lines).]

The immediate results of this operation are satisfactory provided that enough sclerotic be removed to produce a filtration cicatrix. As yet sufficient time has not elapsed for any statistical results to be obtained, but the cases in which the operation has been performed are reported as satisfactory.

POSTERIOR SCLEROTOMY

=Indications.= Posterior scleral puncture is performed--

(i) For the relief of tension, the indications for which have already been described under the indications for iridectomy in glaucoma (see p.

218).

(ii) For the evacuation of fluid behind a detached retina.

The operation in the latter instance, although not yielding very satisfactory results with regard to the reattachment of the retina, may be carried out with some hope of success in certain cases. Before performing the operation the pathological cause of the detachment should be carefully investigated, for it is obvious that it would be useless to perform the operation in a case of detachment due to a choroidal tumour or if definite bands of fibrous tissue could be seen in the vitreous pulling off the retina. Undoubtedly it should be undertaken as soon as possible after the detachment has occurred and the puncture should enter the s.p.a.ce filled with subretinal fluid. Whether the puncture should penetrate the overlying retina is still a disputed point.

After the operation a pressure bandage should be applied and the patient should be kept on his back and not allowed to raise his head from the pillow for at least three weeks. This latter part of the treatment is most essential; indeed as good results may be obtained with complete rest as by performing scleral puncture. Unfortunately, recurrence is very liable to take place whichever method be used, even if reattachment of the retina be obtained.

=Instruments.= Speculum, fixation forceps, Graefe's knife.

=Operation.= Under cocaine. If no special position be indicated the puncture is best made upwards and inwards. The patient is made to look outwards and downwards. The conjunctiva over the sclerotic, well behind the ciliary body, is drawn down so that when released it shall form a valvular opening to the scleral wound. The Graefe's knife is driven through the conjunctiva and sclerotic, the incision being made antero-posteriorly in the direction of the fibres of the sclerotic to avoid wounding the choroidal vessels. It is probably better to enlarge the wound when withdrawing the knife than to turn the latter at right angles before it is withdrawn, as has been recommended by some surgeons.

A bead of vitreous usually escapes under the conjunctiva. If the tension be not lowered, gentle ma.s.sage of the globe through the lid should be employed.

PARACENTESIS OF THE ANTERIOR CHAMBER

=Indications.= Evacuation of the contents of the anterior chamber is performed for several conditions:--

(i) To reduce the tension of the eye when due to an altered consistency of the aqueous, as for instance in cyc.l.i.tis.