CHAPTER III

OPERATIONS UPON THE IRIS

IRIDOTOMY

=Indications.= Iridotomy is an operation which is performed when the iris has become drawn up after a cataract extraction, so that there is no pupil, or the pupillary area is covered by the upper lid. A long interval should elapse between the extraction and the iridotomy, since these cases have usually suffered from cyclitis following the operation. Iridotomy should not be performed for at least six months after all signs of cyclitis have disappeared, for the frequent failure of the operation is due to the fact that the opening made in the iris and underlying capsule becomes filled with fibrous exudation as the result of cyclitis, which is frequently set up again by the operation if undertaken before a sufficient time has elapsed for the eye to settle down after the inflammation. The ideal operation, therefore, is to make an artificial pupil with the least amount of trauma to the ciliary body.

=Instruments.= Speculum; fixation forceps; a long, narrow, bent ‘broad needle’; Tyrrell’s hook, iris scissors, iris forceps, and spatula.

=Operation.= Many operations have been devised for this most troublesome condition, but the following is the one that the author has found to be successful.

The operation is usually performed under a general anæsthetic, but this is not essential.

_First step._ The surgeon stands facing the patient on the same side as the eye to be operated on. The long, bent, broad cutting needle is passed into the anterior chamber from the limbus downwards and inwards, and is driven directly through the iris and underlying capsule. The needle is then made to pass in an upward and outward direction behind the iris into the pupillary area above, or if no pupil be present, again through the iris (Fig. 102). The bent broad needle is made to cut laterally by slightly deflecting the handle so as to produce a band of iris and capsule; the cutting needle is then withdrawn.

_Second step._ A Tyrrell’s hook, bent to the correct angle, is passed beneath the band (Fig. 103), which is drawn into the wound and removed with iris scissors. A large opening is thus obtained with a minimum amount of trauma. If the hook should slip, the band may be seized with iris forceps, withdrawn from the wound, and removed.

=Alternative methods.= The following methods have been practised:--

=Simple incision= across the fibres of the iris by means of Graefe’s or Knapp’s knife.

=Division with scissors= through a wound of the limbus.

By these two methods the opening produced is small, and is very liable to be closed by the subsequent cyclitis. The following operation yields more satisfactory results.

=Kuhnt’s operation.=

=Instruments.= Speculum, fixation forceps, Graefe’s knife, iris forceps and scissors.

_First step._ The surgeon, standing facing the patient, enters the anterior chamber about 2 millimetres inwards from the limbus at the junction of the middle and lower third of the cornea with a Graefe’s knife, the cutting edge directed downwards. The knife is then made to penetrate the iris and underlying capsule, and to travel beneath this to a similar point on the other side, where it is made to come back again into the anterior chamber by again penetrating the iris, and finally out again through the cornea. The knife is then made to cut out in a downward direction.

_Second step._ Iris forceps are inserted and the flap of iris and capsule is withdrawn and as much of it removed as possible. A more or less triangular opening usually results.

=Ziegler’s operation.=

=Instruments.= Ziegler’s knife needle, speculum, fixation forceps.

The object of the operation is to cut a V-shaped flap in the iris and underlying capsule, folding the flap backwards on its base so as to form a triangular opening in the iris membrane to serve as a pupil.

_First step._ The knife needle is entered at the corneo-sclerotic junction with the blade turned on the flat and is passed completely across the anterior chamber to within 3 mm. of the apparent iris periphery. The knife is then turned edge downwards, and carried 3 mm. to the left of the vertical plane (Fig. 104).

_Second step._ The point is now allowed to rest on the iris membrane, and with a dart-like thrust the membrane is pierced. Then the knife is drawn gently up and down with a saw-like motion, without making much pressure on the tissue to be cut, until the incision has been carried through the iris tissue from the puncture in the membrane to just beneath the corneal puncture. This movement is made wholly in a line with the long axis of the knife, the shank passing to and fro through the corneal puncture, loss of the aqueous being avoided in the manipulation (Fig. 105).

_Third step._ The pressure of the vitreous will now cause the edges of the incision to bulge open immediately into a long oval. The knife-blade is raised until it is above the iris membrane, and is then swung across the anterior chamber to a corresponding point on the right of the vertical plane. Owing to the disturbance in the relation of the parts made by the first cut, this point is somewhat displaced and the second puncture must be made 1 mm. further over.

_Fourth step._ With the knife-point again resting on the membrane, a second puncture is made and the incision is carried rapidly forward by the sawing movement to meet the extremity of the first incision at the apex of the triangle, thus making a V-shaped cut. Care must be taken that the pressure of the knife-edge on the tissue shall be most gentle, and that the second incision shall terminate a trifle inside the extremity of the first, in order that the last fibres may be severed and thus allow the apex of the flap to fall down behind the lower part of the iris membrane (Fig. 106). When the operation has been completed the knife is turned on the flat and withdrawn.

IRIDECTOMY

The operation of iridectomy differs widely in its performance, according to the different conditions for which it is used. Hence it is better to prefix the condition for which it is employed, thus: preliminary iridectomy, optical iridectomy, glaucoma iridectomy.

Apart from being one of the stages of removal of a cataract, already described, it is performed as an independent operation in the following conditions:--

1. For optical purposes (optical iridectomy).

2. For the relief of glaucoma, primary and secondary (glaucoma iridectomy).

3. For small growths at the free margin of the iris.

4. For prolapse of the iris through a wound.

OPTICAL IRIDECTOMY

=Indications.= Iridectomy for optical purposes is performed for a centrally situated nebula of the cornea and in some very rare cases of small central opacities in the lens. In the latter condition it is rarely of much value, as nearly all the rays which enter the eye pass through the central portion of the lens. Further, in this condition the lens may be removed and better sight obtained with glasses. Optical iridectomy should always be performed opposite a clear portion of the cornea, the lower segment of the eye being chosen, otherwise the coloboma may be subsequently covered by the upper lid. The site of election for the operation is downwards and inwards, but in all cases the patient should be carefully examined in the following ways: (1) the vision is tested, any refraction being corrected without a mydriatic; (2) the pupil is then dilated, and the best situation for the iridectomy determined by means of a stenopaic slit. The vision must be definitely improved by the use of these before operation can be advised. The disadvantage of an iridectomy is that it allows more light to enter the eye, and, if the periphery of the lens be uncovered, spherical aberration may result. For both these reasons, therefore, it is advisable to make the iridectomy as small as possible. Tattooing of the central scar in the cornea will often diminish the amount of light entering the eye, but before undertaking the latter operation, the eye should be cocainized and the area covered with a piece of black paper to see if the vision is improved thereby.

=Instruments.= Speculum, fixation forceps, bent broad needle or small keratome, Tyrrell’s hook, iris forceps, scissors, and spatula.

=Operation.= The operation is usually performed under cocaine.

_First step._ The eye is fixed by grasping the conjunctiva directly opposite the spot at which the incision is to be made. The incision is then made by means of a keratome or bent broad needle directly behind the limbus, and enlarged laterally if desired (Fig. 107).

_Second step._ A Tyrrell’s hook, bent at the correct angle, is passed on the flat into the anterior chamber. When the margin of the iris is reached the handle is rotated and the hook is made to engage the free border of the iris, which is then withdrawn from the wound; a small portion is removed with scissors, which should be held at right angles to the wound when dividing the iris (Fig. 108).

_Third step._ The iris should be carefully replaced and the pupil kept under the influence of eserine until the anterior chamber has re-formed, when atropine should be substituted.

Care must be taken to see that the Tyrrell’s hook presents no sharp angle, and great care is required in its manipulation, otherwise the lens capsule may be damaged, and traumatic cataract will result. If the iris slips from the grasp of the Tyrrell’s hook, iris forceps should be used, the iris being grasped near its free margin and as small a portion as possible withdrawn.

=Brudenell Carter’s method.= The ordinary optical iridectomy divides the sphincter iridis and so inhibits the activity of the pupil. With the idea of obviating this, Brudenell Carter removed a small portion of the iris (button-hole), leaving the pupillary margin intact. On the whole the results of the latter operation are no more satisfactory, and the operation is more dangerous to perform owing to the likelihood of wounding the lens, and to the fact that monocular diplopia occasionally results.

The pupil should be under the influence of eserine. The incision is made as in the previous operation. De Wecker’s iris scissors are inserted open into the anterior chamber, closed, and the piece of iris which bulges up between the blades cut off; this can usually be withdrawn with the scissors; or if not, it should be removed subsequently by forceps.

GLAUCOMA IRIDECTOMY

=Surgical and pathological anatomy.= The fluid in the anterior and posterior chambers of the eye is secreted from the ciliary body by a process of modified filtration. The fluid passes partly direct into the posterior chamber and partly behind the suspensory ligament of the lens, making its way forward into the posterior chamber through the fibres of the suspensory ligament. From the posterior chamber it passes into the anterior through the pupil; from the anterior it filters at the angle of the anterior chamber through the ligamentum pectinatum into the canal of Schlemm; thence it is carried into the blood-stream by the venous anastomosis in that region (Fig. 110).

The essential change found in all cases of primary glaucoma is the blocking of the angle of the anterior chamber owing to the root of the iris being applied to the back of the cornea, and thus preventing the filtration of the fluid into the canal of Schlemm, as a result of which the tension of the eye is raised, either acutely (acute glaucoma) or slowly from time to time (chronic glaucoma) (Fig. 111). The aim of every operation for the permanent relief of glaucoma is the opening up of Schlemm’s canal at the angle of the anterior chamber or the creation of a new lymph channel between the anterior chamber and the subconjunctival tissue (filtrating cicatrix). Although this latter condition is not unattended by the risk of the spread of inflammation from the conjunctiva to the interior of the globe, it is not an inadvisable condition to obtain in some cases of chronic glaucoma if the scar be small and free from iris tissue; in this disease the opening up of the canal of Schlemm by iridectomy is often impossible. (See Sclerectomy, p. 231.)

=Indications.= Since the days of von Graefe, who first performed iridectomy empirically for the relief of glaucoma, the operation has held the first place in its treatment.

(i) =In primary glaucoma.= Iridectomy should be undertaken as early as possible in the disease. _In acute cases_, unless the tension is relieved, the disease ends in rapid destruction of the sight. Operation should always be undertaken as quickly as possible, provided the patient has not lost his perception of light for longer than about ten days.

Whilst waiting for the operation, the pupil should be put under the influence of eserine (2 to 4 grains to the oz.) with the idea of reducing the tension by contraction of the pupil. Some surgeons, in addition to using eserine, perform a posterior scleral puncture with the idea of temporarily reducing the tension and allowing the acute symptoms to subside, and do the iridectomy some twenty-four to forty-eight hours later. This method is extremely useful (_a_) in cases where a general anæsthetic is inadvisable, since the reduction of tension allows cocaine to diffuse into the eye; (_b_) in cases liable to subsequent intra-ocular hæmorrhage, a more gradual reduction of tension being obtained, rupture of a choroidal vessel is less likely to occur; (_c_) a deeper anterior chamber is often obtained, and hence there is less risk of wounding the lens during the operation; (_d_) in cases where the operation has been performed in one eye and the lens has been subsequently extruded on the dressings.

_In chronic cases_ early iridectomy is desirable, since the root of the iris applied to the posterior surface of the cornea becomes atrophic, so that when an iridectomy is performed the iris tears off at the anterior part of the atrophic portion, leaving the angle of the chamber still occluded by its root (Figs. 112 and 113). It is especially in these cases that a filtrating cicatrix, which sometimes follows iridectomy or sclerotomy, is desirable, and indeed some surgeons (Herbert and Lagrange, see p. 231), have recently performed operations with this idea in view, and it is probable that this operation or cyclo-dialysis will prove to be of use in these cases.

Operation is only contra-indicated in a few very rare cases in which the tension is controlled by the use of eserine.

(ii) =In congenital glaucoma (bup[h]thalmos).= In this affection the results of iridectomy vary. Without doubt, the tension has been relieved by iridectomy in some cases, and either this operation, sclerectomy, or cyclo-dialysis should be tried if the disease be not too far advanced.

(iii) =In secondary glaucoma.= For obvious reasons the predisposing causes should always be taken into consideration. Thus it would be of no use to perform an iridectomy in the case of a growth in the choroid. On the other hand, an iridectomy would be unjustifiable for soft lens matter in the anterior chamber, which merely requires evacuation. An early iridectomy in cyclitis is not likely to influence the course of the disease favourably; at the most a paracentesis is required. As the early stages of cyclitis may give rise to tension, it is essential that every case of glaucoma should be examined for keratitis punctata before operation.

In iris bombé and total posterior synechiæ an iridectomy is indicated more to re-establish the communication between the anterior and posterior chambers than to clear the angle, and therefore it need not be so extensive. In cases of iris bombé where iritis is still present, and in cases of cysts of the iris, transfixion is all that is necessary.

It is very doubtful if iridectomy in glaucoma following thrombosis of the central vein is justifiable, for as a rule the tension is not permanently relieved thereby. In secondary glaucoma following cataract extraction or anterior synechiæ, division of the capsule or the anterior synechiæ will often relieve the tension.

=Instruments.= Speculum, fixation forceps, Graefe’s knife (with a short, stiff, narrow blade), iris forceps, scissors, and spatula.

=Operation.= With the idea of opening up the angle of the anterior chamber by removing the iris as near its root as possible, the incision should be made somewhat further back behind the corneo-sclerotic junction than in cataract extraction. At the same time, if the incision be placed too far back the ciliary body is liable to prolapse into the wound. The old idea of opening up the canal of Schlemm by dividing it has been abandoned, as to do so would certainly result in prolapse of the ciliary body; and even if this did not happen, no good would result, since the canal would become closed subsequently by cicatricial tissue.

Although von Graefe used a keratome for making the incision, most British surgeons of the present day use a Graefe’s knife, as it gives an incision that is less shelving and more irregular, thus predisposing to the formation of a filtrating scar; a good conjunctival flap is obtained with it and there is less risk of wounding the lens.

When performing the iridectomy it is practically impossible to cut the iris with scissors at its attachment to the ciliary body, and it is better to rely on tearing it off from the ciliary body, as it is in this situation that the iris is thinnest and most likely to give way, provided it has not become atrophic by prolonged contact with the cornea.

In acute cases and in cases of secondary glaucoma where there are many adhesions a general anæsthetic is desirable.

_First step. The incision._ The position of the surgeon is as for cataract extraction. The eye is fixed by grasping the conjunctiva close to the limbus downwards and inwards. If the patient be under an anæsthetic, two pairs of fixation forceps should be used, one being held by an assistant. Occasionally in glaucoma the conjunctiva tears very easily, and in these cases scleral forceps are of use, or, if the knife be already in the eye, grasping the insertion of the superior or inferior rectus. The Graefe’s knife should be directed downwards and inwards towards the point of fixation, the point being passed through the sclerotic 1.5 mm. behind the limbus to the outer side. Directly the anterior chamber is entered, the handle is depressed towards the patient’s chin. The knife-point is kept superficial to the iris and is passed very slowly across the anterior chamber, close to its periphery until the position of the counter-puncture is reached. The counter-puncture should be situated about 1 mm. behind the limbus in a direct line with the original puncture. Care must be taken in making the counter-puncture that the knife-point does not slip back on the sclerotic and so emerge further back in the eye than is desired. The knife is then made to cut out upwards and a good conjunctival flap is obtained. The incision should be carried out slowly, so that the aqueous escapes gradually, as sudden reduction in the intra-ocular tension is liable to lead to intra-ocular hæmorrhage.

_Second step. The iridectomy._ The iris forceps are inserted closed into the anterior chamber, opened, and made to grasp the iris near the periphery (Fig. 114) towards the side of the wound on which the iris is first to be divided; then with a slight side-to-side movement of the forceps the iris is withdrawn from the wound until its peripheral attachment to the ciliary body, near where it is held by the forceps, is felt or seen to give way (irido-dialysis) (Fig. 115). The iris is then drawn a little further out from the wound, and one side of the dialysis is divided with the scissors as near the scleral wound as possible. The iris held in the forceps is then pulled over to the other angle of the wound, and as much of it as possible is pulled out and divided close to the scleral incision (Fig. 116). The angles of the incision are freed from iris by means of the spatula and the conjunctival flap is replaced in position. Both eyes are then bandaged.

=After-treatment.= The patient should be kept in bed for a week, and during the first four days should not be allowed to raise the head from the pillow. After that time the eye not operated upon may be uncovered; eserine should have been instilled into it before the operation and at subsequent dressings to prevent the possible onset of glaucoma owing to the dilatation of the pupil which follows the application of the bandage to the eye. It is not necessary to use any mydriatic or myotic for the eye which has been operated upon.

=Complications.= These may be immediate or remote.

=Immediate.= 1. In passing a Graefe’s knife into the anterior chamber to make the section, care must be taken that the cutting edge is directed upwards. If by accident it should be inserted with the cutting edge directed downwards the knife should be withdrawn and the operation postponed for a day or two until the anterior chamber has re-formed.

Care must be taken that the cutting edge is kept on the same plane as the upper edge of the back of the knife, otherwise the incision is liable to pass further back than is intended.

2. _Splitting the cornea._ The anterior chamber often being little more than a potential space, the knife may be passed between the lamellæ of the cornea and may not enter the anterior chamber at all. The indication that the knife-point is not in the anterior chamber is that there is no diminished resistance, such as is usually felt when the knife enters the chamber; if its point be slightly depressed, the cornea will be seen to dimple in over the position of it, showing that the point is not free in the anterior chamber.

3. _Locking of the knife._ This is due to the fact that the puncture and counter-puncture are not made in the same plane, the knife being twisted. It is much more liable to occur if a knife be chosen with a blade which is not sufficiently stiff. As a rule the blade can be made to cut out, but failing this, the knife should be withdrawn sufficiently to allow a fresh counter-puncture to be made, or else withdrawn altogether and the operation postponed.

4. _Wound of the lens._ The great safeguard against wounding the lens is to keep the point of the knife always superficial to the iris and in the periphery of the anterior chamber. If the lens be definitely wounded at the time of the operation it should be extracted immediately after the iridectomy. If the wound be only subsequently discovered (usually about the third or fourth day), provided the lens be not presenting in the wound, the eye should be allowed to settle down and the traumatic cataract extracted some time after the tenth day.

5. _Presentation of the lens in its capsule._ The lens may present in its capsule at the time of the operation or be found subsequently on the dressings. In the latter instance it is very liable to carry iris into the wound, and a cystoid cicatrix results. This accident is usually due to increased tension in the vitreous chamber; a large incision, especially if placed rather far back in the sclerotic, will also favour its occurrence. If the accident should happen to one eye, and acute glaucoma be present in the other, it is advisable to do a posterior scleral puncture before the iridectomy is performed. Partial dislocation of the lens forward may occur after the wound has healed, leaving the tension of the eye not reduced. This is a condition extremely difficult to recognize, and it is usually only discovered pathologically; if recognized clinically, extraction of the lens should be performed (Fig. 117).

6. _Intra-ocular hæmorrhage. Hæmorrhage into the anterior chamber_ occurs at the time of the operation and is readily absorbed; occasionally it may persist for a considerable time in cases of glaucoma of long standing.

After the operation hæmorrhage may also occur from the cut margin of the iris, which never heals, viz. never becomes covered with endothelium. The hæmorrhage may occur as late as two weeks after the operation and may recur from time to time; it is especially liable to occur in old people with arterio-sclerosis. It is usually absorbed without giving rise to any trouble beyond delay in the convalescence.

_Retinal hæmorrhages_ are frequent and usually small, but a considerable hæmorrhage may take place into the vitreous. As a rule these clear up satisfactorily unless the macular region be involved.

_Subchoroidal hæmorrhage._ Of all the immediate complications which follow an intra-ocular operation this is by far the worst. The hæmorrhage is due to the giving way of a large choroidal vessel following the sudden reduction of tension, with the result that the choroid and retina are stripped up from the sclerotic, and, with the lens, may be partially extruded from the wound in the globe, from which the hæmorrhage then proceeds. It may occur whilst the patient is still on the operating table, or it may be discovered only after he has been put back to bed, the blood being seen coming through the dressings. Patients who have this condition complain of pain in the ‘corner of the eye’ at the time of the operation. The treatment consists in evisceration or enucleation. It is probable that limited extravasation of blood may also occur, which need not end in disintegration of the eye, but may cause vitreous opacity and defective vision for some weeks after the operation.

=Remote.= 1. _The tension is not reduced by the iridectomy._ In acute cases the prognosis with regard to the reduction of the tension and the improvement of vision is very satisfactory. The same cannot be said of chronic cases, especially those which have been operated on rather late in the disease. If iridectomy, which may be repeated downwards or extended from the previous coloboma, fail to reduce the tension, one or more of the following measures should be adopted:--

(_a_) The use of eserine.

(_b_) Sclerotomy.

(_c_) Cyclo-dialysis.

(_d_) Sclerectomy.

(_e_) Post-scleral puncture.

It is probably in this order that they should be tried.

2. _Prolapse of the iris and irido-cyclitis_ should be treated as already indicated under cataract extraction (see p. 208).

3. _The onset of glaucoma in the other eye_ may be induced by the dilatation of the pupil caused by bandaging, and is best avoided by the use of eserine. If it should occur, an iridectomy should be performed.

4. _Astigmatism_ produced by the incision is corrected with glasses. This astigmatism is very marked, often amounting to six or eight diopters or more.

IRIDECTOMY FOR SMALL GROWTHS OF THE IRIS

=Indications.= This is performed--

(i) As a diagnostic measure. (ii) As a curative measure.

In the latter instance it is obvious that the growth must be very small and situated at the free margin of the iris to yield a satisfactory result, especially if it be of a malignant character.

=Operation.= The operation is performed under cocaine, eserine having been previously instilled in order to contract the pupil.

_First step._ An incision should be made with a narrow Graefe’s knife in the limbus in a position most suitable for removing the growth. The incision should be as large as possible so as to avoid wiping off any portions of the growth into the anterior chamber.

_Second step._ The iris should be seized well in the periphery so as to avoid breaking up the growth; it is then withdrawn with the growth, and the latter removed.

IRIDECTOMY FOR PROLAPSE OF THE IRIS

This operation is usually performed for prolapse of the iris following a wound of the cornea or limbus, and may be attempted up to about the third day after the original injury.

=Operation.= A general anæsthetic is usually desirable. The prolapsed iris should be seized with the forceps and withdrawn from the wound. A second pair of forceps is used to take a fresh hold on the iris, which can usually be drawn out further (Fig. 118). It is then divided as close to the corneal wound as possible. The iris usually flies back into the anterior chamber clear of the corneal wound by its own elasticity, but if it does not do so it should be freed with a spatula. The pupil should be kept subsequently under atropine.

TRANSFIXION OF THE IRIS

=Indications.= This operation is undertaken in cases of iris bombé when iritis is still present and when an iridectomy would subsequently lead to a drawn-up pupil. It is also of service to evacuate the contents of cysts of the iris (local iris bombé).

=Instruments.= Speculum, fixation forceps, Graefe’s knife (narrow).

=Operation.= The knife is entered at the limbus from the outer side directly opposite the occluded pupil. The apex of the iris bombé is transfixed and the point of the knife made to appear above the pupillary area; the iris bombé on the other side of the pupil is then transfixed and the knife is withdrawn.

THE DIVISION OF ANTERIOR SYNECHIÆ

=Indications.= Anterior synechiæ rarely require division unless they are likely to cause tension or the adherent iris is considered a source of danger to the eye on account of its liability to septic infection. If the synechiæ are causing tension, the method of division described under sclerotomy is probably the most satisfactory; otherwise the following method devised by Lang can be used.

=Instruments.= Speculum, fixation forceps, Lang’s knives--one with a sharp point, and one blunt.

=Operation.= Under cocaine. The incision is made at the limbus in a favourable situation for the division of the synechia. The sharp-pointed knife is introduced into the anterior chamber and then rapidly withdrawn so as not to lose the aqueous. The blunt knife is then inserted through the incision and, partly by cutting and partly by tearing, the synechia is divided in a direction from the periphery towards the pupil.

The operation is not at all easy to perform, since the iris gives before the knife. Great care should be taken to avoid evacuating the aqueous, as the operation is thereby rendered much more difficult or even impossible.