=Indications.= Enucleation should be performed in preference to Mules's operation in--

(i) Malignant tumours.

(ii) Injuries followed by cyc.l.i.tis.

(iii) Painful blind eyes.

In _malignant tumours_ enucleation should only be performed when there are no signs of extra-ocular extension. If extra-ocular extension be present, evisceration of the orbit should be performed, provided there be no evidence of general metastasis. In cases of glioma of the retina it is especially desirable that the optic nerve should be cut as far back as possible and the cross-section carefully examined for gliomatous tissue, since the disease spreads to the brain along this structure.

_In injuries followed by non-suppurative cyc.l.i.tis_ enucleation or Frost's operation is preferable to Mules's operation, since cases have been recorded of sympathetic ophthalmia following the latter operation, and it is these cases of non-suppurative cyc.l.i.tis which are especially p.r.o.ne to give rise to that disease.

_Blind painful eyes_, especially when affected with glaucoma, are best removed, as occasionally the underlying cause, when not known, may prove to be an intra-ocular growth.

=Instruments.= Speculum, fixation forceps (two pairs), straight scissors, strabismus hook, strong curved scissors.

=Operation.= Before the anaesthetic is administered the forehead should be marked over the eye to be enucleated, so as to guard against the accident of removing the wrong eye. It is usual, at any rate in the case of hospital patients, to get their written consent for the operation.

_First step._ The speculum is inserted. In the case of the right eye the conjunctiva is seized with the fixation forceps downwards and outwards, or in the case of the left eye, downwards and inwards. The straight scissors being held with the right thumb and ring finger, the conjunctiva is divided freely all the way round, as close as possible to the cornea, and dissected back.

_Second step._ The capsule of Tenon is opened below the external rectus by grasping it with forceps and b.u.t.tonholing it with the scissors. The strabismus hook is pa.s.sed through the opening made in Tenon's capsule with its concavity against the globe, turned upwards beneath the tendon, and the latter is pulled well forward and freely divided from above downwards between the hook and the globe. The superior and inferior recti are treated in a similar manner. In dividing the internal rectus a small portion should be left attached to the globe, so that subsequently it can be grasped with forceps to rotate the globe outwards when dividing the optic nerve.

_Third step._ The globe is dislocated between the lids by opening the speculum widely and pressing it backwards. If the globe will not dislocate, it is either because the tendons are imperfectly divided, or the palpebral aperture is too small to allow of its delivery; the latter is liable to be the case in small children or in those with a staphylomatous globe. In such cases the palpebral fissure should be enlarged by dividing the outer canthus.

[Ill.u.s.tration: FIG. 134. ENUCLEATION. Method of suturing the conjunctiva; the suture requires no knot.]

The _fourth step_ is the division of the optic nerve. The globe is rotated strongly outwards, either by pulling on the tendon of the internal rectus or by pulling the globe outwards with the finger; the optic nerve is felt for by pa.s.sing the strong curved scissors behind the globe. When the nerve is defined the blades are opened widely, pressed backwards, and the nerve divided. The globe is then pulled forward with the finger, and the oblique muscles and remaining attachments divided.

Haemorrhage is easily controlled by pressure and the use of adrenalin.

_Fifth step._ When the bleeding has ceased, the conjunctival wound is united in a horizontal direction by means of a thick silk suture running over and over; no knot is required and the ends are left long, so that it may subsequently be removed easily (Fig. 134). The usual dressings are applied with a firm pressure bandage for the first six hours. The suture should be removed at the end of the seventh day. No artificial eye should be worn for at least six weeks after the operation, and then only for a few hours at a time until the conjunctiva becomes accustomed to it. It should always be taken out at night.

=Complications.= These may be immediate or remote.

=Immediate.= _Cutting into the globe._ This may occur during the division of the optic nerve, and is usually due to imperfect dislocation of the globe. Although of little consequence as a rule, it may be extremely serious, as for instance in the case of an intra-ocular growth, when it is conceivable that a portion of it might be left behind. If this accident should happen, the portion of the sclerotic and choroid left behind should be carefully sought for and removed.

_Adhesion of Tenon's capsule._ Eyes that have been the subject of acute inflammation are much more difficult to enucleate, owing to adhesion of the surfaces of Tenon's capsule. In these cases the globe has practically to be dissected out of that structure.

=Remote.= _Haemorrhage_ into the stump may occur, leading to proptosis of the conjunctiva and extravasation into the eyelids and beneath the skin of the face. The use of a firm pressure bandage and the omission of the suture is usually sufficient to prevent this occurring, but the blood-clot may have to be turned out and the bleeding point sought for and ligatured.

_Granulations and polypi_ in the socket are usually the result of leaving some tag of tissue between the margins of the wound, and are therefore more likely to occur when no suture is used to close the wound. They should be removed with forceps and scissors.

_Polypoid ma.s.ses_ sometimes form in a socket as the result of an imperfect artificial eye causing an dematous condition of the conjunctiva. They should not be removed, owing to the contraction caused thereby, but the artificial eye should be left out, when they will often disappear.

_Contracted socket_ is usually the result of an imperfectly performed enucleation or loss of large portions of the conjunctiva; for the operations for its relief, see p. 261.

EVISCERATION

Evisceration is the removal of the intra-ocular contents.

=Indications.= It is the ideal operation for a suppurating globe; in these cases enucleation is contra-indicated because the lymph-s.p.a.ce round the optic nerve is opened up by the division of the latter and the inflammation may spread directly to the meninges.

=Instruments.= Speculum, fixation forceps, Beer's knife, scissors, scoop and st.i.tches.

=Operation.= A general anaesthetic is necessary.

_First step._ The eye is transfixed about 4 mm. behind the corneo-sclerotic junction with a Beer's knife, which is made to cut out upwards (Fig. 135). The flap of corneal and scleral tissue is then seized with forceps and the cornea removed entirely by completing the incision in the sclerotic round it with scissors (Fig. 136).

_Second step._ The contents of the globe are then eviscerated by means of a spoon, and the cavity flushed out with 1 in 4,000 perchloride of mercury lotion. Great care should be taken to remove all portions of the uveal tract; this is best ensured by visual inspection after the haemorrhage has ceased. The interior of the sclerotic should appear perfectly white.

[Ill.u.s.tration: FIG. 135. MULES'S OPERATION. _First step._ Excision of the cornea.]

[Ill.u.s.tration: FIG. 136. MULES'S OPERATION. The completion of the excision of the cornea with scissors.]

_Third step._ Although not absolutely necessary, and inadvisable in the case of a septic globe, a single suture may be pa.s.sed through the centre of the wound in the conjunctiva and sclerotic.

=Complications.= As the operation is not infrequently performed for panophthalmitis, much swelling of the lids and discharge from the socket may take place after the operation; these symptoms usually subside in the course of a few weeks without further trouble. The interval which must elapse before an artificial eye can be worn is considerably longer than after enucleation.

MULES'S OPERATION

Mules's operation is the insertion of a celluloid globe into the sclerotic after evisceration, followed by closure of the scleral wound over it. In both this and Frost's operation a better stump is formed, so that more movement may be obtained in the artificial eye which is subsequently worn over the inserted globe.

=Indications.= (i) The operation is especially suitable for anterior staphyloma following ophthalmia neonatorum. In young children the presence of the ball in the orbit a.s.sists the development of that structure.

(ii) It is also suitable for large, recently made, fairly aseptic wounds in the globe.

=Operation.= The _first two steps_ are the same as for evisceration.

_Third step._ A gla.s.s or, better, a celluloid or gold-plated ball is inserted into the sclerotic, which is closed over it by two rows of interrupted sutures, one of catgut pa.s.sing through the sclerotic, the other of silk closing over the conjunctival wound. To facilitate the closure of the conjunctival wound it is advisable to dissect the conjunctiva back from the limbus before excising the cornea. The ball inserted in the sclerotic should fit the cavity loosely.

=Complications.= In about 17% of the cases the ball is not retained; this is not infrequently due to too large a size being used, or to the wound being imperfectly closed by the sutures. If two rows be used, as described above, extrusion of the ball is far less frequent than if one only be inserted. If the globe be extruded the patient is in the same position as if he had had evisceration performed.

FROST'S OPERATION

In this operation the eye is enucleated, a celluloid globe is inserted into Tenon's capsule, and the conjunctiva is closed over it by means of sutures pa.s.sing through Tenon's capsule and the conjunctiva.

=Operation.= The first four steps in the operation are similar to those described under enucleation.

_Fifth step._ A small, loosely-fitting gla.s.s globe is inserted into Tenon's capsule. A purse-string suture of strong catgut is then inserted into the cut margin of Tenon's capsule, taking care to include in the sutures the cut ends of the tendons of the recti muscles. The suture is drawn tight and tied so that Tenon's capsule and the muscles are thereby drawn over the globe. The conjunctival wound is closed over this by a separate suture of silk.

The advantage of this operation over the other subst.i.tutes for simple enucleation is that it can be used after any enucleation. The chief disadvantages are that the globe is sometimes extruded unless the wound be carefully closed by sutures, and occasionally it may become dislocated from Tenon's capsule beneath the conjunctiva, thus preventing an artificial eye from being worn, and requiring removal. These disadvantages are largely done away with if the method of suture described above be used.

OPERATIONS UPON THE SOCKET AFTER THE REMOVAL OF THE EYE

PARAFFIN INJECTION

=Indications.= Occasionally after an eye has been removed the movements in the socket are not communicated sufficiently to the artificial eye which is placed over it, so that the gla.s.s eye has a fixed, staring appearance. As a rule, this can be remedied by the use of a Snellen's improved eye, which has a rounded posterior surface and fits well on to the stump. If this be not satisfactory, the injection of paraffin into the stump will often improve the movements considerably. The injection should be made by what is known as the 'cold method'.