CHAPTER II

OPERATIONS UPON THE LENS

=Surgical anatomy.= The lens consists of fibres which are developed from cells originating in an inclusion of the fœtal epiblast. A normal lens is surrounded by a capsule, the anterior half of which is lined with a single layer of epithelial cells on its inner surface. In fœtal life the cells which line the posterior half of the capsule go to form the lens fibres, so that after birth the lens capsule is lined by cells only on its anterior surface. The lens capsule, which is deposited from the epithelial cells lining it, consists of a highly elastic membrane; small wounds in its continuity, therefore, gape widely. Throughout life the cells lining the capsule continue to become new lens fibres, but at the same time the bulk of the lens does not increase markedly. This is due to the fact that the lens fibres become more closely packed together and lose some of their watery constituents (sclerosis). The older central part of the lens is the first to undergo this process, with the result that a definite hard nucleus is found in the lenses of people about the age of thirty to thirty-five and upwards.

Chemically the lens fibres are composed of crystallin, which is closely allied to a serum globulin and is therefore soluble in salt solution. When the lens capsule has been opened, by operation or accident, the saline aqueous is admitted to the lens, which becomes opaque, swells up, and is gradually absorbed (Fig. 83). In those under the age of thirty, therefore, a simple incision into the capsule is all that is required to cause it to be absorbed. But, as has already been pointed out, the lens develops a hard nucleus after that age and will not then be absorbed satisfactorily by simply opening its capsule; to remove it, as is done in senile cataract, the hard nucleus must be extracted from the eye.

The lens is held in position by the suspensory ligament, which consists of interlacing fibres attached on the one hand to the ciliary process and on the other to the capsule at the lenticular margins (Fig. 84). Prolapse of the vitreous after cataract extraction is prevented by the integrity of this ligament and the posterior capsule of the lens, together with the hyaloid membrane of the vitreous. The tension on the fibres of the suspensory ligament, in addition to keeping the lens in its place, also exercises traction on the lens capsule. In dislocated lenses there is a gap in the suspensory ligament either as the result of injury or of congenital malformation; when such cases require operation there is some difficulty in producing a sufficient gap in the capsule to promote their absorption, owing to the mobility of the lens and the want of traction on the incision in the capsule.

DISCISSION OR NEEDLING

Discission of the lens has for its object the tearing open of the anterior capsule, so that the lens substance may be broken up and absorbed.

=Indications.= This operation will be required:

(i) =For cataract in patients under the age of about thirty.= The forms of cataract for which these operations are usually performed are: (i) _complete congenital cataract_, in which the whole lens is opaque and consists of little more than a shrunken capsule which may have to be extracted if discission is unsuccessful; (ii) _lamellar cataract_, of sufficient density to interfere seriously with vision; (iii) _posterior polar cataract_ in rare instances; (iv) _traumatic cataract_, to complete the absorption of the lens by breaking up its fibres.

Before operating on any form of cataract the following facts must be ascertained as far as possible:--

(_a_) _Vision._ It must be remembered that in children a defective eye retaining the power of accommodation is often more useful than an eye which sees better but has to wear different glasses for different distances. Vision must be reduced to less than 6/18 in both eyes after correction with glasses before the operation should be undertaken. In rare cases, in children, and in traumatic cataract where the cataract is very dense and confined to one eye, it may be removed partly to improve the personal appearance and partly to enable the patient to see large objects.

An eye without a lens (aphakia) will not work with an eye with a lens even if the former be corrected with glasses.

If the patient be unable to see letters, he should have a ready and quick perception of light, no cataract, however dense, being sufficient to prevent this.

(_b_) A patient should have a good _projection of light_; that is to say, he should be able to locate the light when thrown into the eye with a mirror whatever direction it comes from. Children generally turn the head towards the light, provided that they can see it and that the eye is not defective from other causes.

(_c_) Note whether _the pupils_ are equal and active. In children most useful information can often be obtained as to the condition of the fundus by means of the pupil, which often will not react when the patient is unable to appreciate light.

(_d_) _The condition of the fundus of the other eye_, if observable, should be taken into account, as many diseases of the fundus, such as choroiditis and myopia, are bilateral, and would influence the prognosis considerably.

(_e_) _The lachrymal sac_ and conjunctiva should be free from all signs of inflammation (see p. 181).

(ii) =For the removal of a lens for high myopia.= In selected cases operation gives very satisfactory results with great improvement of vision; indeed full normal distance vision has been obtained without glasses. The operation, however, is only justifiable under certain circumstances, the chief of which are:--

(_a_) The amount of myopia should exceed 18 D. (_b_) Distance vision should be defective--less than 6/18 with glasses. (_c_) Ophthalmoscopically the macular region should be sound. (_d_) Binocular vision should be absent. (_e_) The patients should be children or young adults. (_f_) If there is some serious reason why the patient is unable to wear glasses.

In emmetropia, if the lens be removed, a glass of + 11 D. has to be placed before the eye for distance vision and + 14 D. for near vision. It is impossible to predict the exact amount of correction of myopia which will be produced by the removal of the lens, owing to the surgeon’s inability to estimate the refractive power of the lens associated with the distortion of the posterior pole of the globe. Usually a patient with about 22 D. of myopia is rendered emmetropic by the operation.

There are two main objections which have been raised to the operation: first, that there is a slight risk of septic infection, sympathetic ophthalmia even having been known to occur; secondly, that retinal detachment seems rather more common after operation than in ordinary myopia of the same degree. As a rule it is only advisable to perform the operation on one eye, the patient using the other for reading purposes, but under certain circumstances, as when the operation has been successful for a considerable period of time, it would be justifiable to perform it on the other eye. The operation should never be performed on patients having only one eye.

=Instruments.= Speculum (Fig. 85), fixation forceps (Fig. 86), discission needle.

=Operation.= _First step._ The operation is best performed by artificial light. The pupil having been dilated with atropine and the eye anæsthetized with cocaine (a general anæsthetic being necessary, however, for young children), the speculum is inserted by first drawing up the upper lid, making the patient look down, and inserting the top blade, and then drawing down the lower lid, making the patient look up, and inserting the lower blade. The speculum is opened to its full width without undue strain on the canthus and is kept in position by tightening the screw. The eye is steadied by fixation forceps held in the left hand, which grasp the conjunctiva as close to the cornea as possible directly opposite to the spot at which the puncture is to be made; the puncture is made directly behind the limbus and the needle is passed into the anterior chamber.

_Second step._ Using the shaft of the needle lying in the cornea as a fulcrum on which to rotate the needle, an incision is made in the anterior capsule of the lens, and the lens fibres are broken up by a stirring movement. The needle is then rapidly withdrawn in the same plane in which it was inserted so as to avoid making a crucial incision in the cornea with the spear-like end and thereby losing the aqueous. The best way to make sure of this is to mark one side of the handle so that it may be inserted and withdrawn in the same position. A pad and bandage are then applied.

=After-treatment.= The pupil should be kept dilated subsequently by the use of atropine twice a day until the lens has become absorbed. The bandage may be removed about the fourth day and dark glasses worn.

The effect of the operation on the lens varies considerably. It may swell up so rapidly that the tension of the eye becomes increased, in which case an evacuation may have to be performed; in other cases, especially in the cases of a patient with high myopia, several needlings may be required before absorption is complete.

CAPSULOTOMY

Capsulotomy is the division of the opaque capsular membrane left after a cataract has been removed.

=Indications.= After a cataract has been removed, either by discission or extraction, an opaque membrane is usually left. This is due to the proliferation of the cells in the anterior capsule of the lens while attempting to lay down new lens fibres. Although the posterior capsule is clear and free from cells, those from the anterior capsule may spread to it and so render it opaque. A fibrinous exudate may also organize and help to thicken the membrane (Fig. 87). For these reasons and also because the soft matter may not have absorbed entirely, it is not advisable to operate too soon after a cataract has been removed. There should be at least six weeks’ interval after an extraction has been performed. A few surgeons operate earlier than this, the idea being that the membrane is then softer and more easily divided.

Although the operation of discission for after-cataract (capsulotomy) is simple it is not to be undertaken lightly. The patient’s vision should be less than 6/18. In former days the operation was looked upon as attended with as much risk as the extraction, owing to the frequency with which it was followed by inflammation. The reasons for this seem to have been want of proper antiseptic precautions, the passage of the needle through the non-vascular corneal tissue instead of through the conjunctiva, and also the use of a badly made needle, often resulting in prolapse of the vitreous into the wound. A proper discission needle should have sufficient width in its spear-like point to cut a hole large enough to admit the shaft freely; hence needles which have been sharpened several times should be discarded. It need hardly be said that there should be no signs of cyclitis (keratitis punctata) present when the operation is undertaken.

=Instruments.= These are the same as for discission, with the addition of a needle with a long cutting edge.

=Operation.= Capsulotomy is best performed by artificial light under cocaine. The cutting needle is inserted into the anterior chamber as in the previous operation. The point is then thrust through the membrane below (but it should not penetrate deeply, otherwise the vitreous will be torn) and an incision is made in an upward direction. This incision usually gapes sufficiently to give a clear pupil (Fig. 88). Those surgeons who operate early try to cut out a triangular portion of the membrane. When a dense band is present which gives before the needle and cannot be divided, a second or ordinary discission needle should be passed into the anterior chamber from the limbus opposite to the cutting needle. The discission needle is made to pass behind the band whilst the cutting needle lies in front of it. By a rotary movement of the discission needle around the cutting needle the band is carried against the edge of the latter and so divided. The needles are then withdrawn (Fig. 89).

=Results.= These are good as a rule, but the operation may have to be performed again owing to an insufficient or non-central opening being obtained in the membrane, or to a fresh membrane forming; this is liable to take place if any irido-cyclitis follow the operation.

=After-treatment.= This should be carried out as described for needling.

EVACUATION

=Indications.= (i) In cases of increased tension associated with soft lens substance in the anterior chamber.

(ii) To accelerate the absorption of soft lens matter from the anterior chamber. As a rule it is only undertaken for the former condition.

=Instruments.= Speculum, fixation forceps, bent broad needle, curette.

=Operation.= Under cocaine.

_First step._ An incision is made behind the limbus, usually in an upper segment of the cornea, by means of a bent broad needle. The point of the instrument is passed into the anterior chamber immediately behind the limbus with the handle at right angles to the cornea; directly the anterior chamber has been entered the handle is depressed so that the point of the instrument shall turn forwards and avoid injuring the iris. The blade is passed on into the anterior chamber until the point reaches about the centre of the pupil. It is then either withdrawn directly, or, if a larger incision be desired, lateral pressure is made so that in withdrawing the blade the wound is enlarged.

_Second step. Evacuation._ With the rush of aqueous which follows the incision some soft matter is usually evacuated; then a curette may be introduced, if necessary, and the lens fragments removed by gentle manipulation. Occasionally the iris may prolapse into the wound; if this happens it should be replaced, but if it occur more than once the prolapsed portion should be removed. Suction apparatus has been used for removing the soft lens matter, but it is not to be recommended in most cases, owing to the difficulty of sterilization and the trauma which it may cause. After-treatment as for needling should be carried out.

EVULSION OF THE CAPSULE

=Indications.= (i) In congenital cataract when the lens consists of little more than a dense capsular mass.

(ii) In dense capsular membranes following removal of a lens by discission in which a cutting needle cannot make a hole.

=Instruments.= Speculum, fixation forceps, keratome, capsule forceps, discission needle.

=Operation.= A general anæsthetic is usually desirable.

_First step._ The pupil is previously dilated with atropine. In the case of congenital cataract a discission needle is first passed into the mass to estimate its consistency. If it consist of little more than capsule an incision is made at the limbus with the keratome as described for evacuation.

_Second step._ The blades of the capsule forceps are then inserted closed, opened, and the opaque capsule grasped and withdrawn from the eye. The speculum is then removed and a pad and bandage applied. The pupil should be kept dilated with atropine subsequently, as a certain amount of irido-cyclitis following the operation is not infrequent. Occasionally the iris may become entangled in the wound, and it should then be removed.

EXTRACTION OF THE LENS

=Indications.= (i) For all forms of cataract in patients over thirty years of age.

(ii) For cases of high myopia over the same age.

(iii) For lenses containing foreign bodies.

(iv) For displacement of the lens causing irritation.

Probably no operation in surgery has so many modifications, many of which possess advantages and disadvantages which counterbalance each other so nearly that the individual surgeon must decide for himself which is the most satisfactory to carry out. The opinion of many surgeons, including the author, is that the ideal operation is one which can obtain sight for the patient at one sitting. The operation described below is carried out with this object in view, the various modifications and the indications for their use being subsequently discussed.

_Instruments._ Speculum, two pairs of fixation forceps, a Graefe’s knife, iris forceps (Fig. 90), iris scissors (Fig. 91), capsule forceps, cystotome, curette or spoon, iris spatula, vectis (Fig. 92), or lens spoon (Fig. 93).

=Operation.= The operation is performed under cocaine and is divided into five steps:--

1. Incision. 2. Iridectomy. 3. Opening the lens capsule. 4. Delivery of the lens. 5. Toilet of the wound.

=First step.= _The incision._ The surgeon, standing behind the patient’s head and holding the knife with the edge directed upwards, in the right hand for the right eye and in the left hand for the left, fixes the eye with a pair of forceps held in the other hand, by grasping the conjunctiva below and to the inner side as close to the limbus as possible (Fig. 94). Most continental surgeons stand in front of the patient and cut upwards. The point of the knife is then passed on the flat into the anterior chamber from the outer side, 1.5 millimetres behind the corneo-sclerotic junction.

It is first directed downwards and inwards until the chamber is penetrated (Fig. 95). The knife-point is then directed horizontally and passed across the anterior chamber in a line parallel with an imaginary tangential line across the top of the cornea. The counter-puncture is then made, the knife emerging 1 millimetre behind the corneo-sclerotic junction (Fig. 96). In making the counter-puncture the beginner is apt to go too far back in the sclerotic owing to the angle of the chamber being placed behind the limbus; he should therefore aim for a point about 1 millimetre inwards from the limbus. The knife is next made to cut upwards by a sawing movement so that a flap is formed of corneal tissue about 3 millimetres in breadth (a breadth and a half of a new Graefe’s knife), the upper margin being at the corneo-sclerotic junction. When the corneal flap has been made, the knife should lie beneath the conjunctiva, from which a flap about 3 or 4 millimetres in length should be formed. The knife-edge is then turned forward and made to cut its way out. In making the section, care must be taken not to prick the patient’s nose or eyelid with the point of the knife, as it may cause him to move his head with disastrous results. This is more likely to happen with patients who have sunken eyes.

=Second step.= _Iridectomy._ The patient is made to look downwards. A pair of iris forceps are inserted, closed, into the anterior chamber, opened, and the iris grasped near its root, and withdrawn. The piece of iris is then removed with the iris scissors, dividing it parallel with the incision as close to the eye as possible (Fig. 97). If the conjunctival flap hinders the insertion of the iris forceps into the anterior chamber, it may be turned forward over the cornea with the point of the closed forceps.

=Third step.= _The capsule of the lens is opened._ This is done in order to allow the lens nucleus and soft matter to escape. Since the anterior capsule becomes opaque after the removal of the lens, owing to the multiplication of the cells in their attempt to lay down new lens fibres, it is desirable to remove a portion of the anterior capsule from the pupillary area. This may be performed (_a_) by means of capsule forceps which are inserted closed, and when in position over the lens are opened as widely as possible without entangling the iris, then pressed down on to the anterior capsule of the lens and closed; in this manner the portion of the capsule thus included is removed by a slight lateral movement (Fig. 98); (_b_) by means of a cystotome, the lens capsule being opened by a triangular or T-shaped incision over the pupillary area; (_c_) by the point of the knife as it passes across the anterior chamber; (_d_) by a discission needle before the section is made. When the capsule of the lens has been opened properly the lens nucleus is usually seen to come forward. The advantage of the capsule forceps over the other methods is that they remove a larger portion of the capsule and leave no tags which may become incarcerated in the wound. On the other hand they are somewhat more difficult to use; more pressure on the lens is required, and therefore dislocation of the lens in its capsule may result. It is, therefore, not advisable to use them in cases in which a fluid vitreous is suspected. If the teeth of the forceps are not well made they will not grasp the capsule; it is therefore always advisable to have the cystotome in readiness. The cystotome also should be used when the anterior chamber becomes filled with blood so that the margin of the iris cannot be seen and there is a risk of the iris being grasped by the forceps.

The method of opening the capsule with the point of the knife or needle is useful in cases of extraction without iridectomy; the pupil should be dilated before the operation.

=Fourth step.= _Delivery of the lens_ is performed by a gentle pressure, combined with massage, on the extreme lower margin of the cornea with a curette or spoon, until the upper margin of the lens presents in the wound, when the pressure is gradually made upwards over the cornea until the lens is delivered. Delivery of the lens may be prevented by--

(_a_) Imperfect opening of the capsule, which is usually the result of using a blunt cystotome; if capsule forceps are used this difficulty hardly ever arises.

(_b_) Too small an incision. The margin of the nucleus may present and not be able to pass the wound. The wound must then be enlarged with the iris scissors and the lens delivered in the ordinary way. Only by experience can the amount of pressure required for the delivery of the lens be gauged.

(_c_) A sticky consistency of the cortex is not infrequently found in cases of immature cataract. When the lens presents and cannot be delivered readily it may be helped out by means of the cystotome plunged into its substance, pressure being used on the cornea at the same time.

If from these or any other causes the suspensory ligament rupture and the vitreous present in the wound, the lens should be removed with the vectis. The vectis, which should be made of stiff steel, is passed vertically into the incision and behind the lens nucleus by depressing the handle; with a steady gentle pressure forwards it is then withdrawn together with the nucleus. The forward pressure should be such as to prevent the instrument slipping on the nucleus, for if it does so the accident is nearly always followed by a rush of vitreous. A Pagenstecher’s spoon may be used instead of the vectis, and is to be preferred in cases where a small nucleus is suspected, since the latter may slip through the loop of the vectis and fail to be delivered.

=Fifth step.= _Toilet of the wound._ After the nucleus has been extracted, all the soft matter should be removed as far as possible by gentle expression with the spoon. The angles of the coloboma in the iris should be replaced by stroking it inwards on its anterior surface with the iris spatula, paying particular attention to the angles of the wound (Fig. 99). The spatula should also be passed throughout the extent of the wound so as to free it from any capsule which may have prolapsed into it. The conjunctival flap is then placed in position by stroking it upwards with the iris spatula.

=After-treatment.= Atropine is instilled either at the time of operation or at the first dressing, and continued until all signs of redness of the eye have disappeared. The patient should remain in bed for at least ten days, both eyes being bandaged during the first four days. The eye that has been operated on should be covered for at least two weeks; subsequently a shade or dark glasses should be worn.

=Modifications.= The operation may be modified in various ways.

=The incision.= _The position_ of the incision has undergone many modifications. The one described above is now in general use.

_The size_ of the incision should be increased when (_a_) a large nucleus is expected, as in old people; (_b_) an immature cataract is to be extracted; or (_c_) a fluid vitreous is suspected, so that the lens may be delivered with as little pressure as possible.

=The iridectomy= may be omitted. _Extraction without iridectomy_ is undoubtedly the ideal operation; it leaves the pupil unbroken and the eye looking normal to external appearance. Further, the pupil reacts more strongly to light than if an iridectomy has been performed. The presence of the iris further prevents the prolapse of any capsule into the wound. At the same time it is attended with considerable risk of prolapse, which, as has been pointed out, is a very great danger to the eye. With proper care this probably only occurs in about 5% of the patients operated upon, but is so serious that the opinion of most surgeons is in favour of the combined method (iridectomy and extraction); but at the same time it is the practice of many surgeons to omit the iridectomy under the following circumstances: first, if the patient be young and the deformity will interfere with his getting employment; secondly, if extraction of the lens in its capsule be performed the unbroken circle of the iris will help to prevent the prolapse of the vitreous which is otherwise so liable to take place.

Eserine (gr. ii ad ℥i) should be used to prevent prolapse of the iris after the extraction has been performed, and should be continued once a day until a good anterior chamber is present, which is usually in about twelve to twenty-four hours, when atropine should be substituted. If the iris betray any liability to prolapse after the operation, as shown by the drawing upwards of the pupil, an iridectomy should be performed before the patient leaves the table. In any case the eye should be examined on the evening of the operation, and, if prolapse has occurred, that portion of the iris should be removed. If a prolapse of the iris occurs and is not discovered until the wound has healed, the conjunctiva should be dissected off the surface in the form of a flap and the iris tissue drawn out of the wound and removed, the angles caught in the scar being freed if possible. The opening in the globe is subsequently closed by replacing the conjunctival flap in position, or, if it has not been possible to preserve the conjunctiva over the cicatrix, by raising a flap from the ocular conjunctiva in the neighbourhood and stitching it down over the opening in the globe. Not infrequently this operation is followed by an attack of acute iritis, which usually subsides under treatment.

_Preliminary iridectomy._ The iridectomy may be performed at a previous operation. It has the advantages that the surgeon learns how the patient will behave under operation, and how the eye will react to such an operation. There is an absence of bleeding at the second operation, which makes it easier, and there is less liability for the iris to become adherent to the capsule. The disadvantages, which seem to outweigh the advantages, are that there is a double chance of sepsis, and that the patient has to submit to two operations when one is sufficient. It is only performed by the author in cases in which there is a tendency to increased tension in the eye due to swelling of the lens in the early stages of the cataract. When a preliminary iridectomy is performed a keratome may be substituted for the Graefe’s knife in making the incision for the iridectomy, a much smaller one being necessary.

=Delivery of the lens by irrigation.= McKeown removes the soft lens matter by a process of irrigation into the anterior chamber, a practice not yet much adopted, but of considerable service in removing the soft matter after the extraction of the nucleus, especially in immature cataract. It is also probable that the thorough removal of the soft lens matter by this method reduces the number of cases of cyclitis following the operation, since the soft matter forms a suitable medium for the growth of organism. The apparatus used is shown in Fig. 100, nozzle No. 2 being the most useful; it is inserted into one angle of the wound and a stream of sterilized normal saline solution at 39°C. (in the flask) is allowed to flow into the anterior chamber; this stream is obtained by raising the flask until sufficient pressure is obtained. An undine may be substituted for the flask. Care should be taken that there is a free return of fluid from the anterior chamber; irrigation should be continued until as much as possible of the soft matter has been removed.

=Extraction of the lens in its capsule.= This operation is frequently performed in India, where patients will often not return for needling of secondary cataract (capsulotomy). Although the method undoubtedly yields good results, the percentage of eyes damaged by loss of the vitreous must be higher than when the posterior capsule of the lens is left intact. The operation may be performed with or without an iridectomy, the lens being removed by pressure on the cornea with a large strabismus hook. If the vitreous should present, the lens should be removed with the vectis.

Extraction of the lens in its capsule is also performed when the lens is dislocated and causing irritation. If the lens be in the anterior chamber immediate extraction is called for, as glaucoma is a usual complication. Eserine is first instilled in order to contract the pupil and prevent the lens passing back into the posterior chamber; an incision is then made as for a cataract extraction and the lens removed by means of the vectis. Complete dislocation of the lens into the vitreous rarely requires operation, as the patient is able to see. Partial dislocation (luxation) occasionally calls for extraction, the vectis usually being employed for delivering the lens, but before undertaking the operation an attempt should be made to get the lens into the anterior chamber by dilating the pupil and making the patient lie face downwards; if this is successful eserine should be instilled to contract the pupil behind the lens and so retain it in the anterior chamber, from whence it can more easily be extracted. Some surgeons prefer to fix the lens with a needle passed through the sclerotic behind the ciliary body before making the incision.

=Subconjunctival extraction.= In order to diminish the risks of sepsis, more especially in cases in which the conjunctiva is affected with trachoma, some continental surgeons deliver the lens into a pocket beneath the conjunctiva, whence it is subsequently removed. The operation has the additional advantage of a better blood-supply to the corneal flap, which is also held in better position after the operation.

_Operation._ A section upwards is made with a Graefe’s knife as in the ordinary method of extraction previously described, the lens capsule being opened with the point of the knife as it is passed across the anterior chamber. When the section through the sclerotic has been completed and the knife lies entirely beneath the conjunctiva it is withdrawn.

The wound in the conjunctiva on the outer side is then enlarged upwards with scissors, and an iris spatula is passed beneath the conjunctiva from the small wound on the inner side and the point made to appear in the wound on the outer side; by this means the conjunctiva is raised on the spatula, and by means of sharp-pointed scissors a pocket is made in an upward direction by undermining the conjunctiva (Fig. 101). Delivery of the lens is then performed into this pocket, from which it is subsequently removed, the conjunctival wound on the outer side being closed with a stitch. The advantage of this form of subconjunctival extraction over other forms which have been devised is that if difficulty is met with in delivering the lens, &c., the operation can be readily converted into an ordinary extraction by completing the division of the conjunctival flap.

=Complications.= These may be immediate or remote.

=Immediate.= 1. If the knife-point become entangled in the iris as it is passed across the anterior chamber it should be slightly withdrawn, if this can be done without loss of aqueous, the iris being thereby disengaged.[4]

[4] For the other complications which may arise in passing a Graefe’s knife across the anterior chamber, see Glaucoma Iridectomy, p. 222.

2. _Loss of the aqueous before the section is complete_ may result in the entanglement of the iris as before described, or the iris, owing to the presence of the aqueous in the posterior chamber, may bulge forward in front of the knife-blade. The latter complication is more likely to occur if the section be made too rapidly. The iris may sometimes be disengaged by depressing the handle of the knife towards the patient’s chin and raising the blade towards the cornea so as to allow the aqueous in the posterior chamber to escape. If this cannot be accomplished, the section should be completed and the iris, which may be divided by the knife, removed subsequently when doing the iridectomy.

3. _Avulsion of the iris_ due to movement of the patient’s head. This is more liable to take place if the eye has not been properly cocainized some time before the operation. The grasping of the iris by the forceps is always felt by the patient to a certain extent, and he should be warned not to move. Avulsion is usually not complete and only results in a larger iridectomy than was intended.

4. _Dislocation of the lens._ (_a_) When opening the capsule, either from too great pressure of the capsule forceps, or from the patient moving his head. The lens must then be delivered by the vectis. (_b_) If, in delivering the nucleus, the upper edge is not made to present by pressure on the lower part of the cornea, the nucleus, especially if it be small, is liable to be dislocated upwards beyond the incision. It must then be removed with the vectis. In cases where a small nucleus is suspected, pressure should be made on the sclerotic above the incision with a curette, as well as on the lower part of the cornea, so as to make the nucleus present in the wound.

The lens may be dislocated backwards into the vitreous; if this should happen and the lens cannot be delivered, the flap must be replaced in position and the eye bandaged. Unfortunately this complication is usually followed by irido-cyclitis and loss of the eye.

5. _Loss of the vitreous._ There are two chief phenomena which may indicate that loss of vitreous is about to take place after the extraction of the lens.

(_a_) The wound gapes unnaturally after the expulsion of the lens, and the clear vitreous may be seen presenting in the wound in the still unruptured hyaloid membrane.

(_b_) There may be an apparent deepening of the anterior chamber owing to the fluid vitreous making its way forward through the ruptured hyaloid into that cavity.

If the vitreous presents in the wound before the lens has been removed, the latter should be delivered as rapidly as possible by the vectis, as has previously been described.

If the vitreous be lost or one of the phenomena previously mentioned occurs after the delivery of the lens, the speculum should be removed from the eye and the conjunctival flap replaced in position as quickly as possible. The eyelid is then carefully raised from the surface of the eyeball by means of the lashes held in the finger and thumb and carried downwards over the globe until it is in the closed position, and a bandage is then applied.

As little manipulation as possible should be carried out when once the vitreous has shown itself about to present, and unless the iris be obviously in the wound no attempt should be made to replace it.

Loss of vitreous may be the result of subchoroidal hæmorrhage, which may only make itself manifest after the patient has been put back to bed.

Loss of vitreous is frequently accompanied by hæmorrhage into the vitreous, as is seen subsequently by the floating opacities therein. As a rule these clear, and useful vision is obtained.

Detachment of the retina may follow loss of vitreous even months after operation. This complication seems more liable to occur if the vitreous which is lost in the first instance be normal and not of the fluid type.

6. _Intra-ocular hæmorrhage_ (see Glaucoma Iridectomy, p. 224).

=Remote.= 1. _Panophthalmitis_ is a result of infection of the wound. It usually makes its appearance about the third day and must be treated by evisceration. Occasionally the purulent material is limited to the line of the incision or even to the anterior chamber; in the latter instance the wound should be opened up and the anterior chamber washed out with peroxide of hydrogen solution (10 vols. %). Microscopic examination of the pus should be made and a vaccine prepared and administered; in two cases so treated by the author a good recovery resulted.

2. _Escape of the aqueous beneath the conjunctiva_ usually occurs about the third day, owing to the conjunctival wound having healed without the opening into the globe being properly shut off. This is accompanied by considerable pain, with chemosis and some œdema of the upper lid. It is usually distinguishable from acute iritis by the pupil being evenly dilated and discoloration of the iris being absent. The condition usually subsides in three or four days, when the wound in the globe has become shut off.

3. _Acute iritis_ not infrequently occurs after extraction. It usually comes on about the third day and may be accompanied by hypopyon. It may settle down under atropine, leeching, and dry heat, but may also pass on into the more chronic form; adhesion of the iris to the capsule, however, frequently results. More rarely the disease may not make its appearance till two or three weeks after the operation (latent sepsis), the patient suffering from recurring attacks of hypopyon. In these cases in which the hypopyon persists, washing out the anterior chamber with peroxide of hydrogen (10 vols. %) and the administration of a vaccine is of service.

4. _Chronic irido-cyclitis_ is usually primary, but may occasionally follow an acute attack of iritis. Of all the disastrous complications, this is by far the worst. It may not only destroy the sight of the eye on which the operation has been performed, but may set up sympathetic ophthalmia in the other eye. The eye does not settle down well after the operation, there being usually some prolapse of the iris or capsule into the wound. It remains injected or flushes up on exposure to light. After a time (usually about the end of the third week) keratitis punctata makes its appearance, and the tension of the eye may become decreased or occasionally increased. The disease may resolve or go on to shrinking of the globe. Energetic treatment with atropine and hot fomentations locally, with the internal administration of iron, is indicated. The administration of staphylococcus vaccine causes only temporary improvement in most instances. In six cases so treated by the author the improvement was only temporary, in spite of the fact that there was a definite local reaction to the vaccine and in two cases the staphylococcus albus was isolated from the fluid in the anterior chamber. If at the end of two months the eye be red and well-marked keratitis punctata be present, and if the pupil be beginning to be drawn up and the eye shows no tendency to improve, enucleation should be seriously considered; this is especially advisable if the projection of light has become defective, showing that the retina is probably detached. If any signs of sympathetic irritation, such as mistiness of vision, ciliary flush, or photophobia, appear in the eye which has not been operated on, the exciting eye should be enucleated. On the other hand, if well-marked inflammation has developed in the sympathizing eye, which may also be cataractous, and the other eye has a fair amount of vision, it becomes extremely questionable whether it is advisable to enucleate the exciting eye. Every case must be judged on its own merits according to the extent and severity of the disease. In a few cases in which the incarceration of the capsule in the wound leads to a very chronic cyclitis, its division with a cutting needle will sometimes lead to subsidence of the inflammation. It is most important that every eye that has been operated on should be examined for the presence of keratitis punctata, especially before allowing the patient to use the eye or before another operation is performed on it.

5. _Glaucoma_ following extraction occurs as a result of (_a_) soft lens matter blocking the angle of the anterior chamber. As a rule the tension will usually subside under eserine, but evacuation of the anterior chamber (see p. 233) may have to be performed; on the whole the results are satisfactory. (_b_) The incarceration of the capsule in the wound, pulling forward the iris and blocking the angle of the anterior chamber. Division of the lens capsule is usually sufficient to make the tension subside. Failing this, sclerotomy should be performed; the prognosis is not nearly so good when the increased tension is due to this cause.

6. _Striate keratitis_ usually makes its appearance on the second or third day after operation. The cornea near the line of incision presents a grey striped appearance with the striæ arranged at right angles to the wound. Pathologically the condition is due to an infiltration of the deeper layers of the cornea, the striped appearance being caused by wrinkling of Descemet’s membrane; the condition probably arises from septic infection. As a rule the affection subsides without giving rise to further trouble, but occasionally local suppuration and even panophthalmitis may follow.

A grey horizontal line about the centre of the cornea is sometimes seen after an eye has been too tightly bandaged; this always disappears when the bandage is removed.

7. _Erythropsia_ (red vision) occasionally follows the extraction of the lens, and is probably due to bleaching of the visual purple following the admission to the eye of an unusual amount of light; it usually disappears in a few weeks.

8. _Defective vision._ Glasses have to be worn after removal of the lens. Usually patients who were previously emmetropic require about + 11 to see clearly for distance and + 15 for near vision.

The section produces some flattening of the corneal curvature at right angles to the line of the incision; this usually amounts to about two diopters.

COUCHING

Couching is the removal of the lens from the pupillary area by depressing it backwards into the vitreous. It is rather a relic of the past than a present-day operation, although it is extensively practised by quacks in India. Under certain circumstances the operation still seems justifiable; it is very simple, and is followed by immediate restoration of vision, but the subsequent risks of irido-cyclitis, retinal detachment, and glaucoma are so great, that, according to some authorities, couching should only be undertaken in preference to extraction when the latter operation has only a chance of one in three of giving satisfactory vision.

=Indications.= The chief indications for its performance are:--

(i) The presence of a fluid vitreous, the patient having had the lens of the other eye extracted with bad results.

(ii) In the insane, where it would be impossible to carry out the after-treatment of extraction satisfactorily.

=Operation.= The operation is usually done under cocaine; in the case of the insane a general anæsthetic is usually necessary. It has been performed by simple depression of the lens backwards into the vitreous with a needle passed through the cornea (anterior route). This operation yields unsatisfactory results owing to the lens being liable to return into the pupil; this can be partly overcome by sweeping the needle round the periphery of the lens so as to divide the suspensory ligament, but the operation is not so satisfactory as when the needle is passed in from behind the ciliary body and the lens pressed down from behind (posterior route), to which the following description applies. The capsule of the lens should be torn freely, so that some absorption may subsequently take place and diminish the risk of complications.

=Instruments.= Speculum, fixation forceps, needle.

_First step._ The pupil should be dilated with atropine. The patient’s head should be well raised on the table. The needle is passed through the sclerotic about 5 millimetres behind the limbus to the outer side. The posterior capsule of the lens is then freely divided by a sweeping movement.

_Second step._ The needle is next made to appear in the lower part of the pupil by carrying it round the lower and outer border of the lens. The anterior capsule is then freely divided.

_Third step._ The shaft of the needle is laid flat on the surface of the lens towards its upper part, and by raising the handle of the needle the lens is displaced backwards into the vitreous. The tearing of the suspensory ligament on the inner side may be assisted by the cutting edge of the needle during depression.

=Complications.= _Immediate._ Difficulty may be experienced in making the lens lie at the bottom of the vitreous, and it is only by frequent depression of the lens backwards and downwards, with a sweeping movement of the needle to divide the suspensory ligament, that the desired effect can be obtained.

_Remote._ The lens nucleus may prolapse through the pupil into the anterior chamber. If this should happen, the patient should be placed on his back and the pupil dilated with atropine; if the nucleus does not go back into the vitreous chamber it should be depressed by means of a needle passed through the cornea.

Glaucoma may result from the dislocation of the nucleus into the anterior chamber and should be treated as described above. It may also be present with a lens which is dislocated backwards. This condition is very liable to end in loss of sight. Probably the only hope of relieving the tension is by the use of eserine or the performance of a cyclo-dialysis.

Cyclitis and retinal detachment may also follow, and usually end in blindness.