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.

[Ill.u.s.tration: FIG. 87. SECONDARY CATARACT. Opaque capsule after cataract extraction.]

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 pa.s.sage 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 cyc.l.i.tis (kerat.i.tis 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.

[Ill.u.s.tration: FIG. 88. CAPSULOTOMY. _The method of incising the capsule._ The fulcrum of movement of the needle is where the shaft lies in the sclerotic.]

[Ill.u.s.tration: FIG. 89. CAPSULOTOMY. _The method of dividing a dense band._ This is done with two needles.]

=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 pa.s.sed into the anterior chamber from the limbus opposite to the cutting needle. The discission needle is made to pa.s.s 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-cyc.l.i.tis follow the operation.

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

EVACUATION

=Indications.= (i) In cases of increased tension a.s.sociated 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 pa.s.sed 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 pa.s.sed 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 ma.s.s.

(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 anaesthetic is usually desirable.

_First step._ The pupil is previously dilated with atropine. In the case of congenital cataract a discission needle is first pa.s.sed into the ma.s.s 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-cyc.l.i.tis 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.

[Ill.u.s.tration: FIG. 90. IRIS FORCEPS. Care should be taken to see that the teeth dovetail properly.]

[Ill.u.s.tration: FIG. 91. IRIS SCISSORS. Their cutting power should be tested on wet cigarette paper before use.]

[Ill.u.s.tration: FIG. 92. A VECTIS. It should be made of stiff steel.]

[Ill.u.s.tration: FIG. 93. PAGENSTECHER'S SPOON. It is an advantage to bend the shaft near the spoon to a right angle.]

=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 pa.s.sed on the flat into the anterior chamber from the outer side, 1.5 millimetres behind the corneo-sclerotic junction.

[Ill.u.s.tration: FIG. 94. LENS EXTRACTION. Showing the position of the hands when making a section upwards with a Graefe's knife.]

It is first directed downwards and inwards until the chamber is penetrated (Fig. 95). The knife-point is then directed horizontally and pa.s.sed 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 p.r.i.c.k 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.

[Ill.u.s.tration: FIG. 95. THE KNIFE ENTERING THE ANTERIOR CHAMBER IN CATARACT EXTRACTION. The point of the knife is directed downwards and inwards.]

[Ill.u.s.tration: FIG. 96. MAKING THE COUNTER-PUNCTURE IN CATARACT EXTRACTION. The counter-puncture is shown completed.]

=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 pa.s.ses 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.

[Ill.u.s.tration: FIG. 97. INCISION AND IRIDECTOMY IN CATARACT EXTRACTION.]