Part 29 (1/2)
CHAPTER I
GENERAL CONSIDERATIONS APPLICABLE TO OPERATIONS UPON THE EYE
Operations upon the eye differ so widely from general surgical operations that it is necessary to say something of the preparations for them before pa.s.sing on to their actual performance. Although not formidable in themselves, they require great accuracy and presence of mind; slight mistakes, such as too small an incision, may cost the patient his sight, which sometimes may be almost more important than life itself.
Most intra-ocular operations are performed without general anaesthesia; it is therefore important that the patient should be given confidence by talking to him during the operation, so that he may follow the instructions of the surgeon during its performance; loss of self-control on the part of the patient, movement of the head, s.c.r.e.w.i.n.g up of the eyes, &c., may lead to disastrous results, however well performed the operation itself may be.
GENERAL PRELIMINARIES TO AN OPERATION
_The urine_ should always be examined, especially in cases of cataract, as not infrequently this disease is a.s.sociated with diabetes, and it is often advisable to treat the general condition before operation.
_The bowels_ should be opened by an aperient the night before the operation, as it is desirable to keep them confined for the first two days afterwards, so as to avoid straining. During the first week after a major operation, when the patient is confined to bed, they should be evacuated in the supine position.
_The best time_ for operating, if possible, is the morning, as the patient has had a night's rest and is less likely to lose self-control.
Usually there is some pain after the cocaine has gone off, and the patient is better able to stand it during the daytime.
_Anaesthetics._ _General_ anaesthesia should be induced in all patients with congested eyes, in small children, patients who are deaf, and those who show a want of self-control. Chloroform should be used for all intra-ocular operations, and should be given to the full surgical degree. It should be given on a towel or an inverted mask specially made for the purpose, a Junker's inhaler being used during the time the actual operation is being performed. As the surgeon usually stands at the head of the patient, the anaesthetist should stand on the side away from the eye being operated on. The local use of cocaine in addition to general anaesthesia is indicated when operating on patients to whom it is advisable to give as little anaesthetic as possible.
[Ill.u.s.tration: FIG. 74. WINDOW OF THE OPERATING THEATRE, KING'S COLLEGE HOSPITAL. The windows are fitted with outside blinds so that either can be used separately, or the surgeon may stand in the angle and operate with his back to the light. A recess beneath the window allows the patient's face to be brought close to the light on dark days.]
_Local_ anaesthesia is obtained by the use of a 4% solution of cocaine instilled four or five times before the operation at intervals of three minutes; a drop of the solution should also be instilled into the eye which is not being operated on, to prevent an accidental reflex stimulation of the conjunctiva and s.c.r.e.w.i.n.g up of the eyes. Adrenalin (1-1,000) may be used in conjunction with the cocaine; it is especially useful in squint operations, as it lessens the haemorrhage. Eucaine and stovaine have been used, but are not nearly so satisfactory. Under ordinary circ.u.mstances the only pain felt during an intra-ocular operation is during removal of the iris; this is obviated to a great extent by instilling the cocaine at least 15 minutes before the operation is performed, so as to allow time for its diffusion into the anterior chamber. The patient should be warned when to expect the pain, so that he may not move; his self-control may be tested beforehand by p.r.i.c.king the nose with a pin.
_The theatre._ The theatre should possess, as far as possible, all the modern improvements found in an up-to-date general surgical operating-room. The light should proceed from a single large window, which, if possible, should face the north. _The window_ should consist of a single pane of gla.s.s or of two panes forming the angle of the theatre; it should begin about 5 feet from the floor and should extend to the ceiling (Fig. 74). The advantage of an angular window is that it allows the operator to stand with his back to the light in the angle, and so enables onlookers to see. No top light should be allowed, as it produces a corneal reflection which may prevent the operator from seeing the position of his knife in the anterior chamber. Beneath the window there should be a recess for the end of the operating table, so that the patient's face can be brought close to the window if necessary (Fig.
74). This recess is formed by building the main wall of the theatre further out than the window, which has to be supported by a transverse girder.
[Ill.u.s.tration: FIG. 75. BULL'S-EYE ELECTRIC HAND-LAMP. For use when artificial illumination is required.]
The window should be fitted with outside blinds so that the theatre can be easily darkened for the operations, such as capsulotomy, which require the use of artificial light. The best artificial light is a small enclosed electric hand-lamp fitted with a bull's-eye, by means of which the operation field can be brilliantly illuminated while the surrounding area is left in comparative darkness (Fig. 75). Failing this, a single powerful lamp with a ground-gla.s.s globe, placed in front of the patient, will serve, the rays of light being brought to a focus on the eye by means of a large convex lens of about + 10 D.
For _squint operations_ it is desirable to have a light fixed to the ceiling, directly over the head of the operating table, for testing the position of the eyes either by the reflection of the light from the surface of the cornea or by the Maddox rod test.
_The operating table_ should be provided with a means of adjusting its height and the position of the head-piece, so that the patient's head can be brought to about the level of the operator's elbows when the latter is standing upright with his arms at his side.
_After operation_ the patient should be warned to lie still and not to strain in any way; he should be carried to bed and should lie on his back if possible. If a patient cannot sleep on his back it is better that he should lie on the sound side than be without rest. A length of bandage should be fastened round the wrist of the hand on the same side as the eye which has been operated upon, and should be attached to the bed so as to prevent the hand being put up to the eye during sleep.
After major operations, such as those for cataract and glaucoma, the patient is confined to bed for ten days, during the first four of which the head should not be raised from the pillow, the bowels being evacuated while the patient is in the supine position; but old patients with a tendency to bronchitis or hypostatic pneumonia must be propped up in bed and allowed to get up earlier: in these patients it is better to perform the operation in the summer if possible. In old people and patients with a tendency to melancholia the mental condition must be carefully watched, as frequently they cannot stand the confinement to bed and darkness.
LOCAL PREPARATION OF THE PATIENT
When operating upon the eye, a surgeon has to face the great difficulty that he is operating in an area which is not always aseptic, since it is practically impossible to render the conjunctival sac sterile. At the same time, the conjunctiva has been shown to be sterile in health in 25% of cases, pyogenic organisms (princ.i.p.ally the staphylococcus albus) being found only in 15%; but, although these are usually not of a very virulent character, they are by far the most frequent cause of sepsis; ten cases of suppuration after operation which the author has examined were all due to this organism. After the methods of purification given below, this percentage is considerably reduced, so that, if due precautions are taken, the risk of sepsis is comparatively small. On the other hand, if conjunctivitis or lachrymal obstruction be present, the risks are enormously increased, especially in the latter condition owing to the frequent presence of the pneumococcus in the discharge, unless special precautions are taken. It is, therefore, of the utmost importance that every case should be examined for lachrymal obstruction before operation. Care should be taken also to see that there is no purulent discharge from the nose or any septic sores about the face.
Sepsis after intra-ocular operations manifests itself in one of two forms: either by suppuration, which usually ends in a rapid and complete destruction of the eye (panophthalmitis), or more rarely in less virulent cases by recurrent attacks of hypopyon a.s.sociated with acute irido-cyc.l.i.tis; or by a plastic irido-cyc.l.i.tis, which may lead to slow disorganization of the eye, with always the possibility of destruction of the other eye by sympathetic cyc.l.i.tis (sympathetic ophthalmia).
Although these conditions are comparatively rare, owing to the improvement in modern aseptic and antiseptic methods, every surgeon of experience will meet with these disastrous complications; indeed it has been suggested that immunization with staphylococcus vaccine should be carried out before major intra-ocular operations, since infection is generally due to this organism.
[Ill.u.s.tration: FIG. 76. LANG'S EYE SPECULUM. Designed to hold the lashes away from the field of operation.]