Part 38 (1/2)

=Instruments.= Giant magnet (Fig. 126), steel spatula. (Watches and magnetizable metal should be removed from both the patient and the surgeon.)

=Operation.= Under atropine and cocaine. The patient is at first seated in a chair some three feet in front of the magnet, the eyelids being held apart by the surgeon; the electric circuit is closed. The patient's head is next gradually advanced towards the magnet. If a foreign body be present in the eye and be magnetizable, the patient will usually withdraw his head or cry out with pain, and the foreign body may be seen bulging forward the iris from the posterior chamber. From this position it may be removed by manipulating the head and eye in relation to the magnet so as to withdraw it into the anterior chamber, from whence it is removed through the entrance wound or an incision at the limbus either by the giant magnet directly applied to the wound or by magnetizing a steel spatula which is inserted into the anterior chamber and connected with the magnet by a flexible steel cable. The small magnet previously described may be used, or the foreign body removed by means of iris forceps.

[Ill.u.s.tration: FIG. 126. LARGE ELECTRO-MAGNET. The current is turned on by means of the foot pedal.]

A piece of steel in the vitreous always travels round the posterior surface of the lens and through the suspensory ligament, and does not injure the lens capsule.

=Complications.= These are similar to those described under the small magnet operation.

CHAPTER V

OPERATIONS UPON THE CORNEA AND CONJUNCTIVA

OPERATIONS UPON THE CORNEA

REMOVAL OF A FOREIGN BODY FROM THE CORNEA

Removal of a foreign body from the cornea requires a good light (focal illumination). The use of a binocular lens is also of service. Foreign bodies lodged on the surface of the cornea can be removed easily under cocaine with a spud. If the foreign body be deeply embedded in the cornea a fine sterile discission needle should be used. When a foreign body, such as a chip of iron, is deeply embedded, the needle should be inserted slightly to one side of the entrance wound and pa.s.sed beneath the foreign body so as to lift it from its bed. When the foreign body has partially penetrated the anterior chamber but still lies in the cornea, an incision should be made with a keratome at the limbus and the foreign body pushed back through the entrance wound with the aid of an iris spatula. If the foreign body be iron, the electro-magnet may be of use, and in this case should be tried before resorting to an incision in the anterior chamber. A stain is left frequently after the removal of foreign bodies; this should be removed as far as possible. Subsequently the eye should be bandaged for a few days and bathed with boric lotion.

Atropine should be instilled if there be any signs of infiltration around the wound.

CAUTERIZATION OF THE CORNEA

Either a chemical or the actual cautery may be used.

=Indications.= _Corneal ulceration._ The cornea being extremely dense, organisms do not penetrate very deeply into its substance, so that destruction of the bacteria is effected by cauterization of the spreading portion of an ulcer; the alb.u.min is also coagulated and so a barrier is presented to their advance.

=Operation.= The eye is thoroughly cocainized, and the spreading portion of the ulcer is first defined by staining with fluorescine, was.h.i.+ng away the excess of stain with boric lotion.

_By a chemical caustic._ Liquefied carbolic (carbolic acid crystals liquefied in 10 per cent. of water) is applied upon a sharpened match.

Any excess should be removed so as to prevent its running on to the cornea. A speculum is inserted and the cornea is dried by blotting with cigarette paper; the stained area is lightly touched with the point of the stick, particular attention being paid to the spreading margin. A dense white plaque is the result; this usually clears up in a few days.

Atropine ointment is applied daily to the conjunctival sac.

[Ill.u.s.tration: FIG. 127. ELECTRO-CAUTERY.]

_By the actual cautery._ The electro-cautery (Fig. 127) point should be extremely fine and only raised to a dull red heat. The stained area should be touched lightly with the point.

The actual cautery is best for serpiginous corneal ulcers, carbolic acid being more satisfactory for those of the vesicular type.

OPERATIONS FOR CONICAL CORNEA

=Indications.= Since the operation for conical cornea is not without serious risks, it should only be undertaken when the vision cannot be improved with gla.s.ses to 6/18; high + or - cylinders will often yield satisfactory results. The object of all forms of operation is the flattening of the cone.

=Operation.= This may be carried out either by excision of the apex of the cone or by cauterization.

=Excision of the apex of the cone= is probably the more satisfactory method, although it is somewhat more difficult to perform. The object of the operation is to remove an elliptical portion of the whole thickness of the cornea from the apex of the cone, the long axis of the ellipse being placed horizontally. It leaves the eye with only a minute scar as compared with the nebula produced by the cautery, which is often so great as to require an optical iridectomy to restore vision.