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 passed 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 albumin 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, washing 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.

_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 glasses 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.

=Instruments.= Speculum, fixation forceps, a narrow Graefe’s knife, straight iris forceps, and scissors.

The operation is done under cocaine, atropine having been previously instilled.

_First step._ The apex of the cone is transfixed by the Graefe’s knife with the blade directed slightly upwards and forwards, the knife being made to cut out. The cornea in this situation is extremely thin, being often not more than 1 mm. in thickness. The length of the incision should not exceed 2 mm.

_Second step._ The flap of corneal tissue thus made is seized with the straight iris forceps and removed with iris scissors, producing a small elliptical opening. The chief difficulty of the operation is the seizing of the corneal flap, which is most difficult to hold; care must be taken not to injure the lens capsule with the iris forceps or scissors when the cornea has collapsed as the result of the evacuation of the anterior chamber. The eye should be firmly bandaged subsequently, and the patient kept in bed until the anterior chamber has re-formed.

=Complications.= _Slow re-formation of the anterior chamber._ The anterior chamber will often take two or three weeks to re-form, owing to the hole in the cornea not closing. During this time the eye is open to septic infection and therefore the greatest care should be taken to keep it aseptic when dressing it. For this reason and also because the following complications are due to the same cause, it is desirable to remove as little corneal tissue as possible in performing the operation. It is probable that conjunctivoplasty (see p. 245) would considerably facilitate the rapid closure of the wound.

_Anterior polar cataract_ may result from prolonged contact of the lens with the wound in the cornea. As a rule this seldom interferes much with vision.

_Anterior synechiæ_ from incarceration of the iris in the wound occasionally result and may require subsequent division.

_Acute glaucoma_ is by no means an infrequent complication--indeed the author has seen four successive cases of conical cornea, operated on both by excision and by the cautery, followed by this complication. It is probably due to adhesion of the root of the iris to the back of the cornea during the time the anterior chamber is empty. It can usually be relieved by an iridectomy.

=The electro-cautery operation.= The operation generally adopted is known as the target operation. It consists in surrounding the apex of the cone with two rings of cautery marks, the outer made at a dull red heat, the inner with the point slightly brighter, whilst the apex is cauterized at a red heat, so that rings of different depth are obtained. Cauterization of the apex should stop just short of perforation, the inner ring being deeper than the outer. With this method secondary glaucoma and anterior synechiæ are not so liable to occur. On the other hand, an optical iridectomy has to be performed more frequently. A few surgeons still cauterize the apex of the cone until a perforation is produced. This latter operation seems to have the disadvantages of both methods and the advantages of neither.

REMOVAL OF TUMOURS INVOLVING THE CORNEA

Tumours which involve the cornea are usually secondary to tumours occurring at the limbus. The chief of these are: _simple_--dermoid patches, moles of the limbus; _malignant_--sarcoma, endothelioma, epithelioma. Dermoid patches should be shaved off as close to the cornea as possible; the white area left after their removal can be improved by tattooing.

Malignant tumours in very early stages may be removed locally with scissors and forceps, the cautery being applied to their base, since they do not tend to invade the sclerotic deeply.

TATTOOING THE CORNEA

=Indications.= (i) To do away with the blinding effects of light through a scar after iridectomy has been performed (see p. 215).

(ii) To simulate a pupil on a white scarred cornea.

The operation is not without risks, as it may light up old inflammation in a previously quiet eye. Panophthalmitis and sympathetic ophthalmia have both been known to follow it. The pricking of the needle may carry in epithelium and implantation dermoids may arise.

=Instruments.= A fine single needle is generally used, occasionally a bundle of needles (Fig. 128).

=Operation.= Under cocaine. Chinese ink, sterilized and prepared by rubbing up with 1-6,000 perchloride of mercury, is smeared over the area to be tattooed. Multiple punctures in an oblique direction are then made into the cornea over the area desired. More paste is then rubbed in over this area. The cornea should be intensely black after the operation, as a certain amount of the ink is carried away by phagocytosis and shedding of the epithelium. Subsequent reaction may be reduced by means of an iced compress. Atropine should be instilled.

SCRAPING CALCAREOUS FILMS

Calcareous films, when not associated with active irido-cyclitis, may be removed with advantage to the vision. Care should be taken to see that no keratitis punctata is present before the operation is undertaken.

=Instruments.= Speculum, fixation forceps, a spoon which should have rather a blunt edge.

=Operation.= Under cocaine. The area is very lightly scraped with the spoon. The calcareous changes are in the deeper layers of the epithelium and Bowman’s membrane and hence are easily removed. The scraping should be carried well beyond the apparent margin of the film. The epithelium often takes some time to regenerate. As a rule the results are satisfactory, although the film is apt to recur in the course of years, but it may be removed again if necessary.

OPERATIONS UPON THE CONJUNCTIVA

THE REMOVAL OF FOREIGN BODIES

Foreign bodies lodged in the conjunctival sac, unless embedded in the conjunctiva, are usually found by the surgeon under the upper lid, the sulcus subtarsalis being a favourite situation. They are easily removed with a spud or needle, after the instillation of a drop of 4% cocaine solution. Subsequently the eye should be bandaged for a few hours until the effect of the cocaine has passed off, as in wiping the eye the patient may wipe off the epithelium of the cornea whilst it is insensitive from the cocaine.

_In order to evert the upper lid_ the patient is made to look strongly down, the eyelashes are seized between the thumb and forefinger of the left hand, the skin of the upper lid is pushed down above the tarsal cartilage with the thumb of the right hand, and the lid is everted by pulling it upwards against the point of the thumb.

OPERATION FOR PTERYGIUM

=Indications.= Pterygium should be removed when advancing across the cornea, especially when the pupillary area is becoming involved. The operation of ablation is the one now generally in use.

=Instruments.= Speculum, straight iris forceps, small sharp-pointed scissors.

=Operation.= Under adrenalin and cocaine the neck of the pterygium is seized with the forceps and the body and neck are carefully dissected from the conjunctiva. The body and neck should be very carefully separated right up to the corneal margin by means of forceps and scissors. The head is then stripped off the cornea with a sharp pull. The wound in the conjunctiva should be subsequently closed with fine sutures, otherwise the disease will certainly recur. In stripping the head from the cornea some of the epithelium may be torn off with it. This usually regenerates without impairing the vision.

EXPRESSION

This is an operation for the removal of follicular formations in the conjunctiva, and is used more especially in trachoma.

=Instruments.= Graddy’s forceps (Fig. 129), fixation forceps.

=Operation.= The operation may be performed under cocaine and adrenalin, a little solid cocaine being rubbed into the area to be expressed. In severe cases in which both eyes are affected, and in small children, a general anæsthetic may be necessary.

Although a number of instruments are in use, perhaps the best, and certainly the least painful, is Graddy’s forceps. In the case of the upper lid it is everted, one blade of the forceps being passed into the fornix, the other being placed over the upper surface of the everted