Operating on an eye

Unless you have received special training, limit your surgery to operations on a patient's lids: entropion (24.13), tarsal cysts (chalazion, 24.12), tarsorrhaphy (30.3), and evisceration, enucleation, and perhaps exenteration of his eye (24.14).

Trauma is described in Chapter 60. Although Section 60.4 describes the repair of a perforating injury, this needs good magnification, 8/0 or 9/0 sutures, and skill. So you would probably be wise to treat him non-operatively, and to give him subconjunctival gentamicin and atropine eye ointment.

EYE OPERATIONS EQUIPMENT. Don't operate with the large instruments of a basic set. Use the fine eye ones in Section 24.1. For operations on a patient's globe, an operating loupe and a bright focal beam are almost essential, preferably a 12 volt spotlight from a battery, or a transformer from the mains. A spirit lamp.

5/0 and 8/0 polyglycolic acid, silk, or monofilament sutures, all on 7.5 mm curved atraumatic needles. Monofilament sutures are better than silk on the cornea. 8/0 sutures are the finest ones that you can use without a microscope. Use virgin silk or nylon for the cornea, and catgut or polyglycolic acid for the conjunctiva. Nylon irritates if it is exposed.

PREPARATION. Prepare his face from his hairline to his chin and from ear to ear, using povidine-iodine 10%, or a non- alcoholic lotion which will not harm his eyes, if it enters them accidentally. Other surgeons use iodine and spirit, and take care to keep them out of his eyes.

Make a special drape with a slit from the middle of one end to the centre. Place this under his chin, and up each side of his face. Fold it over his head and keep it there with a towel clip. Place another drape across his forehead over his eyebrows, and clip this to the first one. If he is intubated, place a third drape over his nose and the catheter mount. If he is having a local anaesthetic, don't cover his nose or mouth.

ANAESTHESIA. You can usually use local (A 6.5) or general anaesthesia (A 16.9). Use general anaesthesia for a perforation (if local anaesthesia is complicated by retrobulbar haemorrhage, it may aggravate loss of eye contents).

POSITION the table so that you can sit comfortably, with your knees under it. If necessary, put his head at the foot end, or rest it on a plank, or sheet of wood, pushed under the mattress, and projecting beyond the table.

Sit your assistant on your right for a right eye, and on your left for a left eye. Keep your own eyes on the wound; ask him to place the instruments in your outstretched hand, and to hold them by their proximal ends, without touchng their tips.

You can use a speculum, or lid sutures, to hold an eye open while you operate on it.

TO INSERT A SPECULUM, on a conscious patient instil two drops of local anaesthetic. Ask him to look down, grasp his top lid with your finger, and slip the top blade of the speculum under it. Then ask him to look up, grasp his bottom lid, and slip the lower blade of the speculum under that. Adjust the arm of the speculum until his eye is exposed, and then tighten the locking nut.

LID SUTURES are not for suturing wounds, but to hold the lids away from an eye while you operate on it. They avoid the risk of a speculum, which may press on his eye, and perhaps scratch his cornea.

In his upper lid insert two 3/0 silk or monofilament sutures, just above his lash line and down to his tarsal plate. In his lower lid insert one suture just below his lash line. Don't penetrate the conjunctiva of either lid. Hold these sutures with haemostats.

BLEEDING. The cornea is avascular and cannot bleed. If his conjunctiva or sclera bleed, apply a pad and very gentle pressure. Or flood the wound with saline from a syringe and an irrigating needle, or an undine attached to a tube and silver cannula. The blood will stream in the clear saline, so that you can see the exact point where it is coming from, and control it with a cautery. Heat a squint hook or a small cautery in the flame of a spirit lamp, until it is hot, but not red hot. Touch the bleeding point with this, through the stream of saline. This will cool its tip enough to prevent burning, but will leave it hot enough to seal the bleeding vessel. Don't use diathermy.