Operations upon the eye differ so widely from general surgical operations that it is necessary to say something of the preparations for them before passing 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 anæsthesia; 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, screwing 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 associated 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. _Anæsthetics._ _General_ anæsthesia 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 anæsthetist should stand on the side away from the eye being operated on. The local use of cocaine in addition to general anæsthesia is indicated when operating on patients to whom it is advisable to give as little anæsthetic as possible. [Illustration: 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.]