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Show 0F COUCIUNG, OR DEPRESSING TEE CATARACT. 3:} ugfiffla-xfl Ana-a "a. >w ..»_ OF THE CATARAC'l . t? i f t l i g The following circumstances previous to the operation, have to be attended to. 1. Is the patient though blind, still sensible of the variations of light, does he distinguish when an opaque body is passed before his eyes, or can he distinguish light from darkness? The reason of attending to this circum~ stance is, that we may discover if the retina be yet sensible, though the rays of light are with difficulty transmitted, through the opaque crystalline humour. 2. Is the iris still Droveable ? because if it still enjoys its motion, light being it: only stimulus, and the retina being alone sensible to light, it indicates the sensibility of the nerve. 3. Further in the mo. tions of the iris, we have to observe if the pupil remain perfectly regular. The irregularity of the pupil, may, most probably, be owing to some adhesion of the cataract, to the edge Surgeons of eminence, and oculists, still dispute this pOint, eiz. whether the depression or extraction of the cataract, be the preferable operation. The depression of the cataract is done by introducing a needle into the eye, and removing the. opaque lens from the axis of the eye. The extraction is a very improper term, but it means the making an incision into the cornea, by which the cataract escapes, being pressed for« ward by the vitreous humour. In the performance of these operations, the utmost delicacy is required, and they have a result the most interesting of any of the operations of surgery. Although the general opinion, at present, be in favour of the operation of couching or depressing the cataract, yet all I have seen makes me prefer the operation of extraction. I shall, however, describe the operation of couching the cataract, first. of the iris, and indicates to us, that there has been a deep i11- IIlsSaw '1 mom I w" fiammation there. The irregularity of the pupil, is an unfa~ vourable circumstance, but not a total bar to the operation. 4. The cataract which has arisen from a blow on the eye, or after violent and deep ophthalmia, is, for the same reason, unfavourable. Since it is reasonable to suppose, that thr- r "WW" 'Ijv awn-"iv".‘w f.~".s.\« .9 ,w . F l t .--;r;v_-;..~,:::-:-z '. «gm-'3" firm, '42" membrane of the lens has been thickened, and has formed a firm adhesion to the surrounding parts. But fortunately the cataract is not often preceded by this inflammation. 5. When we look into the eye, to discover the seat of opaci ly. We look first nearly perpendicularly into the pupil, but. then we must turn the patient's head gradually until we see the profile of the cornea; and now if the opacity should be caused by an effusion in the back part of the cornea, it is dis‘ tinctly seen to be before the iris. G. The deep black transparency of the pupil, and the want of motion in the iris, will sufficiently distinguish the amaurO- sis (the insensible state of the retina) from the cataract. 7. The cataract maybe of a consistence firmer than the lens is naturally; it may be soft as cheese; it may nor/1i» quid like milk, when punctured, but I know not how to fore» see these distinctions by attending to the appearance of the cataract. before operation. 0F CO‘UCHISG, OR DEPRESSINC THE CATARACT. THE operation should not be performed on one eye, while the other is sound; and when both eyes have cataracts. though we have great temptation to operate on both, (by which on the whoic we increase the chance of success) yet I conceive the operation should be done on one side only at a. time. If the eyelids be much affected with a chronic inflammation, we ought to endeavour to correct this, previous to the operation. But if this is obstinate and habitual, and to no great extent, it makes no objection to the operation. N0 cross light must be admitted into the room; the north light is to be preferred, and it should strike obliquely on the eye. 1. The patient is seated on a chair, with a long upright back. A pillow is placed to receive his head; the assistant stands behind him to press his head upon the pillow, and in part to support it with his breast. A napkin is thrown over the other eye. 2. The assistant puts the points of his fore and middle fin« ger, on the upper eyelid, and raises the eyelid, at the same time he gives a slight pressure to the eyeball, but rests his finw |
