OCR Text |
Show 36 or coucumc, on DEPRESSING TIIE CATARACI‘. .rvr-r) .n-bu-Ipra'h-uwy ~..t¢ .. a, .. . , "up-1y... £4.47)? -_.4-_ . .w._.7,. gers at the same time on the margin of the orbit, so that what firstly mum ' \ pressure they give to the eye may be steady. 3. The surgeon sitting down before the patient, places his foot upon a stool of such a height, that when the elbow rests on the knee, the hand may be opposite the eye. Now with the fingers of one hand, he presses down the lower eyelid, and when he wishes to fix the eye, as he is about to introduce his needle, he pushes upon the eyeball with the point of his fingers. It is to be particularly observed, that any change of the de» gree of pressure on the eyeball during the operation, is to be made by the motion of the operator's fingers, the assistant has only to keep steady. 4a. The surgeon having dipt his needle in oil, he takes it as he would a writing pen, he rests his little finger on the bone of the cheek, and he pierces the white part of the eye, in the middle betwixt the margin of the cornea, and the angle formed by the eyelids, the patient's eye being directed straight forwards. The needle should pierce the sclerotica in a direction perpendicular to the convexity of the surface, or, in other or coecnmo, on Deranssmo THE CATARACT. braneous cataract. 37 We have, therefore, to push the needle in a direction parallel to the iris, and get before the lens, then carry the point through the pupil, so as to burst through, or cut the fore part of the capsule. 7. Supposing that on the first touching the capsule of the lens, a white fluid escapes, and makes the aqueous humour turbid, we are not on this account to despair of success ; for this milky and dissolved state of the cataract promises a quick absorption, and restoration of vision. It is our busi. ness in this case to tear the anterior half of the capsule, as wider as we may, without hurting the iris, and to plunge the needle repeatedly into the cataract, and then to tie up the patient's eye as usual. 8. Having torn the capsule, the surgeon withdraws the needle a little, and puts it over the cataract, or pierces the cataract high on its disk. Now the point of the needle is to be depressed, by raising the handle of the instrument; but at the same time that the point of the needle is depressed, (carrying the cataract with it), it must be moved backward, words, pointing to the centre of the eye. I n 5. The needle is now to be somewhat changed in its direc- tion, and carried horizontally until the point appears behind the pupil, for it is to be observed that, although the opacity of the lens is considerable, yet the needle is seen through it, or when it is immersed in its substance. The flat surface of the point ought to be towards the iris, as the sharp edge might fawn" ":1. "thin-‘5‘ _-..,--‘,,,‘."l "a. < , . , cut the iris. .. . 6. The first motions of the needle, I conceive, ought to be calculated to pierce and tear the anterior part of the capsule of the lens. And this for two reasons. Before the cataract can be displaced from its seat in front of the vitreous humour, its capsule must be broken, and this being done, by piercing it on the fore part, of course facilitates the descent of the cata ract. Again, without this precaution, it happens that the cataract being couched, the fore part of the capsule remains, and in the inflammation which necessarily follows the opera tion, it becomes opaque, and forms what is called the meme For example A, being the lens in its natural situation, to remove it from the axis of the eye, or course of the rays of light B, C, it is not to be pressed directly downward in the line D, but in the circular line E, which answers to the con~ cavity of the coats, and by this movement it will be carried down and lodged at F. 9. When by raising the handle of the needle, the operator has carried the opaque cataract thus below the level of the pupil, and the pupil is clear, the operation is not done, for |