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Show 38 or coucmxe, on Dnrnnssme THE CATABACT. in all probability, the cataract has not escaped from its cap. sule, and, on withdrawing the needle, it will rise again. He therefore would have to blame himself, if, having with- : . ",'-‘ tiously withdraw the needle from its hold upon the cataract, but not altogether upon the eye; then, if the cataract does not appear in the pupil, the needle is to be slowly with- .,--_-->1..-n5«w. «any..- .a ".4. ::r: ,. .r ration would be still to do. When, perhaps after repeated efforts, he has sunk the cataract out of sight, he must cau- "a. drawn the needle from the eye, he saw the cataract again forced up, and take its place behind the pupil, for the ope- '43de mom drawn. The fact is, that when the needle has carried down the cataract, the cataract is not yet unseated from its capsule, and instead of being separated from the vitreous humour that body has revolved with; by the elasticity of the membrane it will resume its former relation, and of course carry up the cataract, so as again to present it in the axis of the eye. But the cataract may have been separated from its connexions to the fore part of the vitreous humour, and yet rise in a partial manner, on withdrawing the needle ; this is, i2 5. 5 ,, :-I ‘2‘ r}, \I. because it had not been so forced into the vitreous humour, as to break on its capsule, and make a lodgment for itself; the elasticity of the vitreous humour throws it out again. It is incorrect to say, that the cataract has been buoyed up, since it is specifically heavier than the vitreous humour. There is a possibility, that the cataract may escape from under the pressure of the needle, and pass through the pu~ pil, into the anterior chamber of the aqueous humour. If the whole or part of the cataract escape thus, we ought to let it remain; it will dissolve in the aqueous humour, and be finally absorbed. The cataract may start backwards, too, so as to be deeply immersed in the vitreous humour. I have seen it faintly shining half an inch behind the pupil. I fancy this is not a frequent accident; if it should happen, we are to do no Violence in endeavouring to remove it, as we are assured it will dissolve, since it must, in this case, be freed of its capsule. OF COUCHING, OR DEPRESSXNG '1'le CATARACT. 39 10. It is a more difficult thing to fulfil the intention of the operation, when the cataract is soft or cheesy, for when the needle is pressed upon the cataract, the needle passes through, without dislodging it from its place, nor does the matter flow out from the capsule. We ought, in this case, to break, or burst through the capsule, and, as freely as possible, admit the aqueous hu. mour through the anterior part of the capsule; and a second intention ought to be to break down the cataract, which is increasing the chance of its dissolution afterwards. By perseverance in pressing with the broad edge of the needle, without injury to the eye, it will often be possible to remove the cheesy matter from the centre of the pupil, so that afterwards the patient shall see a little. 11. If there be an adhesion of the cataract to the iris, we shall discover this by the irregular figure which the pupil assumes upon the variations of light, admitted to the eye. During operation, if the depression of the cataract should disorder the regular circle of the pupil, it is owing to an adhesion, and we must endeavour to separate the cataract, and iris, by the edge of the needle, before we attempt finally to depress the cataract. 12. If after a few days the eyelids are opened, and there appear any fragments of the cataract, they are again to be depressed, or pushed before the pupil by the needle; but this is not to be done until the inflammation and irritability, the consequence of the first operation, have entirely sub~ sided. 13. The remains of opacity behind the pupil, may be what is termed the membraneous cataract. To tear away these shreds, and to push them below the level of the pupil, or through the pupil into the anterior chamber of the aqueous humour, a needle should be used so curved near the point, that by merely rolling the needle, betwixt the finger and thumb, the point of the needle may be moved pretty exten~ Sivrly‘ With such a needle the operation may be done with ivss violence, and a smarter motion may be given to the point HIM. WflPFh o:- |