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Show or IKE EXTRACTION or THE CATARAC'I‘. it) _r-7vir)<~w‘--w;-_\$r3H-|w <--..,'.., ‘rr: . ,- <fr‘rs', (:4 xx}? . .3 .. m. of it, than where, in order to give motion to the point of the needle, we have to raise the handle. inc". , ,j4350w mom- 111‘. Any portion of the cataract, or any shreds of the cataract, or its capsule, which are accidentally pushed into the anterior chamber of the aqueous humour, are to be allow ed to remain there, for they will be dissolved, and carried away by absorption. 15. The secondary cataract is the opacity of the remaining capsule, which is not carried down with the opaque lens, but remains in its situation. The secondary cataract may be per- fect or partial. It may be said to be perfect when the lens has escaped from the back part of the capsule, and has been immersed in the vitreous humour, without the anterior half of the capsule being torn from its connexions to the ciliary process, or rent in any way. This is more apt to take place, than we at first would imagine likely, from the greater tenuity of that part of the capsule which is towards the vitreous huv mour, than the anterior portion of it. The imperfect, or partial secondary cataract, is the remaining shreds of the anterior part of the capsule. It is an opinion, that only the anterior part of the capsule is liable to become opaque, and 1 think this is very likely ; there is a foundation in anatomy for supposing that the anterior, and posterior part of the capsule of the lens, are of a different nature. guished in the living eye, (because the vitreous humour forces the back part of the capsule into contact with the iris, after the depression of the lens itself,) and happily it is of little con» sequence to know what part of the capsule is thus diseased, as this supposed distinction would make no variation in the practice. 16. In operating for the membraneous or secondary cataract, the intention with which we use the needle may be somewhat varied. l'Ve first endeavour to tear down the opaque membrane, and to place it under the level of the pupil, or we may attempt to gather the shreds of the membrane together, to loosen them from their natural attachment, and to push them through the pupil, into the anterior chamber of the aqueous humour where they will be dissolved and absorbed. We ought not to be too persevering in our attempts to clear the pupil of the membraneous cataract at once, on the contrary we should be careful to do little injury, so that we may avoid raising inflammation. "'0 repeat the attempt after a time. The needle should be very fine, and curved at the point, not like that which is adapted for pressing down the cataract of the body of the lens. OF THE EXTRACTION OF THE CATARACT. It is this conviction, that the fore part of the capsule is most frequently opaque, and that it is the most liable to be so after the operation, that induces us to be careful to pierce, and break down this fore part, before couching the opaque lens. If this has been done, only shreds of opaque membrane can be visible in the pupil, after the operation. And if they appear, wc ought to let them remain for some time, in the exruxmfy'hj- ~‘v~z,,;.«,- fa-Atckt. rash, . _. A ‘ . 4.1 or cocaine, on nernnssmc THE CATARACT. pectation of their wasting, and acquiring transparency again. I have seen, on dissection, an opaque spot on the back of the capsule, and therefore I am forced to say, that the secondary cataract. may be in the posterior segment of the capsule of the lens. But whether the opacity be in the back, or fore part of the capsule, is of little consequence, since it cannot be distin an. extraction of the cataract, I allow to be a more for- midable operation than couching ; but when it is well done, it is more uniformly successful. I do not know that it is more difficult to perform extraction, than it is to perform couching ; but the blunders in this operation are at once apparent, while in couching the errors are concealed; and even the initiated cannot precisely say from the motion of the hand, whether the operator be, with delicacy and niceness of intention, removing the opacity from the pupil, or making unmeaning, and consequently, unsuccessful motions of the needle. Freedom from tumefaction and inflammation of the eye- lids, and of all tendency to ulceration in their edges, or to opa"v",‘I. ll. f} ‘F*III \ u '9‘" z r]! r ' I |
