Page:The American Cyclopædia (1879) Volume IV.djvu/110

 102 CATARACT healthy person, three images of it may be seen : the first erect, moving upward when the can- dle is moved upward, produced by reflection from the cornea ; the second also erect, pro- duced by reflection from the anterior surface of the crystalline capsule, and moving upward with the candle ; the third very small and in- verted, reflected from the posterior surface of the capsule, moving downward when the light is carried upward. In cataract, the inverted image is from the beginning indistinct, and soon disappears entirely ; the deep, erect one is also soon rendered invisible. By dilating the pupil with belladonna, this experiment is rendered easy and striking. Cataract is for the most part remediable only by a surgical operation; certain forms, caused by inflamma- tion of the capsule, may disappear with the exciting cause without an operation ; and cases are on record of the spontaneous cure of len- ticular cataract by the rupture of the capsule and the escape of the lens into the anterior chamber of the eye, where it is gradually dis- solved. From the earliest antiquity surgeons have attempted to destroy cataract by means of needles and knives of various forms. When- ever the disease is confined to the lens and its capsule, and the eye in other respects is healthy, and the patient not too young or too old, an operation may be attempted with a prospect of success ; in infants, and in persons under 20 years of age, both eyes may be ope- rated on at once; after the age of 80, the chance of a successful issue is generally small. Before submitting persons to this operation, it is well to prepare them a day before by a mild diet and a gentle laxative, and to allay any inflammatory tendency of the organ ; and then to smear belladonna ointment around the orbit, or to put a few drops of its fluid extract into the eye, for the purpose of dilating the pupil to its utmost extent. All operations for cataract reduce themselves to three, which have for their object either to displace the lens, to break it up, or to remove it from the eye. 1. Operation for depression of the lens, or couch- ing. The description of this may be found even as far back as Cclsus ; it has undergone many modifications in modern times. The in- strument employed is ^ fine needle, either slightly curved at the end" or straight with the point spear-shaped ; Scarpa>'s needle is slightly curved at the end. When th needle is passed through the sclerotic, as ordinarily, the opera- tion is called scleroticonyxis ; when it is passed through the cornea, Keratonyxis. Different needles are preferred by different operators ; but, as in the case of the stethoscope, that in- strument is the best to which the surgeon is accustomed. In scleroticonyxu the needle, held like a pen, is passed through the sclerotic perpendicularly to its surface, a line or two from the cornea and a little below its trans- verse diameter ; the concavity of the instrument is turned down, in order to separate rather than to divide the fibres of the membrane ; when the needle is fairly in, its concavity is turned back- ward, so that it may pass under and before the lens without touching the iris or the capsule ; when it has reached as far as the pupil, the cap- sule is lacerated by delicate circular movements of the point ; then the needle is applied direct- ly to the lens, which is pushed outward and backward to the bottom of the globe, out of the line of the axis of vision ; it is held there a short time, that the cells of the vitreous hu- mor, into which it is pushed, may resume their position around it, and thus prevent its reas- cension in the line of the pupil. Some surgeons prefer the operation by reclination, which con- sists in turning the lens backward from an upright to a horizontal position ; and some always recline the lens before they depress it. In keratonyxw, the needle is passed through the cornea, about an eighth of an inch from the sclerotic, on its lower and exterior portion, and is directed through the dilated pupil to the lens, whose capsule it is made to lacerate ; and, if possible, the lens is depressed, reclined, or broken up. This method is objectionable on account of the danger of wounding the iris, and of the difficulty of reaching the lens, and is applicable only to exceptional cases. After the operation, the eye should be lightly covered, and the patient should remain in bed in a dark- ened room, with the head raised, and be kept on a low diet for a few days ; after four or five days in ordinary cases, a little light may be gradually let into the room, and at the end of three weeks the eye may be generally left un- covered. The accidents most to be feared are in- flammation of the iris, choroid coat, and retina, which should be treated by antiphlogistic mea- sures. 2. The operation for breaking up the lens, without depressing it, is very easily performed, and excites very little inflammation ; but it re- quires frequent repetition, is slow in its progress, and is adapted only to soft and especially to con- genital cataracts. The needle is inserted just as in the method for depression, the capsule is di- vided, and the lens is freely broken up without removing it from its place ; the cataract is thus brought into contact with the aqueous humor, and is gradually dissolved by it. 3. In the operation for extraction, the cornea is incised through rather more than half its circumference, the capsule is lacerated, and the lens is extract- ed from the eye entire ; it is performed with a triangular knife, with sharp point, straight and blunt back, the edge slanting obliquely, and the blade growing wider and thicker as it approaches the handle ; this kind of knife cuts by the simple motion of pushing, and fills up the incision as it makes it, thereby preventing the escape of the aqueous humor. The cornea may be cut on its inferior or superior half, or obliquely on its ex- ternal and lower portion, each of which has its special advocates. When the lower half is cut, the knife, with its edge downward and forward, is passed into the external side of the cornea, perpendicular to its axis, a little above its trans- verse diameter, and about a line from the scle-