CATARACT (Fr. cataracts, Lat. cataracts, from Gk. KaraNuikrsc, katarrhaktes, waterfall, from sara, kata, down -I-- rlu'gnynai, to break; or less probably from eimiaaciv,arasscin, to dash in pieces). An opaque condition of the lens of the eye or of its capsule. It is readily distinguished from opacities of the cornea, or clear front part of the eye, by its position just behind the pupil—that round and varying aper ture in the iris through which light is admitted into the back of the eye. Cataract is called primary when independent of other disease of the eye, and secondary, or complicated, when the reverse is true. The opacity of the capsule of the lens or of the lens itself, following operations for cataract, is known as secondary cataract or after-cataract. Cataract may effect the lens alone (lenticular cataract), or the front or back of the capsule of the lens (capsular cata ract), or both lens and capsule (capsulo-lenticu la• cataract). A cataract is called partial when limited to a portion of the lens; complete when involving the whole; stationary if it remains partial; progressire if it tends to include the (Mire lens. The last is either senile, congeni tal, jurenile, or traumatic. In patients under thirty-five years of age cataracts are soft and white, and are called soft cataracts. In older persons the nucleus is hard and yellowish, and then the term hard cataract is applied. The whiteness of a cataract may vary from the color of half-boiled white of egg to that of snow. Beat will produce a like change on the lens removed from the body, just as it changes white of egg from transparent to opaque. The round lens of the fish is seen at table in this opaque condi tion.
Cataract is painless and unaccompanied by inflammation. It occasions blindness simply by obstructing the passage of the light ; but rata Fact alone does not produce so complete blind ness but that the patient can tell light from darkness. The eatoptrie test, now disused. was an ingenious method of distinguishing incipient cataract from certain other deep affections of the eye. When a lighted candle is held before the eye of a person whose back is to the window, three candles are seen in the healthy eye. Two are erect—the large front one caused Icy the convex cornea, the smaller and fainter one be hind by the convex front of the lens. The third, occasioned Icy the concave back of the lens, is in the middle; it is small, bright, and is upside clown; when the candle is moved it goes in the opposite direction, while the two erect images move with the candle. When the back of the lens becomes opaque, the inverted image is ob scured or disappears. and when the front of the lens is affected only the great front image, caused by the cornea, remains. At the present
time cataract is accurately detected by con centrating light upon the eye and illuminating its interior by means of the ophthalmoscopic mirror, the eye being previously dilated by some mydriatie, such as atropine or homatropine. No difficulty then arises in determining at once the nature of the disease.
No medical or other treatment has any in fluence in arresting the progress of cataract, nor can it be cured except by surgical operation. A clever imposture used to be practiced by quacks. By applying belladonna to the eye— as the surgeon does when he wishes to dilate the pupil for an examination or operation—some little light was temporarily admitted through the less opaque edge of the lens. The patient, beginning to see somewhat better, after long and increasing dimness of vision, began to con gratulate himself on a cure. The quack. of course, hastened to get his money without wait ing for the further result, which was sure to be blank disappointment.
Traumatic cataract results from a perforat ing wound of the capsule of the lens. The en tire lens becomes opaque, and a portion of it usually remains so; but at times, unless intlam illation of other portions follows, the cloudiness entirely disappears. Congenital cataract is due to imperfect development or intra-uterine in flammation. Juvenile cataract may be heredi tary. or its cause unknown. In both congenital and juvenile cataract the lens is soft and white. They are treated Icy 'needling,' an operation in \ ich a needle-like knife is employed to cut and break up the lens at several operations. The injured lens is then absorbed. Senile cataract, the most important form. usually occurs in per sons over fifty, and generally involves both eyes. Its period of development may Ice a few months or many years. Beginning in the forin of gray streaks extending from the periphery toward the centre of the lens, or as spots in any por tion, it may eventually render the entire lens opaque. As the fluid of the lens is then ab sorb•d, it becomes easily separated from its capsule, and is knoN(n as ripe for operation. If neglected, other changes may take place, mak ing the results of operation poorer, from opacity of the capsule, etc. The only method of reliev ing senile cataract is extraction of the lens, with or without excision of a portion of the iris. The -ornea is opened along a little less than half its circumference, the capsule of the lens is cut, and the lens is expelled Icy gentle pressure.
Great care must he used in the dressing and later treatment to avoid accidents. re moval of the cataract, the natural lens being absent, its place must be supplied Icy strong