Elements of Surgery

by Robert Liston

Of Cataract, or opacity of the crystalline lens and its capsule, attended with partial loss of vision.—The disease is, in general, gradual in its progress: but sometimes it advances rapidly, as when occasioned by a blow or wound. When slow, the opacity commences in the centre of the lens, and extends gradually towards the circumference. Before any change can be perceived in the organ, the patient sees objects as if covered with a mist or veil; and, as the opacity becomes distinct, vision is gradually impaired. During the day, vision is very indistinct, as the pupil is contracted, and the rays of light reach the retina only through the opaque centre of the cataract. But during twilight vision improves, as then the pupil becomes dilated, and admits of transmission of light through a portion of the transparent vitreous humour, as well as through the semi-opaque margins of the crystalline lens: for a similar reason, it is also more distinct after the application of belladonna or hyoscyamus either to the eye or to its neighbourhood. In the ordinary state of the parts, a clear black ring is often visible around the opacity, either from the margins of the lens being unaffected, or from the posterior surface of the pupillary portion of the iris being pushed forwards by enlargement of the lens. Patients, having become aware of the great improvement of vision caused by dilatation of the pupil, are often contented to use narcotic remedies externally, so long as they retain their dilating influence—and, strange to say, they do not soon lose it—instead of submitting to any operation. As cataract advances, even luminous bodies cannot be accurately distinguished, though the situation from which the light proceeds is perceived; thus the patient in a clear light may have an indistinct perception of a candle or window, and in some cases even of the bars of the window. The motions of the iris are not affected, unless, in rare cases, when the cataract is large and compresses the iris; or when the functions of the third pair of nerves have been in any way impaired; or when the iris has been the seat of acute inflammation.

Cataract may be confounded with other diseases of the eye, as with amaurosis. But, in amaurosis, opacity, when it exists, is deep, concave, greenish, or of a metallic appearance; whereas, in cataract, it is of a more or less white colour, convex, and situated immediately behind the pupil.

Cataract may be lenticular only, the lens being opaque whilst its capsule remains transparent. In such a case the disease is slow in its progress, and the opacity uniformly commences in the centre of the lens, and gradually extends to the circumference. The degree of opacity varies in different cases, from cloudy dimness to complete whiteness. In general the predominant hue is white or greyish, but not unfrequently the opacity is of several colours, and occasionally of a mottled appearance. The consistence also of lenticular cataract varies, being sometimes fluid, occasionally extremely dense and almost osseous, but most frequently of caseous consistence. When fluid, the cataract is of larger size than the healthy lens; when caseous, the part usually retains its former dimensions; and when dense, the lens is often considerably diminished in size. The motions of the pupil are seldom, if ever, affected.

Cataract may be entirely capsular, the capsule being opaque, whilst the lens either remains free of disease, or has been removed by natural or artificial processes. The opacity in this case does not always commence in the centre, but frequently begins at the margin, and is of a spotted or mottled appearance, and in general not uniformly opaque. No black ring around the opacity is observed, though the pupil be dilated; and the motions of the iris are sometimes slow. The opaque spots are said sometimes to move when the position of the head is changed. The anterior portion of the capsule, the posterior, or the whole, may be affected; but the anterior is the part which most commonly becomes opaque in the first instance.

In many cases both lens and capsule are affected; and then the cataract is termed capsulo-lenticular. Occasionally the diseased lens, in such circumstances, is of fluid consistence; and in many cases is spotted.

Portions of lymph, organised or not, lodged in the posterior chamber, have by some been termed spurious or adventitious cataract; since, when the pupil is shut by such effusion, the appearances presented are somewhat similar to those caused by opacity of the lens, or of its capsule. Such deposits, however, can readily be distinguished from true cataract, being in general of a yellowish colour, in close contact with the posterior surface of the iris, and, when organised, often streaked with red vessels. Generally, too, the pupil is irregular from adhesions between the lymph and the pupillary margin of the iris.

Cataract would, in some cases, appear to be hereditary,[27] and frequently it is a congenital affection. In very young children it may be caused by imprudent exposure to strong light. In adults it often seems to be produced by the action of strong reflected light, as by exposure to intense fires in forges, glasshouses, &c., or by a dependent position of the head, accompanied with exposure to light. People advanced in life are most subject to the disease.[29] It is not an unfrequent consequence of internal ophthalmia, and almost invariably follows the slightest wound or most delicate puncture of the lens: it often occurs after slight injury of the lens or its capsule, inflicted during attempts to form an artificial pupil. Cataract may occur rapidly from extensive dilatation of the lenticular vessels; or from such an injury of the eye as causes laceration of the vessels supplying the capsule and lens, detaches them from their other connexions, and consequently leaves them without a nutritive source.

Cataract sometimes, though rarely, disappears spontaneously, being absorbed; but most frequently an operation is required to remove the opaque body from the axis of vision, though no hurry is necessary in having recourse to it. The chance of success from operation must depend very much on the state of the different parts of the eye, on the kind of cataract, and on the state of the constitution. Many remedies, external and internal, and mercury amongst the rest, have been employed with the view of dissipating cataracts; but all are of no use. An operation, of one kind or another, only can be relied on. And still, even in favourable cases, and in the best hands, the contingencies attending operation are so great, that success cannot be absolutely promised or expected. The mode of operating, and the kind of operation, must be varied according to circumstances; and great experience is required to determine the proper course of procedure in each case. Steadiness is absolutely necessary both in the patient and the operator, in order that the proceedings may be carried to a happy conclusion. The operator must have a good eye; a steady, light, and skilful hand; a fine touch; courage and caution—qualifications necessary in all surgical operations, and in none more so than in those on the eye.

When cataract is spontaneous, and vision not altogether lost, the patient being able to distinguish bright objects, though unable to direct his steps or follow his avocation—when the pupil is quite sensible to the application or abstraction of light, or to the use of belladonna, &c.,—when all the external parts are sound, the cornea clear, the chambers of the proper size, and no reason to suspect that the retina is affected—the prognosis in regard to the effects of operation is good. When, on the contrary, the organ or the constitution is not sound—when the patient is irritable in habit or temper, or subject to gouty, rheumatic, or catarrhal complaints—when headache has preceded the opacity, and vision is gone, or nearly so, with flashes of light seeming to pass before the eyes—the prognosis is very unfavourable. But even total blindness must not always be considered as an indication of operation proving useless, for sometimes the retina recovers its sensibility after removal of the cataract, and thus sight has been restored in very hopeless cases. There is no objection against operating, though one eye only is affected. By some, operation is recommended as prudent, with a view of preventing the opposite eye from suffering by sympathy; whilst others consider it more safe to refrain from operating, lest violent inflammatory action should follow, and, by extending to the other eye, cause disease there. However, when the cataractous eye does not present such appearances as forbid operation, I conceive it both prudent and safe to remove the obstruction to vision, provided after-treatment is carefully attended to, and all untoward symptoms actively combated as soon as they appear. There is still a considerable difference of opinion on the subject; but the patient, being anxious to get rid of an inconvenience and deformity, often decides for the surgeon. When both eyes are cataractous, a question arises as to operating on both eyes at once. From my own experience I should say, that both eyes ought not to be operated on at one time: if they are, there is great risk of violent inflammation being established, and of the operation failing to restore vision. Immediately after one eye has been operated on, the other becomes very unsteady, and is altogether in an unfavourable state for operation; and, if interfered with, the chance of a happy result is but slight. But by operating on each eye at different times, much less risk is incurred, and the chance of success is doubled.[30] Cataract may be operated upon at all ages, excepting infancy and the period of dentition. In congenital cataract, the eyes acquire an uncontrollable rolling motion, and, if operation be delayed till the patient has attained a considerable age, such motion cannot be afterwards prevented. In such cases, therefore, the disease should be attacked as soon as dentition is completed, for then an operation can be undertaken with as little risk of injury to the organ as at a more advanced age; and a child of twenty months or two years is unconscious of what is intended, and can be more readily secured than at any after period; besides the best period for education is lost if an operation be not done early.[31]

Cataract is not remediable but by surgical operation. It may be removed altogether by incision of the tunics of the eye, and extraction of the opaque body; or by the introduction of a needle, it may be displaced from the axis of vision, or so disturbed as to be acted on and removed by the absorbents.