A Manual of the Operations of Surgery, Joseph Bell [suggested reading .txt] 📗

Extraction of Soft Cataract by Suction.—Mr. T. P. Teale, of Leeds,[87] has invented an instrument by which the removal of soft cataract is made more easy, through a linear incision by suction, applied through the medium of a hollow curette furnished with an india-rubber tube and mouth-piece.

The curette is of the usual size, but is roofed in (instead of being merely grooved) to within one line of its extremity, thus forming a tube flattened above, but terminating in a small cup. This is screwed into an ordinary straight handle, which is hollow for a short distance, far enough to join with a second tube fixed at right angles to the handle, and into which the india-rubber pipe and mouth-piece, through which suction is to be made, is attached. In many cases it seems to serve its purpose extremely well.

Certain points require attention:—1. That the puncture to admit the curette is large enough; 2. That its end be sufficiently rounded; 3. Its open end must be held in the area of the pupil, and not allowed to pass behind the iris, else there is great risk of the iris being drawn in. Among other advantages claimed by its inventor, the chief seems to be a more thorough removal of the lens than by the ordinary means, and consequently less risk of opaque deposit in the posterior capsule.

(2.) Extraction by Flap.—When properly performed in a suitable subject, and when free from accident, this operation is one of the most thoroughly beautiful and satisfactory in the whole domain of surgery; but it is difficult, and liable to many risks which neither skill nor caution can completely guard against.

It is required in many cases of hard cataract, which are amenable neither to solution nor linear extraction.

Operation must be considered in various stages:—

a. To make a flap of cornea large enough to permit of the removal of the entire lens without pressure or bruising. To make it of cornea only, to prevent the escape of the vitreous, and to avoid injury of the iris.

The great difficulty in making the required section of the cornea is, that we are debarred from using scissors or any ordinary knife or scalpel in making it, for this reason, that the sawing movements required in all ordinary cutting are inadmissible here, as any withdrawal of the blade, however slight, would permit evacuation of the aqueous humour, and at once be followed by prolapse of the iris before the knife. Hence we are compelled to make the requisite flap by one steady push of a knife, which, too, must be of such a shape as in its entrance constantly to fill up the wound it makes. Very various shapes and sizes of knives have been proposed, the one called Beer's knife being the sort of model or common parent from which all the others are derived. It is triangular in shape, with a straight back, about 12-10ths of an inch in length, and 4-10ths broad at the base of the blade, tapering at a straight edge from its base to its point, and also diminishing in thickness to the point.

Considerable difference of opinion exists as to the relative merits of an upper or lower section of the cornea. The general view at present seems to be that an upper section is to be preferred; but in cases where the surgeon is not ambidexterous, it is better that he should make the section which lies easiest to his hand than attempt an upper section in a less favourable position.

The patient should be placed flat on his back, the lids should be gently opened, the upper one by the surgeon, the lower one by his assistant, who is to press the lid downwards against the malar bone without exercising any pressure on the ball. The eye should be still further steadied by the conjunctiva and subjacent cellular tissue on the inner side being seized by a pair of catch-forceps, still with no downward pressure on the ball. The point of the knife must then be introduced about a line from the outer sclerotic margin of the transverse diameter of the cornea (Fig. xiii.), the blade being held parallel with the fibres of the iris, pushed steadily across the anterior chamber, and protruded as nearly as possible at the corresponding spot at the inner side of the cornea. The aqueous humour should not escape till the section is completed. If it does, the iris is almost certainly projected forwards and entangled in the blade of the knife, a most annoying accident, and one which is not easily remedied. The books tell us of various manœuvres by pressure or otherwise, by which the iris may be pushed back. Practically, however, if it has once occurred it is not easily saved from being cut. If a small portion only is involved, it is not of much consequence; if a large portion be in danger, it is sometimes necessary to withdraw the knife before the section is completed, and finish it with a probe-pointed, curved bistoury.

If, however, the flap is safely finished, the lids should be gently allowed to close for a few seconds.

On opening them again the surgeon must decide whether the corneal flap is sufficiently large to allow the lens to come out without force; if not, he must enlarge it either by the narrow probe-pointed "secondary knife" or by a pair of sharp scissors. Occasionally the lens, and even a little vitreous humour, may escape at once on the section being completed, but this is not to be desired.

b. Laceration of the Capsule of the Lens.—This is performed by insinuating a sharp curved needle under the corneal flap, avoiding the iris, and then tearing up the anterior capsule through the dilated pupil, the chief point to be attended to being that the capsule be lacerated in its entire length.

c. Removal of the Lens.—This must be done with the most extreme caution and gentleness, lest the vitreous humour be also evacuated. The surgeon's object is to tilt the lens so as to turn it slightly on its transverse axis, and cause the edge nearest the section to rise out of the capsule and appear at the wound. This is best done by gentle pressure at the required spot by the back of the needle, or by a common probe. When the lens begins to protrude the pressure must be very, gentle, lest it be forced out suddenly and the vitreous follow it.

Soft portions of the lens are apt to remain adherent to the wound in the cornea. These must be removed by scoop or probe.

Varieties in the method of Flap Extraction.—Jacobsen of Königsberg in every case gives chloroform. He always makes his flap in the boundary line of the cornea and the sclerotic, through a vascular structure, and he believes that union is on this account more rapid, and after extraction removes that portion of the iris which appears to have been most exposed to bruising during the exit of the lens.

The operation of extraction may in many cases be either preceded or followed by iridectomy, as proposed by Mooren, Von Graefe, and others. The following operation seems to diminish the risks to a very great extent:—