Glaucoma / by Priestley Smith.

  • Smith, Priestley.
Date:
[1891]
Catalogue details

Licence: Public Domain Mark

Credit: Glaucoma / by Priestley Smith. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    (passage for the fluid into Schlemm's canal, or the adjoining veins, j Whatever be the precise explanation of the permeability, the practical I fact remains that the more nearly the incision coincides with the j[ normal outlet — the angle of the anterior chamber — the more certain, cceteris paribus, is its efficacy; and this, be it observed, is no theoretical inference, for it was established long before the physiology of this region was understood. Mode of performing iridectomy for glaucoma,—It is desirable, in most cases, to employ an anaesthetic (pp. 401-6). I have a strong preference for ether, on account of its superior safety. I also habitually administer a draught containing fifteen or twenty grains of chloral, from twenty to thirty minutes previously (p. 403). The operator stands or sits behind the patient's head (p. 400). The patient being anaesthetized to complete muscular relaxation, the eyelids are separated with a stop-speculum, the conjunctiva is seized with toothed forceps near to the lower corneal margin, and the eye is rotated downwards, if necessary, so as to render the upper portion of the ciliary region easily accessible. The incision is made by some operators with a broad keratome (Fig. 72, p. 393); by others with a Hnear knife (p. 395)0 The linear knife is, in my opinion, to be preferred in every case. Its advantage is that it enables one, without danger to the lens, to effect a longer and more peripheral incision than can be made with the keratome. The latter, if introduced in a plane parallel with the iris, is liable to enter the chamber at some distance from its periphery, even though the external puncture be made well in the sclera; and if a sufficient length of incision is not obtained by the forward movement of the knife, it is extremely difficult to enlarge it satisfactorily during the withdrawal, for the chamber, already abnormally shallow, is instantly diminished almost to abolition, by the forcible escape of the aqueous humour. With the linear knife it is possible, even after the appearance of the point in the anterior chamber, to modify the length and position of the incision according to the space available, by making the counter-puncture a little further forward or backward, as may be necessary. The puncture is made in the sclera at about I Mm. from the corneal margin; the point of the knife is carried slowly and steadily across the upper part of the chamber, keeping near to the periphery, and passing very close to the anterior surface of the iris, but without wounding it, until it effects the counter-puncture in the correspond- ing spot. The distance between puncture and counter-puncture, externally, in a straight line, should be from 8 to 10 Mm. So far the blade of the knife should be kept parallel with the plane of the iris, but as it cuts its way out, and as soon as the angle of the chamber is incised between puncture and counter-puncture, the edge should be turned somewhat forwards, so as to emerge nearer to the corneal margin than it otherwise would. By this means the object desired—namely, an internal incision situated as peri- pherally as possible is attained, while a large conjunctival flap, which is undesirable, is avoided. T T
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