On retrobulbar incision of the sheath of the optic nerve in cases of swollen disc / by Robert Brudenell Carter.

  • Robert Brudenell Carter
Date:
1887
Catalogue details

Licence: Public Domain Mark

Credit: On retrobulbar incision of the sheath of the optic nerve in cases of swollen disc / by Robert Brudenell Carter. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    number of cases in which, in connection with the growth of intra-cranial tumours, or with other morbid processes, there has been great swelling of the intra-ocular extremities of the optic nerves. In many cases of this kind sight is at first absolutely unaffected, the swelling being limited to the connective tissue of the disc and of the fibre layer of the retina, and being apparently produced by a moderate amount of mechanical impediment to the circulation, not enough either to arrest conduction through the nerve fibres, or to close the channels of the vessels. In some instances the swelling of the optic discs has disappeared under treatment, and complete recovery has ensued. In others, nerve atrophy and blindness have been produced ; and these consequences may, I think, be explained in two ways. If I may dwell for a moment upon the anatomy of the parts concerned, it will be to remind the reader that the optic nerve is closely invested by a sheath derived from the pia mater, and this again, but loosely, by a sheath derived from the dura mater. Between these two sheaths there is an interval, or inter-vaginal space, which terminates in a cul-de- sac at the level of the back of the eyeball, where the dural and pial sheaths unite to blend with the sclerotic. This inter- vaginal space contains membranous processes derived from the arachnoid, and communicates with the sub-arachnoid space; so that, as was shown by the authorities cited by Dr. de Wecker, an excess of sub-arachnoid fluid will make its way into the intervaginal space, compressing the nerve trunk and distending the dural sheath, which, especially in the immediate neighbourhood of the eye, has often been found to be much dilated. The central artery and vein of the retina pierce the sheaths at a point which is from fifteen to twenty millimetres behind the eye : and it is manifest that compression of the lower part of the nerve trunk, in which the vein is still con- tained, must impede the return of blood, and must occasion dropsical swelling of the nerve termination within the eye, and of the adjacent retina, with turgescence of the retinal branches of the veins. The effect of such compression must depend upon its degree, and experience shows that it may be sufficient to produce distinct dropsical swelling, and that this may continue (within my own knowledge for more than three years) without any affection of the sight. On the other hand, the compression of the nerve trunk as a whole may increase so ra])idly and to such a degree as quickly to destroy vision by arresting conduction through the fibres; in which case it must also arrest the flow of blood through the vein, an occurrence usually attended by hsemorrhages into the retina. When the compression increases more slowly, the consequent dropsical effusion mav excite inflammation of the connective tissue of
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