in one form or another; and, on theoretical grounds, I believe that the simultaneous opening of the aqueous and vitreous chambers, or even the opening of the vitreous chamber only, may be a preferable proceeding to the evacuation of the aqueous chamber by a corneal puncture. But the disadvantage of these operations consists in this: they do not tend directly, as iridectomy does, to remove the obstructive changes at the angle of the anterior chamber; this region, if incised at all, is incised transversely, and the iris, an important element in the obstruction, is not removed. The operations in question have never gained a wide acceptance. (1)

In 1876 v. Wecker, in an article entitled " Glaucoma and Eye-drainage," gave a preliminary notice of a new method of treating glaucoma-viz., by the insertion through the tunics of a loop of very fine gold wire; and recommended its adoption in certain classes of cases-absolute glaucoma, hæmorrhagic glaucoma-cases in which high pressure persists in spite of iridectomy. (2) In a more recent article he recommends it only under more exceptional circumstances—namely, in cases of absolute glaucoma in which pain recurs again and again, and the patient nevertheless refuses to permit excision of the eye. From this it would appear that the operation has hardly justified the favourable expectations of its author. My own experience of it in three cases is anything but satisfactory, and inclines me to venture the opinion that it is unjustifiable in any case in which blindness is not already complete. For eyes which are totally blind, but which demand operative treatment for the relief of pain, my own conviction is that excision will, in the great majority of cases, be more truly beneficial than any other proceeding.

As regards the so called "drainage," I think it is by no 1 See note, page 231. 2 Arch. f. Ophth., XXII., IV., 209.

means certain that the operation deserves the name. An immediate escape of vitreous relieves the tension as in any other form of paracentesis, and may occasionally cause a glaucomatous condition to subside; but twenty-four hours later it will be found, in some cases at least, that high tension has returned. The subsequent excessive softening which occurs, and which, as v. Wecker states, may be permanent after the removal of the wire, is more suggestive of the lighting up of morbid changes within the eye, probably with detachment of the retina, than of a persistent draining away of the intraocular fluid. The operation appears to have been founded on the assumption that a diminished permeability of the sclera plays a part in the glaucomatous process, and to have been intended to re-establish something in the nature of an equivalent for this obstructed channel. We now know that such changes in the sclera have no existence in relation to the intraocular fluid, and that any channel of escape established through the choroid and retina is an entirely unphysiological one; such, at least, is the view which I have attempted to prove in the foregoing section.

Of the somewhat analogous proceeding—namely, trephining of the sclera-by which Argyll Robertson has attempted to effect a reduction of tension, I have no experience. The results recorded are not, I think, very encouraging for further trials, especially as it must now be granted that the operation, like the preceding one, has no power to restore the natural process of filtration.

ESERINE AND OTHER MYOTICS.

The power which myotics exercise over glaucomatous tension is a fact of comparatively recent discovery. Its importance ranks second only to that of the action of

iridectomy. Adolph Weber and Laqueur appear to have observed it independently of each other and almost simultaneously. (1)

The mode in which eserine acts upon the glaucomatous eye has already been suggested; it remains only to give proofs of its efficacy, and to lay down, as far as may be, the indications for its employment.

I abstract the following tonometrical measurements from two of the cases recorded in the Appendix:

In several cases of chronic glaucoma I have obtained no benefit from myotics either as evidenced by visual improvement or by perceptible reduction of tension. In one case of gradual recurrence of tension after iridectomy vision improved slightly during treatment with eserine; in two others no improvement was affected. In one case of acute glaucoma, probably supervening upon pre-existing chronic glaucoma in a somewhat advanced stage, eserine applied three times during the day before operation increased the chemosis very considerably, augmented the difficulty of the operation thereby, and was perhaps partly to blame for the unfavourable progress subsequent to operation. (1)

If we possessed a certain means of distinguishing the cases in which myotics are likely to be beneficial from those in which they may be hurtful, their value in the treatment of glaucoma would be greatly enhanced. Neither my own observations nor the published experience of others have as yet offered any decided information on this point, so far as I have been able to ascertain. Ad. Weber, in drawing attention to the efficacy of eserine, urged especial caution in its employment, inasmuch as he had observed its tendency to cause swelling of the ciliary processes to be productive of disastrous results. V. Wecker appears to use it before and after iridectomy in every case of glaucoma. Laqueur cites striking

1 Case 35, Section VII.

instances of its value, especially in acute attacks, and proposes it as a valuable means of reducing the difficulty of iridectomy in these cases. (1) He anticipates that it will obviate the performance of second iridectomies, and suggests that if its use were made known to the profession at large many eyes which are now lost during acute attacks for want of timely operative interference, might be saved from this disaster by removing or diminishing the urgency of the mischief. In a case of hæmorrhagic glaucoma he had to suspend its use at once by reason of the severe pain induced. He appears to have derived least benefit from it in those cases which, with deeply excavated disc, present but slight excess of tension, and good activity of pupil.

I have suggested, on theoretical grounds, that its efficacy depends in some cases upon a diminution in the diameter of the lens affected through the agency of the ciliary muscle. This explanation however, if true for some, can hardly be true for all cases, for amongst those cited by Laqueur is one of rapid disappearance of an acute attack in a patient aged 79. (2)

Another explanation is the withdrawal of the periphery of the iris out of the angle of the anterior chamber—i.e., out of its contact with the cornea, through the agency of the sphincter of the pupil.

The action of myotics upon the vessels of the eye, especially upon those chiefly concerned in the glaucomatous conditionviz., the vessels of the ciliary processes-appears to be of a kind likely to aggravate the condition rather than to relieve it. The ciliary processes swell under the action of eserine, calabar, &c.; and this I think explains the intensification of the vascular symptoms-e.g., chemosis-which sometimes follows their employment.

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1 Arch. f. Ophth., XXIII. III., 149. 2 Arch. f. Ophth., XXIII., III., 168.