The Indian operation of couching for cataract

by Robert Henry Elliot

There are certain preliminary points which we must first settle:

1. There is no essential difference between the cases in which there is a definite cone of filmy or infiltrated membrane reaching from the optic nerve head to the ciliary body, and those in which deposits of a similar nature are found confined to the anterior portion of the vitreous chamber. The grounds for this statement are as follows: (a) An examination of the more complete specimens of conical exudate shows that the membrane becomes very slender as the nerve head is approached, and it is obvious that very little violence would be required to break this delicate thread across, and so to allow the whole membrane to be gathered up by its own elasticity towards its large and strong anterior attachments. (b) There is strong evidence in a number of the specimens of this series to show that the contraction of the shrinking inflammatory material within the globes takes place with such force as might easily suffice to break across the slender nerve attachment of some of these cones. (c) It is obvious that in not a few cases the tapering apex of a conical exudate is likely to be cut across during section of the globe, or broken across during subsequent manipulations. (d) Specimens in which the exudates presented a definite conical shape, when they were first cut in India, have arrived in this country transformed during the voyage into the similitude of those in which the exudate is loosely gathered into the fore part of the vitreous chamber; the apex of the cone had been broken off at the nerve head, and the exudate had moved forward by virtue of its own elasticity toward the anterior attachments of the mass. Taking all these points into consideration, we may conclude that in all the eyeballs which present the appearance of shrunken vitreous the structure was originally conical in form, and that departures from that shape are merely artefacts. Stress is laid on this point, because in a number of the globes the appearances present suggest that the exudate is poured out from the ciliary body, and is confined to the neighbourhood of that structure. We believe such an interpretation to be quite erroneous, and to be founded on the observation of artefacts.

2. Is this appearance of a shrunken vitreous body definitely pathological? The answer is in the affirmative, for the following reasons: (a) All these globes were treated alike, being dropped into 5 per cent. formalin solution on removal, and kept there till frozen and cut. (b) Normal eyeballs treated in this way present no such evidence of definite vitreous structure. (c) Every grade can be traced in the series before us, between the appearance of delicate filmy membranes in the vitreous and the presence of firmly organised structures. (d) Though it is very difficult to examine these exudates satisfactorily under the microscope, there are a large number of specimens which definitely show evidence of an inflammatory exudation, strengthening and thickening the vitreous body. In not a few of these the anterior hyaloid membrane (the term is used in a non-committal sense) is definitely thickened and infiltrated with inflammatory material (Pl. III., Fig. [20]). The conclusion arrived at is that these widely varying evidences of structural alteration in the vitreous body are to be interpreted as due to the penetration of the hyaloid by inflammatory material of chemotaxic origin, and to the subsequent organisation of that infiltration. (e) There still remains the clinical evidence. The author was increasingly reluctant, as his Indian experience accumulated, to remove lenses which had been couched. It was not that vitreous escaped, but that the results of operation were usually poor, and that the blame of the lost sight was then apt to be most unfairly ascribed to the extraction operation. In view of the frequent occurrence of vitreous changes, this failure to help the patients is easily explained. Major Kirkpatrick has taken a different, and possibly a more generous, view of the position, and has removed a number of these couched lenses. His evidence is of extreme interest in the light of our recent pathological findings; he has been “struck by the rarity of vitreous escape even after a fairly extensive investigation with a spoon” in extracting couched lenses. He adds:

“I have noticed that the vitreous body becomes shrunken and extraordinarily tough, so much so that when an eye is excised (either for glaucoma or for iridocyclitis following Mahomedan operation), the whole globe can be held up by a strabismus hook transfixing the vitreous, though the latter appears perfectly clear. The vitreous undoubtedly does undergo shrinkage, and leaves a large space, which is occupied by aqueous.”

Straub[2] has described some experiments which he made on animals, in the course of which he injected pathogenic organisms either into the vitreous or into the ciliary body. The result varied according to the part infected, and the poisoned area attracted leucocytes by chemotaxis to itself. Particular interest attaches to the following of his findings: (1) The optic nerve head was swollen and filled up with leucocytes; (2) there was evidence “that the lymph current of the vitreous goes by the optic nerve, and that chemotaxic substances are brought by this current from the granuloma (the artificial infection) to the nerve”; (3) the leucocytes found in the vitreous showed the way from the granuloma to the cup of the optic nerve—they were seated on thin membranes, and most of them were heaped together in small dots; (4) aggregations were found on the walls of the cavities of the eye (on the cornea, on the retina, on the lens capsule, etc.), attracted there, in Straub’s opinion, by a chemotaxic action.

In the experiments above considered, which were very limited in number, an effort was made to localise the infection to one or other part of the eye, and to work with a virus (tubercle bacilli) which was comparatively constant in its toxicity.

What Straub did with a few eyes has been done in the series now before us, by the Indian coucher, in fifty-four. The interest of the experiments is heightened by the fact that, whereas in the Dutch experiments the toxicity of the virus was kept as constant as possible, in the Indian ones it varied from that of organisms which took many years to destroy the sight to that of one which at once produced a fulminating panophthalmitis. One point more: The Indian operator made no effort to confine his procedure (and with that procedure went infection) to any one structure; sometimes he attacked the lens from in front, and in doing so he often primarily injured the iris, but may have spared the vitreous chamber; sometimes he entered through the ciliary body or through the choroid, opening up the hyaloid cavity in doing so. His want of skill and the slenderness of his anatomical knowledge made him catholic in the damage he inflicted, but running through his work is the trail of septic infection of the eyeball by penetrating wounds. The result is that he has provided us with a large material of extraordinary interest in the study of the problem which Straub started on.

The Filmy Masses in the Vitreous Chamber.—As has already been stated, the contents of the vitreous chamber in these specimens vary from thin gauzy films, which can only be detected by careful search, up to thick masses which strike the eye as soon as the specimen is looked at.

It is not easy to obtain a view of these exudates in section, but nevertheless they appear in a considerable number of the microscopic specimens, and their character is always the same; they consist of more or less structureless masses with blood-cells and leucocytes imbedded in their substance. In fact, they would seem to be identical with the membrane spoken of by Straub as harbouring the leucocytes which gave rise to dust-like and other opacities of the vitreous in his experimental cases. At a later stage, or perhaps in cases where the inflammation has been of a more plastic character, a distinct fibrillation of the exudate can be seen, and there may even be evidence of a definite fibrous tissue formation. If we confine our attention for the moment to those eyeballs in which the exuded mass is devoid of structure in the anterior portion of the cone, we shall find that, on tracing it back toward the apex by which it is attached to the optic nerve, it becomes more highly organised and more richly cellular, whilst fibrillation and fibrous tissue formation make their appearance. The same thing, though in a lesser degree, may be observed in the neighbourhood of the ciliary body, doubtless due to the presence of a plastic exudate derived from that structure.

An examination (Pl. VI., Fig. [38]) of the optic nerve and of the exudate attached to it reveals the following features: (1) The nerve head is congested, and its vessels stand out in prominent relief. (2) There is a considerable effusion of leucocytes in the neighbourhood of these vessels. (3) A mass of exudate fills up and projects from the optic nerve cup, whether this latter is physiological or glaucomatous. This mass is clearly contracting, and thereby pulling on the tissue which lines the edges of the cup. (4) Along the centre of the projecting exudate are to be seen (a) an abundance of mononuclear cells; (b) the commencement of a fibrous tissue formation; and (c) a new formation of bloodvessels.