The Indian operation of couching for cataract

by Robert Henry Elliot

Fig. 44 (No. 111).—Left eye, whole section.

Fig. 45 (No. 131).—Left eye, lower half.

Macroscopic Cysts of the Retina.—It remains to speak of larger cysts of the retina which can be recognised by the naked eye. It has already been mentioned that, in those cases in which this membrane has been found to be tightly folded on itself, a pseudo-cystic condition is thereby produced; the cavities of these false cysts are merely shut-off portions of the original vitreous chamber. Of a quite different nature are the true cysts of the retina, three examples of which are to be found in this collection. In one (Pl. II., Fig. [12]) a narrow slit-like cyst is seen in the outer layers of the detached retina at its lower part. In the second, a whole-section of the globe shows a large cyst occupying the central region, the macular area forming a portion of its wall (Pl. VII., Fig. [44]). Lastly, in the third a large round cyst can be seen to the temporal side. A point of interest in connection with this specimen is that it shows both true and false retinal cysts (Pl. III., Fig. [19], and Pl. V., Fig. [31]).

The Choroid.

It remains to add a few words to what has already been said about this membrane. The great majority of the changes we have found in it are, clearly, to be attributed to the effects either of hypertony or of hypotony of the eye; they do not, therefore, differ from similar appearances found under the same conditions generally.

Compared with detachments of the retina, those of the choroid are rare in this series. In one instance, already mentioned, the two membranes had been displaced together by the instrument used in couching (Pl. V., Fig. [30]). In another, in which severe inflammation had occurred, the retina and choroid had adhered to each other, and had been detached as one sheet by the contraction of an exudate, which lay in the neighbourhood of the iris and ciliary body and in the front part of the vitreous cavity. In a number of other globes, in which the tension was low, the ciliary body and the anterior portion of the choroid were found separated from the sclera as far back as the line where the anterior segment of the latter coat was drawn over the posterior in the manner pointed out by Treacher Collins in his work on Hypotony (Trans. of the O.S. of the U.K., 1917).

In the previous chapter we have spoken of an appearance commonly seen in successfully couched eyes—viz., an unusual distinctness of the large vessels of the choroid in the ophthalmoscopic picture. It is necessary to insist that in such cases the vessels are not sclerosed; they are seen with unusual distinctness simply because the pigment which usually hides them from view has disappeared. What is more, a careful study of a number of these cases has created a strong impression that the deficiency in pigmentation affects both the pigmentary layer of the retina and also the pigment of the choroid. The absence of the former lays bare what lies behind it; the absence of the latter is inferred from the general appearance of pseudo-albinism. These findings are the more noteworthy by reason of their contrast to the usual deep pigmentation of the Indian eye. Some of our specimens throw light on this phenomenon, for we observe in them two changes: (1) The pigmentary layer of the retina is irregularly thinned and altered, and at some points its pigment can be seen migrating into the choroid; (2) the choroidal pigment itself is extensively altered in an irregular manner, being heaped up in some areas and thinned in others. It is necessary to remember that, inasmuch as our specimens are wholly obtained from the coucher’s failures, whilst the interesting appearance we are discussing is best seen in his successes, we cannot expect very definite results from our pathological material, since the changes we desire to study are there overlaid and obscured by those of pathological processes, such as hypertony, hypotony, and inflammation.

Glaucoma.

It has long been known that couching is frequently followed by secondary glaucoma. In the present series of 54 globes, 19 of them showed evidence of high intra-ocular pressure. This figure must not, however, be taken as a reliable index of the numerical frequency of glaucoma as a complication of the operation. On the one hand, we must remember that the present series deals with the failures only, and that a large number of eyes are met with clinically in which the lens is floating free in the vitreous chamber without any sign that the intra-ocular tension is raised. Again, the cases which go on to suppuration, and which are very numerous, are excluded from the present series owing to the fact that all such were eviscerated in order to avoid the risk of intracranial sepsis. This obviously diminishes the total number of globes under consideration, and thereby raises the apparent percentage of other conditions, such as glaucoma. On the other hand, it would be a mistake to suppose that out of these 54 globes only 19 had suffered from secondary glaucoma, for in 24 of them a complete detachment of the retina had covered up any evidence which may at some time have existed of the presence of increased intra-ocular pressure, though the conditions still found in some of them make it more than probable that the globes were formerly glaucomatous. In any case, it leaves us with the fact that, out of 30 eyeballs which were available for accurate examination, no less than 19 were glaucomatous. In 17 of the 19 the angle of the anterior chamber was extensively closed, and in 3 of these the chamber was so shallow as almost to be reduced to a potential slit. The remaining 2 are thus accounted for: In one the angle was open save for a small marginal adhesion, and there was free communication between the aqueous and vitreous chambers; unfortunately, the specimen was almost spoilt in sectioning it for the microscope; in the second, a Morgagnian lens was impacted in and had blocked the angle of the anterior chamber.