Returning to the 17 cases in which the angle of the chamber was closed, and to certain other eyeballs in which it seemed probable that glaucoma had at some time been present, we found that in every one of them one or other of the accepted causes of secondary glaucoma was revealed when looked for; in some, more than one such cause was discoverable. We shall content ourselves with enumerating these factors.

A corneal fistula, with evidence of past anterior staphyloma, was present in one; here the cause of the glaucoma was evidently the closure of the filtering angle, which resulted from the anterior synechia; in one there was a capsulo-corneal synechia (Pl. IV., Fig. [24]), and in another a retino-corneal synechia (Pl. IV., Fig. [25]); in 5 the ciliary body was involved in the scar; in 6 the dislocated lens pressed extensively on the iris base (Pl. VII., Fig. [45]); in 3 the lenses, tilted at right angles to their normal position, pressed the anterior hyaloid membrane severely back on the side of the dislocation, whilst causing the vitreous to bulge the iris forward into the anterior chamber on the opposite side; in 5 the pupil was blocked, and in 3 of these l’iris bombé was present; in 2 the anterior layers of the hyaloid were so thickened by inflammatory exudate as to suggest that there was an abnormal obstruction to the passage of fluid across the membrane; in one a marked thickening of the lens capsule in the form of an after-cataract may possibly have provided an obstruction to the forward passage of fluid from the vitreous; lastly, there is one globe in which glaucoma had probably been present before the operation, if one may judge from the history of the case and from the violent hæmorrhage which followed the couching.

It has been suggested that one of the causes of glaucoma after this operation is an advance of the front part of the vitreous body owing to a rupture of the anterior layers of the hyaloid during the operation. Without in any way denying that the suggestion may be a valid one in certain cases, the impression gained from a study of this series is that we need look no farther than the well-recognised causes of secondary glaucoma. We have only to remember that the trauma inflicted is extensive and various, and that a greater or less degree of sepsis accompanies every couching in the hands of its Indian exponents.

CHAPTER VI
DIAGNOSIS

The diagnosis of a case of couched cataract presents the surgeon with three distinct problems: (1) To ascertain whether a couching has been done or not; (2) to discover the new position of the lens and its condition; and (3) to decide whether it is advisable to operate. Only those who work in lands, where the couching of cataracts is an everyday occurrence, will take a deep concern in such questions; but the subject has a scientific interest which cannot fail to appeal to any one who devotes his serious attention to the large questions of ophthalmology.

It might be thought that the simple and obvious way to ascertain whether a couching had been done would be to ask the patient or his relatives. In a large number of cases this is of course sufficient; but in India, at all events, there are many who will deny the operation they have undergone. This is due to the fact that it is widely known among the people that the British surgeons view the coucher and all his methods with extreme disfavour. Patients are therefore reluctant to admit having consulted him, and they also are afraid lest treatment should be refused them, once their true history is known; for it is common knowledge amongst them that the Western practitioner is extremely reluctant to interfere with an eye which a coucher has spoilt. It is well, therefore, to consider carefully the grounds on which the physical diagnosis of a couched lens should rest.

We will first consider the case of those eyes in which the cataract has been definitely removed from the neighbourhood of the pupil. These present certain well-marked signs: (1) The pupil is brilliantly black, and (2) the plane of the iris is flat. It may seem strange to insist upon these points, but to the trained eye they are so obvious that a diagnosis can often be made, as soon as the patient takes his seat in the out-patient room, in front of the surgeon. The quality of the blackness of the pupil is difficult to put into words, but it arrests the attention by its contrast to the ordinary appearance of the pupil in people so advanced in life as the subjects of cataract usually are. The phenomenon is due to the whole cataract, capsule and all, being thrust away from the pupillary area, and it can be equally well seen in cases which have undergone the intra-capsular operation. Then, with regard to the flattening of the iris, the trained eye is used to the appearance presented by the slight forward convexity of that membrane as a result of the presence of the lens behind it; whereas the complete removal, not merely of the lens, but also of the support of the suspensory ligament, makes the iris flatten out in its own plane.

On close inspection we notice other signs. (3) The iris, deprived of the support of the lens, is often tremulous. This can best be observed if the patient is bidden to move his eye sharply in different directions. (4) Scars may be seen on the iris. These are the result of tears of the membrane during the operation. In some cases they are associated with an irregularity of the pupil, which may be extreme, or with a limitation or absence of pupillary movements. In other cases the immobility of the pupil, which may be absolute, is associated with (5) an atrophic condition of the inner free margin of the iris. Such a condition is only met with in very long-standing cases. Transillumination of the eye will sometimes show up the scars, or the atrophic condition just referred to, as light spaces against the rest of the dark background of the iris. (6) A careful study of the cornea, or of the sclera in its neighbourhood, will often reveal evidence of the wound made by the instrument during couching. In the cornea these take the form of small nebulæ or leucomata, lying just within the limbus, and usually in the temporal quadrant. In one case a persistent fistula was met with, as the result, presumably, of the bursting of a staphyloma along the original track of a septic wound. Scars in the sclera are much more difficult to distinguish, but they can sometimes be detected by the pigmentation which overlies them; such pigmentation may be due to the inclusion of uveal pigment in the track of the wound, as has been shown by our pathological specimens: but this is not the only possible explanation of the discoloration, for in dark-skinned races a certain amount of pigmentation is not uncommon after injuries of the conjunctiva. In one of the eyes we examined, there was a filtering scar over a fistula which had formed along the track of a scleral wound. (7) We come now to the leading feature in the diagnosis of these cases—viz., the recognition of the displaced cataract in its new position within the eye. In the rare event of a lens being dislocated into the anterior chamber and fixed there, its presence can be easily recognised. Again, in a large number of the cases which present themselves in the out-patient room, the cataract can be seen floating freely in the vitreous, and bobbing up and down with the movements of the eye. In the case of the milky Morgagnian cataracts, or of those cortico-nuclear cataracts which present a glistening and pearly-sectored appearance, it would be difficult even for a beginner to fail to see the lens, which usually lies at the lowest part of the eye. As the patient sits in front of the surgeon, the gleam of the white cataract can be caught each time he looks downward, even though a distance of two or three feet may separate him from the observer. In the case of darker cataracts, such as the pigmented nuclear ones, frequently met with in Indian practice, a closer examination is required.

The patient must be brought nearer to the observer, and facing a good source of illumination. The surgeon then focusses the light on the pupil by the aid of a lens, bidding the patient at the same time to look downward. If this fails, the patient is instructed to bend his head forward, holding the face horizontal; the surgeon then places one closed fist on the back of his head, and gives a number of sharp raps on it with his other fist; when this is done, it is often found that the lens has floated forward on to the pupil. If the patient’s head be now quietly raised, the lens can be seen dropping gently away from the pupil, which turns from white or brown (according to the nature of the cataract) to black as it does so. The experiment can be repeated again and again. Sometimes the lens falls away from the pupil so quickly that the surgeon must stoop down and look up at the eye in order to see it. If even after this test he fails to see the cataract, it is safe to assume that it is tied down in its new position by inflammatory adhesions excited by the septic matter introduced at the time of operation. Such adhesions may consist merely of delicate fibrils of exudate, which slightly increase the consistency of the vitreous body, and so to a small extent limit the excursions of the lens; or they may be represented by firm and highly organised fibrous tissue, which mats the lens in its new position, and which may be so strong that even a post-mortem dissection would fail to disengage the cataract from its adventitious position. This subject has been dealt with much more fully in the chapter on pathology. The dilatation of the pupil by a mydriatic will often make it quite easy to discover the whereabouts of the cataract, especially if a strong light, whether natural or artificial, is focussed on the eye by means of a lens. Natural light is preferable to artificial if possible, especially in a country like India, where powerful daylight can be counted on during a large part of the year. The advantage of the white light is especially marked when dealing with brown or dark-coloured cataracts. An examination with the ophthalmoscope or with a transilluminator may sometimes be of value, but in the class of cases we are now discussing, these are seldom of much use, if the examination just described fails to reveal the whereabouts of the cataract.

There remain a few points of interest which deserve mention. Though in the great majority of couched eyes the cataract lies in the lowest part of the globe, it may be found either to the inner or to the outer side, or even in the upper half of the eye. Sometimes it flaps backward and forward with the movements of the globe, swinging on a hinge, which evidently consists of the remaining fibres of the suspensory ligament, and which may be situate in any possible direction, though most often it lies below. It will be readily understood that if this hinge is situate below, or to the inner or outer sides, the lens will flap away from the pupil downward, or to the hinged side, as the case may be. It is not inconceivable that, in repeatedly doing so, it may inflict some measure of injury on the neighbouring part of the ciliary body and retina, and may thus excite a local inflammation which will tend in time to tie the cataract permanently in the new position towards which it flaps, away from the pupil. In the event of the hinge being in one of the three directions now under discussion, the cataract will tend to fall forward on to the pupil only when the patient stoops forward, so as to bring his face into the horizontal plane. When the hinge is situate above, the latter is one of the few positions of the face in which the pupil clears itself in ordinary cases; but one meets with instances in which, despite the hinge being above, the pupil remains clear except when the face is horizontal, the lens lying most of the time in the upper segment of the eye. There is another factor, and probably a more frequent one, than that of the local injury inflicted by the lens during its movement, which tends to tether it in situ. This is the increasing consistence of the vitreous, due to the deposit within it of inflammatory matter, a point which has already been alluded to.