Before considering this subject in the light of the pathological specimens before us, it is necessary to make certain preliminary statements:
1. Inasmuch as all our material is derived from blinded eyes, it is obvious that we are dealing with the coucher’s failures alone, and are excluding his successes. In a very large percentage of the latter the lens is seen, during life, to be floating freely in the vitreous, apparently untrammelled by adhesions.
2. The position in which we find the lens on bisection of the eyeball is not necessarily that into which it was thrust at the time of operation, for the changes which occur in the eye as a result of inflammatory action may profoundly alter the position into which the lens was originally forced by the coucher. Nor must we forget that in those globes, in which the cataract is not tightly tethered by adhesions, gravity plays a part.
Having thus cleared the ground, we may start with the statement that, though the lens may be displaced in any direction within the sclero-corneal coat, backward dislocations are by far the most common, whilst forward ones were only found 4 times in the whole series of 54 globes. None the less, each of these latter cases possesses considerable interest.
Forward Dislocations.—(1) In No. 8[1] the couching instrument passed through the limbus, and the track of the wound can be plainly followed in microscopic sections. The ciliary body was pushed bodily away from the sclera, and the lens nucleus was forcibly thrust into the space formed by this cyclodialysis (Pl. II., Fig. [10]); it is to be seen imbedded in a mass of inflammatory exudate, whilst its capsule, with some of the cortex, lies in the normal situation.
(2) In No. 44 the capsule and the nucleus of a Morgagnian cataract are seen floating in the vitreous chamber (Pl. II., Fig. [11]). During life the nucleus frequently passed backwards and forwards between the aqueous and vitreous cavities. The same phenomenon, though rare, has been observed in other couched eyes.
(3) No. 61 is probably an instance of the same kind of thing having happened at an earlier period (Pl. II., Fig. [12]). Now, however, the small dark Morgagnian nucleus is seen fixed in the lower part of the anterior chamber, into which it doubtless gravitated by its own weight, and there set up inflammatory mischief, which led to its adhesion to the surrounding parts, and to its becoming fixed in situ by the formation of organising exudate.
(4) In No. 108 the only evidence of lens material present was the capsule of a Morgagnian cataract, which lay impacted in the lower part of the anterior chamber (Pl. II., Fig. [13]). On section, Morgagnian fluid escaped, and no trace of a nucleus could be detected. It is of interest to record that the writer has, on a number of occasions, operated on Morgagnian cataracts in which the lens nucleus had been reduced to the thickness of a lamellar disc, or in which no trace of a nucleus could be detected. In this case no adhesions had formed, and during the transit of the specimen to England the capsule fell from its position to the bottom of the bottle.
Fig. 10: Specimen No. 8, Whole-Section.—The lens can be seen dislocated between the ciliary body and the sclera; the pectinate ligament had been ruptured at the operation.