Retrolental Decompression for Malignant Glaucoma.

IN 1869 von Graefe described a complication following operations for glaucoma in which a shallow or absent anterior chamber was associated with severe intra-ocular pain and a greatly increased intra-ocular pressure. This condition carried with it an extremely poor visual prognosis due to its resistance to any form of treatment. The passage of the years has done little to diminish the problem of malignant glaucoma. Indeed it has defied attempts at both prevention and cure with considerable success. Even the aetiology is far from certain, although it is now suspected that there may be certain predisposing factors which make a malignant course more likely to follow in the post-operative period. These are a shallow anterior chamber and a high ocular tension at the time of the operation (Chandler, 1950; Birge, 1957) and a lens relatively too large for the eye (Priestley Smith, 1879). However, these qualities are undoubtedly present in many eyes that do not pass into malignant glaucoma (Tamler and Maumenee, 1955), and some other precipitating mechanism must be present in those that do so. At the onset of the condition there is a considerable forward movement of the lens iris diaphragm. It is thought that the relatively enlarged lens then blocks the angle since, because of its relative disparity in size with the rest of the eye, the circumlental space is not wide enough to allow seepage of aqueous round the equator. This forward movement may be due to a variety of causes. Heerfordt (1915) suggested that uveal congestion was at fault, the engorged ciliary body forcing the lens forwards from behind. Chandler (1950) considered that this could be the cause in three of his six cases although he made the point that vasomotor instability was common in glaucoma, but malignant glaucoma occurred only in 2 per cent. of glaucoma operations; this mechanism was thus unlikely to be a potent cause in the majority of cases. As an alternative, Shaffer (1954) postulated that aqueous did not flow forwards into the anterior chamber at the onset of the condition, but passed backwards, either directly into the vitreous, or behind it, detaching the