AN UNPIGMENTED PRIMARY TUMOUR OF THE OPTIC DISC (A contribution to the knowledge of the Phakomata of the Eye)

PRIMARY tumours of the optic disc are generally rare.'They pro- vide the clinician with difficulties, and the diagnosis is not an easy one.It is necessary to distinguish the growth from an inflamma- tory manifestation and from a congenital anomaly.Then the question arises as to whether the growing tissue is a benign or a malignant growth.The answer to this question is often so impossible that our uncertainty leads us to the decision to excise the affected eye, even when its function is still preserved.Even then, when we are in a position to study the growth histologically, our ignorance of the cellular structure of these blastomata is still over- whelming.The tumours of the optic disc are especially interesting from the general paihological, point of view.The blastomic character of this growing tissue is mostly unrecognisable in the cases of phakomata.