Effects of Nitroge$ Mustard on the Permeability of the Blood-aqueous Humour Barrier to Evans Blue 717 the Effects of Nitrogen Mustard on the Permeability of the Blood-aqueous Humour Barrier to Evans Blue

THE chemical warfare agent, "nitrogen mustard " or methyl bis (,8-chloroethyl) amine, has come to the notice of the clinician lately on *account of its beneficial effect upon Hodgkin's disease, the ieucaemias and some neoplasms (Gilman and Philips, 1946). It is also of interest to those studying the problems associated with the changes in the permeability in the blood-aqueous humour barrier since exposure of the eye to nitrogen mustard either in the liquid or vapour form results in a well marked iridocyclitic type of lesion which, in severe cases, may be associated with iris haemorrhages. Similar effects are obtained by dropping a one per cent. aqueous solution into the eye. The membranes separating the blood from the aqueouis humour show a high degree of selectivity; thus the aqueous humour is almost completely protein-free; sucrose, injected into the blood, appears in the aqueous humour only very slowly, whilst the trisaccharide, raffinose, does not appear in the aqueous humour at all (Weld, Feindel and Davson, 1942). Similarly, a large number of dyes, when injected into the blood stream, do not appear in the aqueous humour. (Halpert, German and Hopper, 1933, Amer. Ji. Physiol., Vol. CIII, p. 351). It was considered possible that the damage in the uveal tract caused by nitrogen mustard would manifest itself in the form of an increased permeability of the membranes separating the aqueous humour from the blood stream. If this were indeed the case, then it might be expected that a dye which, when injected into the blood of the normal animal, failed to appear in the aqueous humour, would appear in the aqueous humour of an animal whose eyes had been exposed to this chemical agent. Preliminary experiments showed this to be true; thus chlorazole fast pink, when injected into the blood of the normal rabbit, failed to appear in the aqueous humour; however, after exposure of the animal to nitrogen mustard vapour, the aqueous humour was found to be pink, indicating a change in the selective power of the membranes. The dye finally chosen for these experiments was