Intravenous Urea Therapy in Glaucoma.

THE use of intravenous urea as a therapeutic agent is a recent development in the medical treatment of glaucoma and this paper reports a clinical evaluation of the drug in 43 cases. The first account of urea being given intravenously would seem to be that of Tanner (1852) in a paper on the use of oral urea as a diuretic, where he mentioned that "half a drachm" of urea, prepared from urine, had been given into the vein of a dog. This resulted in "an excessive secretion of urine, so that the place where the animal was kept was literally flooded in an hour or two by the frequency and quantity of his micturition". The use of intravenous urea lay dormant until Hertel (1914) studied the effect on the intra-ocular pressure of giving various substances intravenously, including sucrose and urea. Duke-Elder (1926) revived interest in this form of therapy by showing that hypertonic solutions were effective in reducing the intraocular pressure whilst isosmotic solutions produced little change. Working with animals and using 50 per cent. urea intraperitoneally, Fremont-Smith and Forbes (1927) compared the fall in intra-ocular pressure with cerebrospinal fluid pressure and noted that the ocular tension fell less. However, the modern development of the use of urea in osmotic therapy in acute glaucoma stems from the work of Javid and his collaborators (Javid and Settlage, 1956; Javid, Settlage, and Monfore, 1957; Javid, 1958; Javid and Anderson, 1959) who established the safe combination of 30 per cent. lyophilized urea in 10 per cent. invert sugar and actually used this agent in a few cases of glaucoma. Advantage of this work was taken by Galin, Aizawa, and McLean (1959, 1960), who published the first account of the clinical use of this drug in acute glaucoma.