The Measurement of Rate of Aqueous Flow With Iodide

¹ Department of Ophthalmology and the Oscar Johnson Institute, Washington University School of Medicine, St. Louis, Mo.

Trace amounts of iodide are transported out of the rabbit eye in such a fashion that this anion accumulates in the aqueous humor of the anterior chamber exponentially with time. Iodide is therefore a useful anion for estimating the coefficient of aqueous fiow and requires punctures of the anterior chamber only. The method can be used in two eyes of one animal, or with the use of two or more isotopes of iodide, can be applied to a single eye. The iodide method, demonstrates a fiow coefficient of 1.5 per cent of the anterior chamber per minute in the normal animal. It is reduced by some 45 to 50 per cent folloioing acetazolamide, by 80 to 90 per cent during hypothermia (18 to 20° C), and by an average of 17 per cent on the side of carotid ligation. Topical pilocarpine appears to increase the fiow coefficient by an average of 16 per cent and atropine to decrease it by 21 per cent.