Effect of Cocaine upon Protein Content of Regenerated Aqueous Humor

Abstract

The normal aqueous humor resembles in its composition a dialy-sate of the blood plasma with the normal capillary wall acting as dialyzer. When this aqueous is removed a “second’ aqueous is formed which in animals contains considerably more protein than the original fluid. This second or regenerated aqueous is generally thought to be formed by filtration of plasma through abnormally permeable capillary walls. If the paracentesis is done after retrobulbar injection of adrenaline or during stimulation of the sympathetic, the new-formed aqueous contains only slightly more protein than the normal one. In man the difference between the intraocular fluid of new formation and the normal fluid is less marked. Some writers have suggested that there is no increase in the protein content of the human aqueous after paracentesis. More accurate techniques have demonstrated that an increase of protein, although small, does occur (Table I), Two factors have been suggested as possibly having some influence upon the protein content of the second aqueous, viz., the time interval between the withdrawal of the first and the second aqueous and the anesthetic used. Mestrezat and Magitot 1 conclude from their small series of cases that the protein content of the regenerated aqueous in man reaches its maximum about 45 minutes after the first paracentesis. Wessely 2 has pointed out that anesthetics with pronounced vasoconstrictor action like cocaine are likely to lower the protein content of the second aqueous. He has, however presented no proof for this view.

We have had the opportunity to determine the protein content of the first and second aqueous on a small number of practically normal human eyes. Under local anesthesia the aqueous was aspirated by needle puncture and its protein content determined by nephelometry of the opacity produced by precipitation of the protein with sulphosalicylic acid. 3