THE AVAILABLE data concerning molar concentration of the ocular fluids, though of great theoretic and practical interest to the physician, the physiologist and the pharmacologist, are in a very confused state. Final clarification of the problems involved is desirable, since on such data theories of origin of the intraocular fluid and water movements in the eye and its tissues are constructed; furthermore, the increasing interest in the production of isotonic fluids used for therapeutic purposes indicates the practical importance of these problems.
THE TEARS
According to the generally accepted concept, the tears are isosmotic with a 1.4 per cent sodium chloride solution, and the recommendation for adjusting the osmotic concentration of collyriums to this presumed tonicity has found worldwide acceptance. "Pharmacopoea Helvetica," 1933; "Pharmacopoea Gallica," 1937; "Dispensarium Danicum," 1934-1938, and "Pharmacopoea Svecica," 1943, all state that solutions for instillation into the eye should be isotonic with a 1.4 per cent