Manometric Studies of the Pressure-volume Relationship in Living and Enucleated Eyes of Individual Human Subjects.

IN a previous investigation a significant difference was found in the pressure response of the living and dead eyes of individual rabbits when a given volume of fluid was injected into the eye (Eisenlohr and Langham, 1962). An increase in the intra-ocular pressure of living animals was found to force blood from the eye and the amount lost per unit pressure increase was found to reach a maximum as the pressure approached the arterial blood pressure. The observations were made by recording manometrically the response of the intra-ocular pressure either to a sudden injection of a predetermined volume of fluid given in ascending and descending pressure steps or to a continuous infusion of saline at a rate greatly exceeding the outflow of aqueous humour. The latter method gave a continuous function of the pressure response of the eye and had the merit that observations over a wide range of pressures could be completed within 10 to 15 seconds. It is the purpose of this study to apply these techniques to the living and freshly enucleated eyes of individual subjects to determine whether vascular changes within the human eye significantly modify its pressure-volume relationship. Since this work was begun, Ytteborg (1960a,b) has investigated this problem in a somewhat different manner. The results and conclusions to be reported in this paper agree in some but not in all respects with those of Ytteborg, and the reasons for the differences are discussed.