AN EXPERIMENTAL - APPROXIMATION TO THE LAW OF GOLDMANN - STUDY OF THEDYNAMICS OF THE AQUEOUS-HUMOR OUTFLOW

Purpose: The law of Goldmann constitutes a theoretical approximation t o the aqueous humor outflow mechanism, but its validity has not been e xperimentally confirmed and there are many factors that could possible alter the principles on which it is based. The authors' (P.B., P.C.F. , and T.M.P.) goal is to verify if that is accomplished experimentally . Methods: Forty-eight eyes were studied, 21 of which correspond to no rmal subjects, and 27 to glaucoma patients. The following determinatio ns were done: (1) aqueous humor flow (F; by fluorophotometry; (2) outf low facility (C; by tonography); and (3) intraocular pressure (IOP; by applanation tonometry). In this way, the authors verified the accurac y by which the fluorophotometric flow cooresponds to that obtained fro m the Goldmann formula and the measurements of C and IOP done for each eye separately (the authors assigned a constant value of 9 mmHg to th e episcleral venous pressure). Results: The values of F, C, and IOP ar e 2.2+/-0.6 mul/min, 0.16+/-0.05 mul/min/mmHg, and 18+/-3.9 mmHg for t he total sample. In normal subjects, the authors obtained F=2.1+/-0.5 mul/min, C=0.24+/-0.03 mul/min y IOP=15+/-3 mmHg. In glaucoma patients , the authors obtained F=2.2+/-0.7 mul/min, C=0.13+/-0.05 mul/min/mmHg , and IOP=22.1+/-4.3 mmHg. No correlation between the F values obtaine d by fluorophotometry and those obtained from the Goldmann formula was observed, the difference between them being more than 1 mul/min in 47 % of the eyes. Conclusions: The equation of Goldmann has not been expe rimentally verified. Some of the responsible factors could be due to t he errors inherent to the measuring techniques or to the existence of the uveoscleral flow that are not contemplated in the formula. However , observing the great difference existing between the two terms of the equations, the authors believe that the concept of the drainage syste m of the aqueous humor as a passive pressure-dependent mechanism, simi lar to a rigid tube, contained in the law of Goldmann, may not be corr ect.