Uveoscleral outflow: Diffusion or flow?

Shallow peripheral ciliochoroidal detachments with 10^-4 M fluorescein isothiocyanate dextran 70 were created in cynomolgus monkey eyes. Anterior chamber fluorophotometric readings were taken for 6 hr. From the anterior chamber fluorescence values, the rate of tracer movement from the supraciliary space into the anterior chamber was calculated. The rate of movement was 0.003 μl/min, expressed in equivalent volumes of tracer solution. This value is more than 200 times lower than the rate of tracer movement from the anterior chamber to the supraciliary space. It is concluded that tracer movement from the anterior chamber to the supraciliary space (uveoscleral route) results from fluid flow rather than diffusion.