Purpose.: Mice are commonly used in glaucoma research, but relatively little is known about aqueous outflow dynamics in the species. To facilitate future use of the mouse as a model of aqueous humor outflow, several fundamental physiological parameters were measured in the mouse eye.

Methods.: Eyes from adult mice of either sex (C57BL/6 background) were enucleated, cannulated with a 33-gauge needle, and perfused at constant pressure while inflow was continuously measured.

Results.: At 8 mm Hg, total outflow facility (C total) was 0.022±0.005 μL/min/mm Hg (all values mean±SD; n= 21). The flow–pressure relationship was linear up to 35 mm Hg. The conventional outflow facility (C conv) was 0.0066±0.0009 μL/min/mm Hg, and the unconventional outflow (F u) was 0.114±0.019 μL/min, both measured at room temperature. At 8 mm Hg, 66% of the outflow was via the unconventional pathway. In a more than 2-hour-long perfusion at 8 mm Hg, the rate of facility change was 2.4%±5.4%(n= 11) of starting facility per hour. The ocular compliance (0.086±0.017 μL/mm Hg; n= 5) was comparable to the compliance of the perfusion system (0.100±0.004 μL/mm Hg).

Conclusions.: Mouse eyes are similar to human eyes, in that they have no detectable washout rate and a linear pressure–flow relationship over a broad range of intraocular pressures. Because of the absence of washout and the apparent presence of a true Schlemm's canal, the mouse is a useful model for studying the physiology of the inner wall of Schlemm's canal and the conventional outflow tissues.