The effect of colchicine on aqueous humor dynamics

The plant alkaloid, colchicine, which binds specifically to tubulin, was studied for its effect on aqueous humor dynamics in the rabbit. Topical application of either 50 or 100 μg of colchicine resulted in a significant lowering of intraocular pressure after 24 hr. Colchicine significantly increases the rate of aqueous humor outflow while having no effect on aqueous inflow. Intraocular pressure returns to baseline despite continued administration of colchicine, which results in severe ocular toxicity. This study suggests that the aqueous outflow system contains microtubules or membrane-associated tubulin, the integrity of which is necessary for the maintenance of intraocular pressure.