Uveoscleral outflow

A second pathway, uveoscleral outflow, comprises the other 20% of aqueous humor drainage. In the uveoscleral pathway, aqueous humor exits the anterior chamber through the iris root and through spaces in the ciliary muscles, which then drains into suprachoroidal space. Uveoscleral outflow can be pharmacologically modulated by adrenoceptors, prostanoid receptors, and prostamide receptors.4,10,12-15... 

Brimonidine Alphagan P Solution 0.15, 0.1 1 drop two to three times a day to also increase uveoscleral outflow... 

F2o, analog uveoscleral outflow and to a lesser extent trabecular outflow... 

Pharmacology Brimonidine is an alpha-2 adrenergic receptor agonist. It has a peak ocular hypotensive effect occurring at 2 hours postdose. Brimonidine has a dual mechanism of action it reduces aqueous humor production and increases uveoscleral outflow. 

Topical PGE2 and PGF2qi significantly reduce intraocular pressure for at least 24 hours and are used in the treatment of glaucoma. Derivatives of the isopropyl ester of PGF2qi appear to be the most effective. Transient ocular adverse effects include conjunctival hyperemia, local irritation, intermittent photophobia, and pain in the eye (66-68). Newer derivatives, such as latanoprost, travoprost, and bimatoprost, appear to be better tolerated, with less severe and less frequent adverse effects (69). They reduce intraocular pressure by increasing uveoscleral outflow. 

Unoprostone is a synthetic prostaglandin analogue of PGF2a used in the treatment of glaucoma. Its mechanism of action is believed to be by enhancing uveoscleral outflow, like latanoprost. 

Latanoprost, a topical prostaglandin, is used in humans and in small animals to reduce lOP by increasing uveoscleral outflow. In the horse, a topical ophthalmic preparation of 0.005% latanoprost reduces lOP in treated eyes however. 

The aqueous humor flows out the eye mainly via the conventional route of the trabecular meshwork and Schlemm s canal. However, about 10-20% of outflow is via the uveoscleral (nonconventional) route whereby the aqueous humor passes between the ciliary muscle bundles and into the episcleral tissues, where it is reabsorbed into orbital blood vessels and drained via the conjunctival vessels. The IOP-lowering effect of these prostanoid drugs occurs predominantly through enhancement of uveoscleral outflow [26], although unoprostone and bimatoprost also increase flow via the trabecular meshwork to a lesser extent. 

Gaton DD, Sagara T, Lindsey JD, Gabelt BT, Kaufman PL, Weinreb RN. Increased matrix metalloproteinases 1, 2, and 3 in the monkey uveoscleral outflow pathway after topical prostaglandin F(2 alpha)-isopropyl ester treatment. Arch Ophthalmol 2001 119 1165-1170. 

Bimatoprost is a prostamide, a synthetic prostaglandin structural analogue used worldwide for glaucoma treatment. Bimatoprost uces lOP primarily by increasing aqueous humour outflow via the uveoscleral outflow pathway bimatoprost also appears to act via the trabecular meshwork. 

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