Does the Renin-Angiotensin System (RAS) Regulate also Intraocular Pressure (IOP)?

The central role of Renin-Angiotensin System (RAS) in the regulation of blood pressure is widely accepted, and drugs which inhibit the formation of the potent vasoconstrictor angiotensin II (AngII) i.e. ACE inhibitors or drugs which block the Ang receptors of type 1 (AT1R) form the cornerstone in the treatment of hypertension. However, from AngI and AngII also vasodilating and blood pressure lowering products, such as Ang(1-7) are formed by another ACE isoenzyme (ACE2). Ang(1-7) acts by stimulating newly described, vasodilatory and antiproliferative Mas-receptors. Furthermore, AngII itself has also vasodilatory and antiproliferative properties via angiotensin type 2 receptors (AT2R). We and others have described different components of RAS in various parts of the eye. It can be suggested that these components play a role in regulation of IOP either by reducing aqueous humour formation or by increasing its outflow or both.