Provided herein is an ophthalmic formulation that comprises a fine particle of an A1 agonist in an aqueous suspension and a manufacturing process thereof. More specifically, provided herein is a topically applied ophthalmic aqueous suspension which is obtainable by suspending a fine particle of an A1 agonist in a surfactant and preservative a method of reduction of intraocular pressure using the formulation and a manufacturing process of the aqueous suspension thereof.