Kowa Company Ltd. has been developing "Ripasudil Hydrochloride Hydrate", a Rho kinase inhibitor, for the indication of corneal endothelial diseases (Developmental code: K-321). Company have recently submitted an IND (Investigational New Drug) application to the U.S. FDA (Food and Drug Administration) on 30 August 2019 in order to commence a Phase 2 clinical study (hereinafter referred to as "this study") in the U.S. This substance was launched in December 2014 in Japan (Brand name: GLANATEC® ophthalmic solution 0.4%) as the world's first glaucoma drug with Rho kinase inhibitory activity, and it was approved in February 2019 in Korea. It has been suggested that this substance may affect kinases in the eye, and Kowa has been considering the possibility not only of glaucoma but also of other ophthalmic diseases. In this study, will investigate the efficacy and safety in patients with corneal endothelial diseases. GLANATEC® Ophthalmic Solution 0.4% includes this substance, which was licensed from D. Western Therapeutics Institute (DWTI) to Kowa, as an active ingredient, and lowers intraocular pressure by promoting discharge of aqueous humor through a main outflow via trabecular meshwork-Schlemm canal as a result of Rho kinase inhibition. In clinical studies enrolling patients with primary open-angle glaucoma and ocular hypertension in Japan, GLANATEC® Ophthalmic Solution 0.4% has been demonstrated to be effective in lowering intraocular pressure in both cases of mono-therapy and conjunctival therapy along with conventional treatment-glaucoma and ocular hypertension drugs.