Provided is a pharmacotherapy for preventing glaucoma or preventing or treating ocular hypertension which has potent and immediate intraocular pressure lowering action and exhibits prolonged duration of the action. A combination of (S)-(-)-1-(4-fluoro-5-isoquinolinesulfonyl)-2-methyl-1,4-homopiperazine, a salt thereof or a solvate thereof with an a2 stimulating agent for preventing or treating glaucoma.
