To provide a drug therapy for preventing glaucoma or for preventing or treating ocular hypertension, in which the ocular hypotensive effect is strong and the effect is more durable.SOLUTION: The invention provides a combination for preventing or treating glaucoma, the composition being obtained by combining (S)-(-)-1-(4-fluoro-5-isoquinoline sulfonyl)-2-methyl-1,4-homopiperazine or a salt or solvate thereof, and a prostaglandin.SELECTED DRAWING: None【課題】眼圧下降作用が強力で且つその持続時間が延長された、緑内障予防若しくは高眼圧症の予防又は治療するための薬物療法の提供。【解決手段】緑内障予防又は治療のための、（Ｓ）－（－）－１－（４－フルオロ－５－イソキノリンスルホニル）－２－メチル－１，４－ホモピペラジン若しくはその塩又はそれらの溶媒和物とプロスタグランジン類との組み合わせ。【選択図】なし
