An object of the present invention is to find an effective treatment for glaucoma and provide it as a pharmaceutical. Combinations of the invention, in particular 2-propanyl 4-{(3S, 5aR, 6R, 7R, 8aS)-6-[(1E, 3R)-4-(2,5-difluorophenoxy)-3- The combination of hydroxy-1-buten-1-yl]-7-hydroxyoctahydro-2H-cyclopenta[b]oxepin-3-yl}butanoate and a β-blocking drug is obtained when each drug is administered as a single drug. Compared with, since it has the effect of enhancing the intraocular pressure-lowering action and sustaining the intraocular pressure-lowering action, it is useful as a glaucoma therapeutic agent.본 발명은, 유효한 녹내장 치료법을 발견하여, 의약품으로서 제공하는 것을 목적으로 한다. 본 발명의 조합, 특히 2-프로파닐 4-{(3S, 5aR, 6R, 7R, 8aS)-6-[(1E, 3R)-4-(2,5-디플루오로페녹시)-3-히드록시-1-부텐-1-일]-7-히드록시옥타히드로-2H-시클로펜타[b]옥세핀-3-일}부타노에이트와 β 차단약의 조합은, 각 약제의 단제 투여시와 비교하여, 안압 하강 작용을 증강시키고, 또한 안압 하강 작용을 지속시키는 효과를 갖기 때문에, 녹내장 치료제로서 유용하다.