Timolol, also known as timolol, is a white crystalline powder. Timolol belongs to beta-blocker. It is used to treat angina pectoris, hypertension, glaucoma, tachycardia and other diseases. Contraindications are: 1. contraindicated in cardiac insufficiency. 2. contraindicated in sinus bradycardia. 3. contraindicated in atrioventricular block. 4. contraindicated in asthma. This drug has a rapid onset of action and relatively few adverse effects. It has no effect on pupil size, reaction to light, or vision. In addition, this drug needs to be kept under light and sealed.