Timolol eye drops belong to a kind of IOP-lowering drug, which belongs to adrenergic receptor blocker from the classification of the drug. The principle of the drug is that by inhibiting the production of atrial aqueous humor, thus reducing IOP, but the magnitude of this drug to reduce IOP is limited, generally within 5mmHg, and the effect will be weakened by long-term use, so if there is a disease like glaucoma, especially closed-angle glaucoma, you can choose to use this drug to control IOP. However, because this drug is a beta-blocker, it is contraindicated for systemic diseases. If there is atrioventricular block, sinus node lesion, bronchial asthma and other conditions, it is a contraindication to the drug, and such patients are not allowed to choose this drug.