BACKGROUND: competitive antagonism on the same adrenergic receptor when used simultaneously. There is the aggravation that β-blockers can precipitate bronchospasm.: Determine prevalence of potential interaction between bronchodilators to treat chronic obstructive OBJETIVE pulmonary disease (COPD) or asthma and topical β-blockers for glaucoma.: Cross-sectional study on prescribing topical β-METHODS blockers for glaucoma in patients older than 40 years who were receiving inhaled bronchodilators for COPD or