Described here are systems and methods for accessing Schlemm's canal and for delivering an ocular device or fluid composition therein. The ocular devices may maintain the patency of Schlemm's canal without substantially interfering with transmural fluid flow across the canal. The fluid composition may be a viscoelastic fluid that is delivered into the canal to facilitate drainage of aqueous humor by disrupting the canal and surrounding trabeculocanalicular tissues. Tools for disrupting these tissues and minimally invasive methods for treating medical conditions associated with elevated intraocular pressure, including glaucoma, are also described.