A nurse is reinforcing teaching with a client who has primary open-angle glaucoma and a new prescription for timolol eye drops. Which of the following statements indicates an understanding of the teaching?

A. “This medication will darken the color of my eyes.” is incorrect. Timolol is a nonselective beta-blocker used to reduce intraocular pressure in glaucoma. It does not typically cause eye color changes. B. "I should check my heart rate while taking this medication." is correct. Timolol can cause systemic side effects such as bradycardia, so the client should monitor their heart rate while taking the medication. C. "I should take a zinc supplement while taking this medication." is incorrect. Zinc supplementation is not related to the use of timolol. D. “This medication will dilate my eyes." is incorrect. Timolol works by decreasing aqueous humor production, reducing intraocular pressure, and does not cause dilation of the eyes. Medications like atropine are used for pupil dilation.