To the Editor. —Betoptic (betaxolol hydrochloride) is a cardioselective β-adrenergic receptor blocking agent recently released in the United States for ophthalmic use in the control of glaucoma. The package insert states that "ophthalmic betaxolol has minimal effect on pulmonary and cardiovascular parameters."1 It is further stated in the insert that "Betoptic® ophthalmic solution has had little or no effect on heart rate or blood pressure in clinical studies" but that "caution should be observed in treating patients with a history of cardiac failure." We herein report a case of a patient with well-compensated sick-sinus syndrome who experienced decompensation with the use of Betoptic. Report of a Case. —An 80-year-old man with long-standing chronic open angle glaucoma was seen, with the following ocular findings: intraocular tensions of persistently 20 to 25 mm Hg, cup-to-disc ratios of 0.85 in each eye, and visual fields that showed dense superior arcuate defects in each