Treatment of ophthalmic disease largely involves the administration of topical medication in doses that would appear small relative to those used systemically. With a few exceptions (such as β receptor antagonists) the systemic side effects of topical ocular medication, though recognised, are often ignored in clinical practice. We report a case that highlights the need for constant vigilance in the context of such ophthalmic therapy. A 66 year old white man, on treatment with topical latanoprost for primary open angle glaucoma, required further reduction of intraocular pressure, in the pursuit of which topical brinzolamide was added to one eye only. At review 3 months later, the patient reported having …