Headaches related to latanoprost in open-angle glaucoma

Clinical relevance: The existing notion that topical latanoprost can lead to symptoms of headaches by reporting three cases of headache symptoms that developed following instillation of latanoprost prescribed as first-line therapy for newly diagnosed primary open-angle glaucoma (POAG) is explored in this case series.Background: Prostaglandin analogues (PGAs) are often used as first-line treatment in the treatment of POAG. An uncommon and infrequently reported side effect of PGAs is headaches.Methods: A retrospective review of patient records was conducted on patients seen at the Centre for Eye Health between April 2016 and August 2017. Clinical findings, including outcomes following interventions such a punctal occlusion, as well as the proposed pharmacological mechanism underlying this phenomenon are presented and discussed.Results: Case 1 is a 62-year-old Caucasian male diagnosed with POAG and prescribed latanoprost in both eyes. At the follow-up visit, he reported waking up in with a dull throbbing headache following instillation of the eye drops the night before. Case 2 is a 58-year-old Asian male with POAG prescribed latanoprost to both eyes. Within a week, he developed symptoms of recurrent progressively worsening headaches post-instillation which persisted into the morning. Case 3 is a 75-year-old Caucasian male with POAG prescribed latanoprost for both eyes. He developed latanoprost sensitivity as well as headache symptoms associated with the eye drops which resolved followed its cessation. All patients reported initial symptoms of headaches associated with latanoprost use however the headaches were not persistent with intermittent punctal occlusion (cases 1 and 2) or intra-class drug rechallenge (case 3).Conclusion: Although there may be a yet-undiscovered link between a headache response and latanoprost, these cases call to question the pharmacological relationship between latanoprost and headache symptoms. A systemic approach to critically examine the pathophysiological link between pharmacological therapy and potential adverse effects is proposed.