Abstract
Letrozole is an oral aromatase inhibitor used in the treatment of hormone receptor-positive breast cancers in postmenopausal women. It acts by inhibiting the conversion of androgens to estrogen thereby lowering the estrogen synthesis in the body. We report a case of bilateral cystoid macular edema (CME) in a postmenopausal woman on letrozole for breast cancer. A 62-year-old female presented with painless gradually progressive bilateral diminution of vision for the past 6 months. Her previous ocular history is unremarkable. Her medical history is known for carcinoma of the breast for which she underwent chemotherapy followed by mastectomy, adjuvant hormonal therapy, and radiotherapy. The patient had been on letrozole for the past 4½ years. At presentation, the best corrected visual acuity in the right eye was 0.4 and 0.5 in the left eye. Fundus examination revealed significant bilateral CME. Optical coherence tomography and fundus fluorescein angiography confirmed the diagnosis. After discussing the possibility of letrozole-related maculopathy with the treating oncologist, letrozole was discontinued and the patient was reassessed. Reduction of macular edema and mild visual improvement was observed when letrozole was subsequently stopped. Although ocular side effects are rare with letrozole, a comprehensive ophthalmic evaluation is recommended for patients who present with visual disturbances for prompt intervention.