MEK Inhibitor-Associated Retinopathy Secondary to the Use of Trametinib

Introduction: Mitogen-activated protein kinase (MEK) inhibitors have become an important component in the treatment of patients with BRAF-mutated cancers. Although generally well tolerated, these therapies have been associated with a range of ocular adverse effects. As the use of targeted oncologic therapies continues to increase, eye care providers should be familiar with these potential complications. Case Report: A 74-year-old Caucasian female with stage IVB BRAF V600E-mutated anaplastic thyroid carcinoma presented with new-onset flashes and persistent floaters in the left eye after six weeks of treatment with trametinib and dabrafenib as part of a clinical trial, along with adjuvant radiation therapy. Dilated fundus exam and multimodal retinal imaging demonstrated bilateral peripheral retinal hemorrhages, greater in the right eye, subretinal fluid involving the right fovea, and an acute posterior vitreous detachment in the left eye without associated retinal tears or detachment. The patient was instructed to monitor for visual changes and return for follow-up in six weeks. At this follow-up visit, OCT demonstrated complete resolution of the subretinal fluid, and the peripheral retinal hemorrhages had nearly resolved, with only faint residual hemorrhages remaining in the right eye. Conclusion: This case demonstrates the importance of considering treatment-related ocular findings in patients receiving targeted cancer therapies. Prompt recognition, multimodal retinal imaging, and communication between eye care providers and oncology teams are necessary for identifying medication-related toxicity and supporting preservation of vision and continuation of effective systemic therapy.