Unilateral Tamoxifen-Induced Retinopathy as a Consequence of Breast Cancer Treatment-Multimodal Imaging Value

Tamoxifen is a drug used in breast cancer therapy, which inhibits the division of neoplastic cells targeting estrogen receptors. The drug is generally well-tolerated and its use does not cause serious side-effects. The standard dose of the drug is 20 mg once a day for 3 to 5 years. Available epidemiological data have shown that the incidence of ocular toxicity of tamoxifen ranges between 0.9% and 12.0% and increases with higher tamoxifen dose. A rare known complication of tamoxifen use is the development of retinopathy. We present a case of 57-year-old woman presented to an ophthalmologist with decreased visual acuity in her right eye. She has been treated with tamoxifen 20 mg daily for 7 years for breast cancer. Clinical examination and multimodal imaging methods help confirm the diagnosis of unilateral tamoxifen associated retinopathy (TAR). Optical coherence tomography angiography (OCTA) was crucial in the diagnostic process and differential diagnosis, especially in differentiating it from type 2 macular telangiectasias. The correct diagnosis of TAR is very important in deciding the treatment option of tamoxifen. Based on our diagnosis, the oncologist recommended another course of treatment. Tamoxifen therapy was discontinued and switched to letrozole 2.5 mg once a day. The patient attends ophthalmological examination regularly. Visual acuity, OCT and OCTA results remain stable.