To report a case of bilateral branch retinal vein occlusion development after taking long-term tamoxifen adjuvant therapy.

A 72-year-old female breast cancer patient with a 10-year history of tamoxifen intake presented with decreased visual acuity that began 5 years prior. The patient had no other past history. The best corrected visual acuity (BCVA) was 0.3 in the right eye and 0.04 in the left eye. There was no specific finding of anterior segment on slit lamp examination. On fundus examination, sheathed branch retinal veins were observed in the inferotemporal area of the right eye and superotemporal and inferotemporal areas of the left eye. Microangiopathies were observed around the occluded branch retinal veins in both eyes and macular edema was present in the left eye. Laser photocoagulation was performed at the non-perfusion area in both eyes and an intravitreal injection of bevacizumab and 3 intravitreal injections of triamcinolone were administered into the left eye. The BCVA did not change after 3 years and remained relatively stable.

If a patient presents with decreased visual acuity after taking tamoxifen, fundus examination and fluorescein angiogram should be performed due to the possibility of branch retinal vein occlusion.