BackgroundMetastatic choroidal tumors are hematogenous intraocular metastases of malignant tumors in systemic organs; however, the details of choroidal circulation and morphological changes in the choroid are unknown. The aim of this study is to present a case of metastatic choroidal tumor and examine laser speckle flowgraphy (LSFG)-based choroidal circulation and central choroidal thickness (CCT) before and after chemoradiotherapy.Case presentationA 66-year-old woman with a medical history of breast cancer 16 years ago was referred to our department struggling with blurred vision in her right eye. At the time of initial examination, her best-corrected visual acuity (BCVA) was 0.4 oculus dexter (OD) and 0.9 oculus sinister. Fundus revealed a yellowish-white choroidal elevated lesion measuring 8 papillary diameters with serous retinal detachment (SRD) in the posterior pole. Fluorescein angiography showed diffuse hyperfluorescence and fluorescent leakage due to SRD, and indocyanine green angiography demonstrated no abnormalities in the macula but hypofluorescence in the center of the tumor. Based on these clinical findings, she was diagnosed with metastatic choroidal tumor. After chemoradiotherapy, the metastatic choroidal tumor became scarred, and SRD disappeared. The rate of changes in macular blood flows assessed by mean blur rate on LSFG and CCT of her right eye were 33.8 and 32.8% decrease at 5 months after the initial visit, respectively. BCVA was 0.5 OD 27 months after the initial examination.ConclusionChemoradiotherapy resulted in regression of the metastatic choroidal tumor and disappearance of SRD, with a decrease in central choroidal blood flow and CCT. The choroidal blood flow on LSFG could reflect an increased oxygen demand by cancer cells invading the choroid and substantial blood supply.