PURPOSE: To probe into the effects of malnutrition-sarcopenia syndrome on the changes of retinal and choroidal microvasculature. METHODS: To achieve our goals, we employed optical coherence tomography angiography (OCTA), a cutting-edge non-invasive imaging technique, to compare retinal and choroidal parameters in a controlled setting. A total of 22 participants diagnosed with Malnutrition-Sarcopenia Syndrome were enrolled alongside 22 healthy subjects matched for age and gender as controls. Parameters under scrutiny included inner retinal vessel flow density (VFD), total retinal thickness, and choroidal thickness, choroidal vascularity index (CVI). Linear regression analyses were performed to identify any significant variations of systemic profles associated with retinal and choroidal parameters. RESULTS: Our data unveiled substantial discrepancies in the retinochoroidal microvascular health between the patient cohort and the control group. Specifically, the patients with malnutrition-sarcopenia syndrome showcased notably diminished values in inner retinal VFD, total retinal thickness, choroidal thickness and CVI, all with extreme statistical significance (p <
0.0001). Further, body mass index (BMI) exhibited a noteworthy positive association with retinal thickness (p = 0.026), whereas skeletal muscle index (SMI) showed a similar trend with choroidal thickness and CVI through both univariate and multiple linear regression analyses. Besides, pearson's correlation analysis also indicated that SMI was positively correlated with choroidal thickness and CVI in the sarcopenia patients. CONCLUSIONS: The collective evidence suggests that malnutrition coupled with sarcopenia exerts deleterious effects on chorioretinal microvasculature, with potential repercussions on visual function. This research underscores the imperative of proactive monitoring and early intervention targeting chorioretinal microvasculature changes in patients battling malnutrition-sarcopenia syndrome.