Distinct ocular microvascular alterations in Alzheimer's disease and cerebral small vessel disease.

INTRODUCTION

While both Alzheimer's disease (AD) and cerebral small vessel disease (CSVD) involve vascular dysfunction, the ocular microvascular differences between them remain largely underinvestigated.

METHODS

This cross-sectional study included 650 participants (149 AD, 276 CSVD, and 225 cognitively unimpaired individuals). Optical coherence tomography angiography (OCTA) metrics were analyzed to characterize ocular microvascular alterations.

RESULTS

CSVD patients exhibited a higher burden of retinal ischemic perivascular lesions (RIPLs) than AD patients (all p < 0.05), whereas AD patients showed reduced choriocapillaris (CC) density (p = 0.031). In the CSVD group, RIPLs were associated with total CSVD score (p = 0.049), while reduced CC density was associated with elevated phosphorylated tau 181 in the AD group (p = 0.001). Machine learning models integrating OCTA metrics effectively differentiated AD from CSVD (area under the curve = 0.86).

DISCUSSION: AD and CSVD exhibit distinct ocular microvascular alterations, supporting OCTA-derived measures as potential non-invasive biomarkers.

TRIAL REGISTRATION NUMBER: ChiCTR2000041386.