Retinal Microvasculature Parameters with Optical Coherence Tomography Angiography and Mean Ocular Perfusion Pressure Changes in Mild Cognitive Impairment and Alzheimer’s Disease

Background To explore the ocular vascular variation involvement in mild cognitive impairment (MCI) and Alzheimer’s disease (AD) cohorts. The measurement of the retinal vessel density was performed by spectral-domain optical coherence tomography angiography (OCTA). Methods This study including 24 eyes of normal cognitively individuals (NC group), 23 eyes of MCI patients (MCI group) and 11 eyes of AD patients (AD group) measured retinal vessel density with OCTA. Mean arterial pressure (MAP) and mean ocular perfusion pressure (MOPP) were calculated based on systemic blood pressure and intraocular pressure. We estimated the association between systemic and ocular vascular elements with cognitive assessment test (Mini-Mental Status Examination, MMSE) result by Pearson’s correlation and linear regression model test. Results The retinal microvascular density were significantly lower in AD group compared to NC group while foveal avascular zone(FAZ) area were larger in AD group versus NC group. Both FAZ and vascular density parameters showed significant correlation with MMSE. After multivariate linear regression analysis, only FAZ and outer ring of optic nerve head were significantly associated MMSE. There was significant difference among three groups in MAP value while it was MOPP was found significant correlation with MMSE. Conclusion The OCTA parameters showed statistic difference between AD group and NC group. While only FAZ and outer ring of optic nerve head were significantly associated with estimated MMSE in multivariate linear regression analysis. So FAZ and outer ring of optic nerve head might be regarded as potential indicators for representing early sign of preclinical stage of AD.