Abstract
Purpose :
Cerebrovascular abnormalities contribute to dementia. Assessing the integrity of the cerebral vasculature in vivo is, however, challenging. OCTA imaging presents a rapid non-invasive method for imaging retinal capillaries, which share many features with brain vasculature. We investigated the association between retinal capillary morphometry and clinical measures of cognitive function to evaluate the potential utility of OCTA capillary metrics as surrogate measures of cerebrovascular health.
Methods :
The capillary networks of 3*3 mm2 parafoveal retinal images acquired in 65 subjects with Spectral-Domain OCTA were examined. A previously validated software was used to analyze the vessel skeleton density (VSD) - the ratio of skeletonized vessel length per unit area. The primary analyses investigated the association between OCTA-VSD and clinical measures of cognitive status – the Clinical Dementia Rating sum of boxes (CDR-SB) and Montreal Cognitive Assessment scores (MoCA). The odds of a subject having a CDR-SB>0, at various levels of VSD classifications were calculated, and the correlation between VSD and MoCA was assessed adjusting for the effects of covariates.
The secondary analyses assessed the relation between VSD and MRI measures of cerebrovascular function: cerebral blood flow (CBF) and blood brain barrier (BBB) integrity assessed as water exchange rate (Kw).
Results :
Results: Subjects’ status ranged from normal to probable dementia (CDR-SB = 0 - 2 [with a median of 0.5]). There was a significant association between retinal OCTA-VSD and CDR-SB, with higher VSD measures corresponding to lower odds of having probable dementia. Specifically, subjects in the lower VSD tertile were 4 times (p=0.04) more likely to have CDR scores greater than 0 than subjects in the middle and upper VSD tertiles. Similarly, VSD decreased with decreasing cognitive function assessed with MoCA (r=0.36, p=0.03).
Furthermore, VSD showed increasing trend with higher CBF and potency of the BBB.
Conclusions :
We found reduced cognitive function to be associated with altered vascular perfusion of the retina. OCTA imaging of the retinal capillaries may provide a viable methodology for investigating capillary alterations, which contribute to cognitive impairment and dementia (VCID), in ways that can complement cerebrovascular assessment.
This is a 2020 ARVO Annual Meeting abstract.