The cerebral microvasculature cannot be easily studied non-invasively. Because the
retina and brain share embryological, anatomical and physiological similarities, studies
of retinal blood vessels may prove to be useful as a surrogate marker for cerebrovascular
disease. In epidemiological studies abnormal retinal arteriovenous ratios (AVRs) predict
the risk of stroke and vascular dementia. However, the association between retinal
vasoreactivity, cerebral small vessel ischemic disease, and cerebral blood vessel
function remains unknown.
To examine (1) the association between cerebral ischemic white matter disease (WMD)
and retinal microvessel behavior and (2) the relationship between retinal blood vessel
reactivity and measures of cerebrovascular function.
Cohort study of 12 patients with ischemic WMD and 14 healthy controls. Retinal vasoreactivity
was measured following high frequency flicker light stimulation. Middle cerebral artery
(MCA) vasoreactivity was measured using transcranial Doppler ultrasound (TCD). Magnetic
resonance imaging scans (MRIs) were reviewed for evidence of ischemic WMD.
Patients with ischemic WMD had attenuated retinal venous (2.2%±0.27 SD, vs. controls 6%±0.7 SD, p=0.002, CI 95%) and arterial (1.9%±0.8 SD, vs. controls 4.9%±0.8 SD, p=0.004, CI 95%) vasoreactivity compared to controls. An attenuated retinal venous light
flicker response was associated with a significant decrease of MCA vasoreactivity
(r=0.45, p=0.05, CI 95%). Decreased AVRs, an indicator for altered retinal vessel architecture
in patients with cerebral chronic ischemic WMD, were also significantly correlated
with dysfunction of cerebral vasoreactivity (r=0.69, p=0.001, CI 95%).
In this study functional and structural impairment of the retinal microvasculature
were associated with ischemic WMD and measures of cerebral vascular function. Microvascular
dysfunction in the eye may predict cerebral small vessel disease, but validation by
larger studies is needed.