Abstract
Purpose :
To evaluate retinal microvasculature and neurodegenerative alterations in patients with Alzheimer’s disease (AD) and Mild Cognitive Impairment (MCI) compared to controls using optical coherence tomography angiography (OCTA).
Methods :
In this prospective study (Clinicaltrials.gov NCT03233646), subjects with AD or MCI aged ≥50 years, along with age and gender matched controls, were imaged using OCTA (Angioplex, Carl Zeiss Meditec, Dublin, CA) at the Duke Memory Disorders Clinic. Exclusion criteria included a history of non-AD associated dementia, diabetes mellitus, uncontrolled hypertension, demyelinating disorders, glaucoma, macular degeneration, other retinal pathology interfering with OCTA analysis, or corrected visual acuity of <20/40. All subjects underwent a Mini Mental State Examination (MMSE) to evaluate cognitive function. For each subject, one eye (the one with the highest quality scan quality, minimum 7/10) was analyzed for vessel density (VD) and perfusion density (PD) in the central 3mm of the superficial capillary plexus (SCP, 3x3mm scan), central macular thickness (CMT), ganglion cell layer (GCL) thickness, and retinal nerve fiber layer (RNFL) thickness. Analysis was automated using AngioPlex Metrix software (Carl Zeiss Meditec).
Results :
We enrolled 19 subjects with AD, 21 with MCI, and 82 age and gender matched controls (p>0.05). AD subjects had significantly decreased macular VD and PD in the central 3mm ETDRS grid when compared to controls (p<0.01). AD subjects also had significantly reduced macular VD and PD (p<0.005) when compared to MCI subjects. AD subjects had significantly decreased CMT (p=0.01) and GCL thickness (p<0.005) when compared to controls, while RNFL thickness was not significantly different. Although there was a trend towards a lower VD and PD, along with a thinner GCL in MCI compared to controls, the difference was not significant (Table). MMSE score correlated significantly with both VD and PD (p<0.0001), CMT (p=0.008), and GCL (p<0.001).
Conclusions :
AD subjects had significantly reduced macular VD and PD when compared to both MCI and control subjects. Changes in the retinal microvasculature and GCL correlate with MMSE and may mirror small vessel cerebrovascular and neurodegenerative changes in AD. These parameters may serve as surrogate non-invasive biomarkers in diagnosing AD and monitoring progression of MCI to AD.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.