Abstract
Purpose :
As a protrusion from the brain, the retina might reflect neurodegenerative diseases. There is increasing evidence of changing retinal vasculature and retinal nerve fiber layer (RNFL) thickness in AD patients. This study evaluated these ophthalmological parameters for their potential as early and easily assessable biomarkers for AD.
Methods :
The potential of retinal vasculature and RNFL as biomarkers for early AD was studied in a cohort of cognitively healthy elderly persons, that will be followed over time. Dynamic amyloid PET scans were acquired using [18F]Flutemetamol, to assess amyloid-beta non-displaceable binding potential (Aβ BPND) in the posterior cingulate. MRI scans were acquired to assess hippocampal volume and intracranial volume. Fundus images of 129 individuals were analyzed and retinal vascular parameters (RVPs), including calibers, tortuosity and fractal dimension, were measured using Singapore I Vessel Assessment (SIVA) software. Peripapillary RNFL thickness of 120 individuals was measured using optical coherence tomography. Firstly, it was investigated whether RVPs are related to Aβ BPND. Secondly, it was investigated whether RNFL thickness is associated with hippocampal volume.
Results :
Retinal venular changes were associated with Aβ BPND, after adjusting for age, gender and cardiovascular risk factors. Higher Aβ BPND was associated with a smaller central retinal vein equivalent (β=0.004, p=0.049), a higher venular branching coefficient (β=0.342, p=0.024), and a higher venular asymmetry factor (β=0.590, p=0.014). Additionally, a thinner RNFL in the superior (β=8.60, p=0.002) and temporal superior (β=5.62, p=0.005) segment was associated with smaller hippocampal volume, after adjusting for age, gender and intracranial volume.
Conclusions :
Cognitively healthy individuals with retinal venular changes and thinner RNFL show higher cerebral Aβ BPND in the posterior cingulate and decreased hippocampal volume respectively, suggesting these characteristics are potential biomarkers for early AD. Future follow-up studies will reveal their true value.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.