Abstract
Purpose :
As a protrusion from the brain, the retina might serve as a patient-friendly source of biomarkers reflecting neurodegeneration. Previous research showed thinning of total macular and peripapillary retinal nerve fiber layer (RNFL) thickness measured with OCT in patients with Alzheimer’s Disease (AD) compared to controls. This observational pilot aimed to i. determine retinal thickness with Spectral Domain OCT (SD-OCT) in amyloid positive, early onset AD (EOAD) patients and controls, and ii. to correlate retinal thickness to cortical atrophy scores on MRI as established AD biomarkers.
Methods :
Fifteen subjects with AD and 15 controls from the Amsterdam Dementia Cohort (age<70y, Mini-Mental State Examination(MMSE)>16) were included. All patients met NIA-AA criteria and were amyloid positive in CSF and/or on amyloid-PET. Controls were amyloid negative subjects with subjective cognitive decline (SCD). Subjects underwent a complete ophthalmological and neurological examination including MRI and SD-OCT of the macula and optic disk (Heidelberg, Spectralis). Patients were excluded for glaucoma. Peripapillary RNFL and total macular thickness were measured and correlated with visual cortical atrophy scores on MRI: medial temporal lobe atrophy (MTA), global cortical atrophy (GCA) and parietal cortical atrophy (PCA).
Results :
Peripapillary RNFL thickness was 95.9μm±9.0 for AD patients versus 97.5μm±6.96 for controls (t-test, p=0.575). Total macular thickness (mean of inner ring and outer ring of ETDRS grid) was 316.1μm±11.0 for AD patients versus 320.5μm±7.5 for controls (t-test, p=0.216). Total macular thickness was significantly correlated (after Bonferroni, α<0.017) with PCA (Spearman’s rho= -0.603, p=0.001) but not with GCA (Spearman’s rho= -0.443, p=0.018) and MTA (Spearman’s rho= -0.286, p=0.140) in the total study group(figure 1).
Conclusions :
Peripapillary RNFL and total macular thickness were not significantly decreased in an amyloid positive EOAD cohort without glaucoma compared to controls. Total macular thickness was significantly correlated to PCA on MRI, supporting the hypothesis that neurodegenerative diseases may be reflected by retinal changes. Future research in larger cohorts with established AD biomarkers are needed to asses the diagnostic value of retinal thickness for AD diagnosis.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.