Fluorescence Lifetime Imaging Ophthalmoscopy in early Alzheimer’s disease

Abstract

Purpose : To investigate Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO) findings in patients with an early stage of Alzheimer’s disease (AD)

Methods : In this prospective, observational study, normal controls and patients with an early stage of AD undergoing Alzheimer’s biomarker analysis at Huntington Medical Research Institute were recruited for this study. Subjects with advanced AD or mild cognitive impairment were excluded. The cohort was divided into control and AD group according to Alzheimer related laboratory findings (β–amyloid(Aβ), total tau in cerebrospinal fluid(CSF), MMSE, Montreal Cognitive Assessment). Risk factor associated data(BMI, hypertension, lipid profile,etc), FLIO-derived parameters(τ_m, τ_1, τ_2, and τ₃ in short and long spectral channels(SSC and LSC)), ganglion cell complex(ggl) thickness in structural optical coherence tomography(OCT;Cirrus HD-OCT model 5000), and OCT angiography(OCTA) data including vascular density of superficial, deep retinal plexus and choriocapillary were compared and correlated between the two groups. Further analyses were explored in phakic and pseudophakic subgroups

Results : A total of 28 eyes from 15 subjects were included in this analysis. 8 subjects were cognitively healthy with normal laboratory findings(control) and 7 subjects were cognitively healthy or slightly impaired with Alzheimer-like Aβ and/or tau levels(AD group). As expected, among the clinical biomarkers, Aβ and tau levels in the CSF were different between the two groups, and ggl thickness was significantly decreased in the AD group(Table 1). In terms of FLIO parameters, τ_m in both spectral channels and τ₁ in SSC_, τ₂ in LSC showed significant difference in phakic subjects(593.9±93.3, 454.4±38.6, 475.0±71.6 and 394.1±28.2 in SSC and LSC of Alzheimer group and control group, respectively, P=0.036 and 0.024). Aβ, tau level in the CSF, and ggl thickness correlated with τ_m in LSC and τ₁ in SSC with phakic subjects but only ggl thickness showed correlation with FLIO parameters in pseudophakic subjects(Table 2)

Conclusions : FLIO-derived parameters appear to correlate with Aβ and tau levels in the CSF and ggl thickness on OCT in AD patients. The ggl thickness showed correlation regardless of lens status, but Aβ and tau levels correlated only in phakic patients. If these findings can be validated in future longitudinal studies, FLIO may prove to be useful as a non-invasive diagnostic tool for Alzheimer’s disease

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.