Choriocapillaris Flow Deficits Analysis as Biomarker in Early Alzheimer’s stages

Abstract

Purpose : To assess the role of choriocapillaris flow deficits (CCFD) using optical coherence tomography angiography (OCTA) as a potential biomarker for early diagnosis of Alzheimer’s disease without cognitive impairment.

Methods : Early Alzheimer’s disease subjects with a mean (SD) age of 82.2 (6.1) had pathologic cerebrospinal fluid (CSF) Abeta42 /Tau (PATs) of ≤ 2.7 were compared with age-matched subjects with normal CSF Abeta42/Tau (NATs; mean (SD) age 74.3 (10.6) p=0.07). Both eyes of each subject were imaged using a swept-source (SS)-OCTA device (Zeiss Plex Elite 9000; 6x6 mm; 1024x1024 pixels, (foveal centered). One eye per subject was included in the analysis and if both eyes were eligible the right eye was chosen. To compute the CCFD%, a 16-um thick en face slab was generated with the inner boundary positioned 4 microns below the automatically segmented Bruch’s membrane. These CC OCTA slabs were binarized using Image J and the CCFD% was computed using a Phansalkar local threshold with a radius of ~ 20 um. Superficial large vessels were masked. CCFD% were assessed within the whole slab, and within the 3-mm and 6-mm rings of the ETDRS grid. Mean measurements of CCFD% in PATs were compared to CCFD% in aging subjects with normal CSF Abeta42/Tau (NATs).

Results : A total of 23 eyes were included in this analysis (13 PATs, 46.1%). CCFD% (mean (SD)%) measured within the whole 6x6 mm slab in eyes of PATs were significantly higher (11.25 (6.9) %) compared to the CCFD% in the NATs (6.53 (0.97) %); p=0.032. In the sub-analysis, this relationship was confirmed with PATs having greater CCFD% within both the 3-mm and the 6-mm ETDRS circles (12.60 (7.9) % and 10.46 (5.9) %, respectively) compared to the NATs (7.76 (1.6) % and 6.54 (1.0) %, respectively), with p-values <0.05. (Table 1)

Conclusions : The increased CCFD% in eyes with a pathological CSF Aβ42/Tau ratio may suggest an early involvement of the choriocapillaris in subjects with pre-Alzheimer disease. The CCFD% could prove to be a useful screening parameter to detect early onset of the disease before more severe cognitive deterioration.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Choriocapillaris Flow Deficits Analysis within the whole slab, 3-mm and 6-mm ETDRS circles in subjects with Early Alzheimer’s Disease.