Choroidal changes as a biomarker of cerebral amyloid angiopathy in mild Alzheimer's disease patients.

Abstract

Purpose : Alzheimer's disease (AD) is a progressive neurodegeneration in which cerebral amyloid angiopathy develops, resulting in vascular changes. In recent works, alterations and deposits in the choroids and retinas of patients with AD have been observed that correlate with the disease's progression. Novel techniques for the study of ocular vascularization, such as the Laguna ONhE and the angio-optical coherence tomography (OCTA), tests that can be performed in these patients (non-invasive and without contrast), will allow the study of ocular vascular changes caused by AD

Methods : Seventeen patients with mild AD (mAD) and 49 healthy controls, which after a complete eye examination did not present any ophthalmological diseases, were studied for the coefficient of hemoglobin (Hb) in in the optic nerve head by Laguna ONhE, and for thickness of the choroid and foveal avascular zone (FAZ) of the retina by the OCTA. For the statistical study, the Mann-Whitney test was used.

Results : The Mini Mental State Examination of the mAD patients was 24.00±5.32, while the control group was 29.40±1.83, with a significant difference (p<0.001) between them. In the Hb coefficient of the optic nerve head there was no significant difference when comparing both groups, although in the papillomacular bundle there was a slight increase in the Hb coefficient in mAD patients. However compared to the control, the choroid in the mAD patients showed a significant thinning (p<0.05), while the FAZ did not change.

Conclusions : In patients with mAD, a significant decrease in the choroidal vascular system was found, while the retinal system and the Hb of the optic nerve head did not exhibit any changes in the mild stages of AD. These results are showing that choroidal changes potentially could be an early biomarker of amyloid angiopathy which may be used for the diagnosis and follow-up of AD.

This is a 2021 ARVO Annual Meeting abstract.

 

Measurement of the choroidal thickness and Foveal Avascular Zone (FAZ). (A) SD-OCT analysis of choroidal thickness: (A1) retinal zone analyzed; (A2) choroidal thickness quantification (μm). (B) OCTA analysis of the FAZ; (B1) superficial capillary plexus; (B2) deep capillary plexus.

 

Colorimetric percentage differences of hemoglobin in the optic nerve head, analyzed using photographs of the optic nerve with Laguna ONhE program, between mild AD and control groups. Blue tones: decreased hemoglobin. Red tones: increased hemoglobin.