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

Abstract

PurposeAlzheimer's disease (AD) is a progressive neurodegeneration in which vascular changes occur that constitute cerebral amyloid angiopathy. Recently, alterations and deposits have been discovered in the retinas and choroids of patients with AD that correlate with the evolution of the disease. The development of new techniques for the study of ocular vascularization, Laguna ONhE and Angio‐optical coherence tomography (OCTA), non‐invasive and non‐contrast tests, allow us to study ocular vascular alterations caused by AD.MethodsSeventeen patients with mild AD (mAD) and 49 healthy controls, all without ophthalmological diseases after a complete eye examination, were studied for haemoglobin (Hb) coefficient in the optic nerve head by Laguna ONhE, as well as choroid thickness and foveal avascular zone (FAZ) of the retina by OCTA. For statistical analysis, the Mann‐Whitney test was applied with the SPSS 22.00 program.ResultsThe Mini Mental State Examination of the mAD patients was 24.00 ± 5.32, while the control group was 29.40 ± 1.83, being the difference significant (p < 0.001) between them. Comparing both group, no significant difference was found in the Hb coefficient of the optic nerve head, although in the papillomacular bundle, there was a slight increase of Hb coefficient in mAD patients. A significant (p < 0.05) thinning of the choroid was found in the mAD patients, while the FAZ was unchanged in comparison to control.ConclusionsIn patients with mAD, a significant decrease in the choroidal vascular network was observed, while the retinal network and the Hb of the optic nerve head did not yet show any changes in mild stages of AD. These results show the choroidal changes as an early biomarker of amyloid angiopathy that could be used for the diagnosis and follow‐up of AD.