Assessment of retinal vascular network in amnestic mild cognitive impairment by optical coherence tomography angiography

Abstract

Objective: To assess the presence of retinal vascular network abnormalities in amnestic mild cognitive impairment (aMCI) patients and healthy subjects (HS) through optical coherence tomography angiography (OCTA).

Methods: OCTA and SD-OCT were performed in aMCI patients and cognitive normal HS. A complete neuropsychological evaluation was performed. Differences in vessel density (VD) in each retinal vascular plexus and in foveal avascular zone (FAZ) were evaluated with linear mixed model after correction for age, sex and disease duration.

Results: Twenty-seven aMCI patients (10 Single domain aMCI, 17 Multidomain aMCI) and 29 HS were enrolled. aMCI patients showed a statistically significant reduced VD in superficial capillary plexus (SCP), deep capillary plexus (DCP) and an increased FAZ compared to controls. When aMCI patients were divided in single domain (SD) and multiple domains (MD) aMCI, SD aMCI showed no VD differences in SCP, DCP and Radial Peripapillary Capillary, while the FAZ area was significantly larger compared to controls. In MD aMCI, VD values were lower and FAZ was increased compared to controls. Comparing both aMCI groups, MD aMCI showed a significant reduction in VD values of SCP. No correlation was found between mini mental state examination (MMSE) scores and OCTA parameters.

Conclusions: OCTA is able to detect changes in retinal microvascular network in early cognitive deficits and, the most sensitive alteration seems to be the enlargement of the FAZ. This non-invasive tool provides useful information on retinal involvement patterns in MCI diagnosis and follow up. Vascular network impairment seems to be related to the number of domains affected and not to MMSE.

Fig 1

Optical coherence tomography (SD-OCT) images of the ganglion cell complex (GCC) and retinal nerve fiber layer (RNFL) in a control subject (male, 72 years) (A, B), in a patient with Single Domain amnestic Mild Cognitive Impairment (SD aMCI) (male, 70 years) (A1, B1) and in a patient with Multiple Domain aMCI (male, 73 years) (MD aMCI) (A2, B2). Compared with healthy control, SD aMCI patient showed no differences in GCC (A1) and RNFL (B1) while GCC (A2) and RNFL (B2) were significantly thinner in MD aMCI patient.

Fig 2

Optical coherence tomography angiography (OCTA) images of the retinal microvascular network and the foveal avascular zone in a control subject (male, 72 years) (A, B, C, D), in a patient with Single Domain amnestic Mild Cognitive Impairment (SD aMCI) (male, 70 years) (A1, B1, C1, D1) and in a patient with Multiple Domain aMCI (male, 73 years) (MD aMCI) (A2, B2, C2, D2). Compared with healthy control, the SD aMCI patient showed no differences in vessel density of superficial capillary plexus (SCP) (A1), deep capillary plexus (DCP) (B1), radial peripapillary capillary (RPC) (C1) and a significant enlargement of foveal avascular zone (FAZ) area (D1). A statistically significant reduction in vessel density of the SCP, DCP, RPC (A2, B2, C2) and a significant enlargement of FAZ area (D2) were found in the MD aMCI patient.