Evaluation of retinal and choroidal changes in patients with Alzheimer’s type dementia using optical coherence tomography angiography

Abstract

AIM: To evaluate the changes in fundus parameters in patients with Alzheimer’s type dementia (ATD) using optical coherence tomography angiography (OCTA), to record flash electroretinograms (ERG) using the RETeval system and to explore changes in retinal function. METHODS: Twenty-nine patients with ATD and 26 age-matched normal subjects were enrolled. All subjects underwent OCTA scans to analyse the superficial retinal vessel parameters in the macular area, including the vessel length density, the vessel perfusion density and the area of foveal avascular zone (FAZ), as well as the choroidal thickness. The differences between the patients with ATD and the normal control group were compared and explored the relevant factors affecting vessel parameters. We also recorded the flash ERGs using the RETeval system and intended to explore changes in retinal function by analysing the ERG image amplitude in patients with ATD. RESULTS: The vessel parameters [Pvessel length density=0.005 and Pvessel perfusion density=0.006) and average choroid thickness (P<0.001) in the macular area of the ATD group was less than the control group. The FAZ area was statistically significantly enlarged in the ATD group (P<0.001). These parameters were correlated with the Mini-Mental State Examination (MMSE) score and the Montreal Cognitive Assessment (MoCA). CONCLUSION: Patients with ATD exhibit decreases in the parameters associated with fundus. In addition, these indicators significantly correlate with the MMSE score and the MoCA score. OCTA may be an adjunct tool with strong potential to track changes in the diagnosis and monitoring the progression of the disease.

Concomitant Retinal Alterations in Neuronal Activity and TNFα Pathway Are Detectable during the Pre-Symptomatic Stage in a Mouse Model of Alzheimer’s Disease

“…In line with this, a study published last year that focused on the evaluation of retinal function by ERG in cognitively healthy patients (asymptomatic in spite of Aβ-positive PET scans) showed important retinal ganglion cell dysfunctions, compared to the age-matched cognitively normal control with Aβ-negative PET scans [44]. Such functional pre-symptomatic assessment in subjects with Aβ-positive PET scans may further include structural examinations of the retinal vessel length, perfusion densities and choroid thickness in the macula area, which were all reported to decrease, at least during the advanced stages of AD [45]. In addition, the results obtained here argue for the consideration of the sampling of ocular fluids for future TNFα assessments as putative early AD biomarkers.…”

Optical coherence tomography and angiography in Alzheimer's disease and other cognitive disorders

“…In addition, the FAZ of AD patients appeared to be significantly compromised. 11,57,61,63 Beta-amyloid protein as mentioned earlier can accumulate in the retina of AD patients. The βA plaques would exert compressive forces on the retinal layers but also on the blood vessels, resulting in reduced blood flow, hypoxia and lack of glucose and other nutrients that are all essential for the metabolically very active retinal cells.…”

Macular Microvasculature Is Associated With Total Cerebral Small Vessel Disease Burden in Recent Single Subcortical Infarction

“…Simple computations for image analysis and explanations used in MoCA are done in the retina where previous studies have shown neurodegeneration and microvascular impairment. Although visual-related impediments in RSSI may be in part related to injury of the subcortical areas of the brain, the correlation between the retinal microvasculature/choroidal thickness in cognitive impairment in neurodegenerative diseases such as Alzheimer's disease has been reported while little is known in RSSI (Czako et al, 2020 ; Li et al, 2021 ). Our current report showing the correlation between retinal microvasculature and choroidal thickness and MoCA scores suggests that the inner retinal microvasculature and choroidal thickness may be useful to examine RSSI patients for potential cognitive impairment.…”

“…Yet very few reported on the retinal vascular changes and their correlation with the clinical implications. Following the advent of the optical coherence tomography angiography (OCTA), in vivo studies have shown significant changes in the retina and choroid of patients with neurodegenerative diseases such as Parkinson's disease (Robbins et al, 2021 ) and Alzheimer's disease (Li et al, 2021 ); these reports have suggested that the retina and choroid could be a potential early and non-invasive microvascular indicator for these diseases. However, very little is known about the clinical use of structural and microvasculature of the retinal capillary network and choroid in RSSI; this may be due to the persistent encounter of explicitly detecting the cause of RSSI clinically.…”