Retinal oxygen metabolism in patients with mild cognitive impairment

Ólafsdóttir, Ólöf Birna; Saevarsdottir, Hrafnhildur Sif; Hardarson, Sveinn Hákon; Hannesdóttir, Kristín; Traustadottir, Valgerdur Dora; Karlsson, Robert Arnar; Einarsdóttir, Anna Bryndís; Jonsdottir, Katrin Dilja; Stefánsson, Einar; Snædal, Jón

doi:10.1016/j.dadm.2018.03.002

Cited by 32 publications

(25 citation statements)

References 36 publications

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“… Einarsdottir et al (2016) were the first to report oximetry abnormalities in retinas of AD patients compared with a healthy cohort. These findings have recently been confirmed and extended to patients with MCI ( Olafsdottir et al, 2018 ) ( Figure 6 ). Further studies are needed to confirm and expand the utility of retinal oximetry in AD clinical practice and trials.…”

Section: Functional Imaging Methodssupporting

confidence: 65%

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Potential Utility of Retinal Imaging for Alzheimer’s Disease: A Review

Liao

Zhu

Peng

2018

Front. Aging Neurosci.

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The ensuing upward shift in demographic distribution due to the increase in life expectancy has resulted in a rising prevalence of Alzheimer’s disease (AD). The heavy public burden of AD, along with the urgent to prevent and treat the disease before the irreversible damage to the brain, calls for a sensitive and specific screening technology to identify high-risk individuals before cognitive symptoms arise. Even though current modalities, such as positron emission tomography (PET) and cerebrospinal fluid (CSF) biomarker, showed their potential clinical uses in early detection of AD, the high cost, narrow isotope availability of PET probes and invasive characteristics of CSF biomarker limited their broad utility. Therefore, additional tools for detection of AD are needed. As a projection of the central nervous system (CNS), the retina has been described as a “window to the brain” and a novel marker for AD. Low cost, easy accessibility and non-invasive features make retina tests suitable for large-scale population screening and investigations of preclinical AD. Furthermore, a number of novel approaches in retina imaging, such as optical coherence tomography (OCT), have been developed and made it possible to visualize changes in the retina at a very fine resolution. In this review, we outline the background for AD to accelerate the adoption of retina imaging for the diagnosis and management of AD in clinical practice. Then, we focus on recent findings on the application of retina imaging to investigate AD and provide suggestions for future research directions.

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Section: Functional Imaging Methodssupporting

confidence: 65%

“… Example of fundus oximetry images from (above) a age-adjusted healthy individual and (below) an mild cognitive impairment patient ( Olafsdottir et al, 2018 ). …”

Section: Functional Imaging Methodsmentioning

confidence: 99%

Potential Utility of Retinal Imaging for Alzheimer’s Disease: A Review

Liao

Zhu

Peng

2018

Front. Aging Neurosci.

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“…Analysis of patients with AD suggests that the retina undergoes significant remodeling during the course of the disease, with both increases53 and decreases54,55 in retinal thickness observed using OCT. AD patients also have profound changes in oxygen metabolism,56 and an overall decrease in the retinal vasculature density,57 which may contribute to or result from abnormal functional and structural retinal outcomes in this disease. It is possible that the RGC functional loss on the PERG response analysis was related to the observed reductions in density of ganglion cells (see Fig.…”

Section: Discussionmentioning

confidence: 99%

Blast-Mediated Traumatic Brain Injury Exacerbates Retinal Damage and Amyloidosis in the APPswePSENd19e Mouse Model of Alzheimer's Disease

Harper

Hedberg-Buenz

Herlein

et al. 2019

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. Traumatic brain injury (TBI) is a risk factor for developing chronic neurodegenerative conditions including Alzheimer's disease (AD). The purpose of this study was to examine chronic effects of blast TBI on retinal ganglion cells (RGC), optic nerve, and brain amyloid load in a mouse model of AD amyloidosis. METHODS. Transgenic (TG) double-mutant APPswePSENd19e (APP/PS1) mice and nontransgenic (Non-TG) littermates were exposed to a single blast TBI (20 psi) at age 2 to 3 months. RGC cell structure and function was evaluated 2 months later (average age at endpoint ¼ 4.5 months) using pattern electroretinogram (PERG), optical coherence tomography (OCT), and the chromatic pupil light reflex (cPLR), followed by histologic analysis of retina, optic nerve, and brain amyloid pathology. RESULTS. APP/PS1 mice exposed to blast TBI (TG-Blast) had significantly lower PERG and cPLR responses 2 months after injury compared to preblast values and compared to sham groups of APP/PS1 (TG-Sham) and nontransgenic (Non-TG-Sham) mice as well as nontransgenic blastexposed mice (Non-TG-Blast). The TG-Blast group also had significantly thinner RGC complex and more optic nerve damage compared to all groups. No amyloid-b (Ab) deposits were detected in retinas of APP/PS1 mice; however, increased amyloid precursor protein (APP)/Abimmunoreactivity was seen in TG-Blast compared to TG-Sham mice, particularly near blood vessels. TG-Blast and TG-Sham groups exhibited high variability in pathology severity, with a strong, but not statistically significant, trend for greater cerebral cortical Ab plaque load in the TG-Blast compared to TG-Sham group. CONCLUSIONS. When combined with a genetic susceptibility for developing amyloidosis of AD, blast TBI exposure leads to earlier RGC and optic nerve damage associated with modest but detectable increase in cerebral cortical Ab pathology. These findings suggest that genetic risk factors for AD may increase the sensitivity of the retina to blast-mediated damage.

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“…Retinal oxygen saturation has been suggested as a mirror to brain oxygenation. In studies on mild cognitive impairment and multiple sclerosis patients [ 91 , 92 ], retinal arteriovenous oxygen saturation difference was significantly lower than that of healthy persons, which reflects reduced oxygen extraction in the retina, indicating reduced metabolism.…”

Section: Pulse Oximetry—theory and Techniquesmentioning

confidence: 99%

The Various Oximetric Techniques Used for the Evaluation of Blood Oxygenation

Nitzan

Arieli

2020

Sensors

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Adequate oxygen delivery to a tissue depends on sufficient oxygen content in arterial blood and blood flow to the tissue. Oximetry is a technique for the assessment of blood oxygenation by measurements of light transmission through the blood, which is based on the different absorption spectra of oxygenated and deoxygenated hemoglobin. Oxygen saturation in arterial blood provides information on the adequacy of respiration and is routinely measured in clinical settings, utilizing pulse oximetry. Oxygen saturation, in venous blood (SvO2) and in the entire blood in a tissue (StO2), is related to the blood supply to the tissue, and several oximetric techniques have been developed for their assessment. SvO2 can be measured non-invasively in the fingers, making use of modified pulse oximetry, and in the retina, using the modified Beer–Lambert Law. StO2 is measured in peripheral muscle and cerebral tissue by means of various modes of near infrared spectroscopy (NIRS), utilizing the relative transparency of infrared light in muscle and cerebral tissue. The primary problem of oximetry is the discrimination between absorption by hemoglobin and scattering by tissue elements in the attenuation measurement, and the various techniques developed for isolating the absorption effect are presented in the current review, with their limitations.

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Retinal oxygen metabolism in patients with mild cognitive impairment

Cited by 32 publications

References 36 publications

Potential Utility of Retinal Imaging for Alzheimer’s Disease: A Review

Potential Utility of Retinal Imaging for Alzheimer’s Disease: A Review

Blast-Mediated Traumatic Brain Injury Exacerbates Retinal Damage and Amyloidosis in the APPswePSENd19e Mouse Model of Alzheimer's Disease

The Various Oximetric Techniques Used for the Evaluation of Blood Oxygenation

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