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Lily Yu-Li Chang, Monica L Acosta, Joanna Black; Window to the central nervous system–Retinal examination for early diagnosis of Alzheimer’s disease. Invest. Ophthalmol. Vis. Sci. 2016;57(12):3371.
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© ARVO (1962-2015); The Authors (2016-present)
Alzheimer’s disease (AD) is a public health priority due to population aging. The diagnosis is often delayed, and is the major obstacle to therapeutic success. The eye has attracted much interest for effective detection of AD due to distinctive visual symptoms in early stages of AD. Recent studies have shown proteins implicated in AD may be identified in vitro, and more recently, in vivo, through retinal imaging. We therefore hypothesized that visual disturbances in AD may be attributed to changes in the retina, and that there are differences in retinal structure and function between healthy controls and AD patients, detectable byan eye examination.
Retinal structure and function were assessed in 3 group of people in a pilot study. 32 participants were enrolled as young controls(age 18-59,N=20), elderly controls(age≥60,N=8), and dementia patients(age≥60,N=4) including AD(N=2), cerebral amyloid angiopathy(N=1) and vascular dementia(N=1). Retinal structure was assessed by fundoscopy, and optical coherence tomography (OCT). Retinal ganglion cell and macula function were assessed by pattern electroretinogram (PERG) and multifocal ERG (MfERG). Mann-Whitney U test and 95% confidence interval was used for statistical analysis.
OCT showed no significant difference between young and elderly controls. There was a significant difference in PERG latency, MfERG amplitude and latency (p<0.05) between the young and elderly controls. This suggested an aging effect in retinal function but not in retinal structure. All dementia patients had retinal thinning in the temporal quadrant(s) of the optic nerve, and in the macula compared to elderly controls. This structural thinning was mirrored by delayed latency and amplitude in both PERG and MfERG. AD cases had the greatest retinal thinning and the most delayed MfERG latency compared to other dementia.
These findings provide evidence that there is a decline in retinal structure and function in AD. We speculate this extent of decline results from a chronic process, and could have started at pre-dementia stage. The decline of retinal integrity in AD also shows distinctive difference from other dementia. Retinal examination requires minimal cognitive input and is easy to perform in clinic. This investigation suggests that retinal examinations combined with other ocular tests has the potential to be employed as clinical markers for AD.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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