![]() Peripapillary RNFL thinning is the most common finding in many neurological conditions such as multiple sclerosis, stroke, neuromyelitis optica, Lewy Body Dementia, Parkinson’s disease and AD 31, 32, 33. OCT is widely used in clinical ophthalmology and is a promising tool for neurological research 25 due to its good reliability in a variety of Central Nervous System (CNS) pathologies 26, 27, 28 and high correlation with several visual electrophysiological techniques 29, 30. OCT is routinely used in ophthalmology to evaluate retinal integrity through high-resolution cross-sectional scans of retinal layers such as the RNFL and CGL at different locations such as the macula or papilla 23, 24. Optical coherence tomography (OCT) is a relatively inexpensive, innocuous, quick transpupillary technique that permits in vivo objective retinal measurements and quantification. Numerous postmortem histopathological studies reported RNFL and ganglion cell layer (GCL) reduction in AD patients 18, 19 although others demonstrated disparate results 20, 21, 22. Visual symptoms in AD are supposedly caused by damage to associative visual cortical areas 15, 16, however, there is mounting evidence that neuroretinal involvement could also be a contributing factor 17 and this has spurred interest in the search for retinal AD biomarkers 18, 19. Unmyelinated axons of retinal ganglion cells form the retinal nerve fiber layer (RNFL) which prolongs as the optic nerve and connects to the lateral geniculate nucleus (LGN) in the thalamus, which serves as the first relay center of the visual pathway.Ĭolor and contrast sensitivity impairment, worse depth and motion perception, visual field deficits and impaired visual acuity are often seen in AD patients 13, 14. The retina is considered an anatomical protrusion of the central nervous system with same embryological origins. Even though some biomarkers have been validated and integrated into the new clinical diagnostic criteria 9, 10, most show suboptimal test accuracy and either are very expensive such as detection of Aβ and Tau deposits in the brain using positron emission tomography (PET) or fairly invasive such as measurement of tau protein and Aβ peptide levels in cerebrospinal fluid (CSF) analysis 11, 12 Given the fact that diagnosis of AD is still complicated especially in the MCI stage, the search of inexpensive and noninvasive biomarkers is a promising area of research 8. Although some MCI patients can remain stable for decades or even return to cognitive normality, it is well established that amnestic and multi-domain MCI condition increases the risk of progressing to AD 6, 7. This prodromal phase is known as mild cognitive impairment (MCI), a clinically heterogeneous syndrome whose definition has evolved in last years 3, 4, 5 and can be due to many different etiologies (AD, vascular damage, depression,…). Before the onset of dementia, cognitive disorders progress slowly with minor cognitive impairment and without significant interference in daily activities. Clinical diagnostic criteria for AD do not discriminate with accuracy between different dementing etiologies 2. The analysis of other OCT measurements in other retinal areas and layers as biomarkers for AD should be tested further.Īlzheimer’s disease (AD) is a complex neurodegenerative disease and the most common cause of dementia 1. These results do not support the usefulness of peripapillary RNFL analysis as a marker of cognitive impairment or in discriminating between cognitive groups. The multivariate adjusted analysis revealed no significant differences in mean overall (p = 0.352), temporal (p = 0,119), nasal (p = 0,151), superior (p = 0,435) or inferior (p = 0,825) quadrants between AD, MCI and control groups. Adjustment by age, education, sex and OCT image quality was performed. 930 individuals (414 cognitively healthy individuals, 192 probable amnestic MCI and 324 probable AD) attending a memory clinic were consecutively included and underwent spectral domain OCT (Maestro, Topcon) examinations to assess differences in peripapillary RNFL thickness, using a design of high ecological validity. However, other studies have not shown such results. The use of optical coherence tomography (OCT) has been suggested as a potential biomarker for Alzheimer’s Disease based on previously reported thinning of the retinal nerve fiber layer (RNFL) in Alzheimer’s disease’s (AD) and Mild Cognitive Impairment (MCI).
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |