The relationship between the degree of cognitive impairment and retinal nerve fiber layer thickness

Abstract

The goal of the present study is to investigate the relationship between the degree of cognitive impairment and retinal nerve fiber layer (RNFL) thickness which is measured by the optical coherence tomography (OCT). Thirty-five patients with Alzheimer's disease (AD), 35 patients with mild cognitive impairment (MCI), and 35 healthy volunteers, between the ages of 60-87, who were examined in the neurology outpatient clinic among 2012-2013 were prospectively involved in our study. Mini mental state examination (MMSE) test, montreal cognitive assessment (MOCA), and also neuropsychological test batteries were used for the neurocognitive evaluation. RNFL thickness was measured by the OCT technique and the differences among groups were studied. The relationship between RNFL thickness and MMSE scores with demographic characteristics was investigated. RNFL thickness was significantly lower in AD and MCI groups compared with the control group (p < 0.01). No significant differences of RNFL were found between the MCI and the AD groups (p > 0.05). Significant correlation was found between MMSE scores and the RNFL values (p < 0.05). Significant thinning in RNFL along with age was detected (p < 0.05). In our study, it is thought that retinal nerve fiber degeneration and central nervous system degeneration may be concurrent according to the thinning of RNFL measured by OCT in AD and MCI groups. RNFL measurement may also be useful for early diagnosis and evaluation of the disease progression. Further studies are needed to optimize the utility of this method as an ocular biomarker in AD.

How strong is the relationship between glaucoma, the retinal nerve fibre layer, and neurodegenerative diseases such as Alzheimer’s disease and multiple sclerosis?

“…The range of MMSE scores in the Berisha et al group was 17-30, whereas those reported by Iseri et al 82 were 8-28 and 11-19 in the study by Parisi et al 11 This further supports the notion that early retinal changes in AD may be confined to inferior and superior retina. Other studies have shown a significant correlation between RNFL thickness and MMSE scores in patients with MCI and AD 86 and RNFL thickness has been significantly associated with other cognitive domains including reaction times. 87 However, the findings are not universal: both an inverse association 88 and no association 89 between RNFL and cognitive test scores have been reported.…”

Cognitive performance of primary open-angle glaucoma and normal-tension glaucoma patients

“…The literature did not reveal any studies with similar glaucoma and dementia parameters for glaucoma patients. In some studies performed on dementia-group diseases causing cognitive impairment, a significant correlation was found between the MMSE score and RNFL thickness (30,31) . In addition, in a study by Bayhan et al, a significant correlation was (32) found between the MMSE score and the mean GC-IPL thickness.…”

Alzheimer’s disease: A review of its visual system neuropathology. Optical coherence tomography—a potential role as a study tool in vivo

“…Whether or not a correlation exists between retinal changes and severity of dementia also remains a controversial issue. While most OCT studies did not show correlation between Minimal Mental State Examination (MMSE) and peripapillary RNFL thinning (Table 2), one TD-OCT study reported correlation between MMSE scores and macular volume [44], and more recent studies using SD-OCT have indeed reported a significant correlation between MMSE scores and RNFL thickness [50,66,72,76,77]. Studies comparing changes in RNFLT in MCI and AD (Table 2) have also yielded conflicting results, although the majority reported no statistically significant differences between MCI and AD patient groups [46,47,54,77].…”