Thinner changes of the retinal nerve fiber layer in patients with mild cognitive impairment and Alzheimer's disease

Background: Alzheimer's disease (AD) is the most common form of dementia and patients often have visual disorders. Mild cognitive impairment (MCI) is characterized by a memory deficit when compared with those of a similar age and education level which could indicate an earlier onset of AD. The aim of this study is to measure the changes of the retinal nerve fiber layer (RNFL) thickness of AD and MCI patients in comparison with the normal age controls. Methods: The RNFL thickness was assessed using optical coherence tomography (OCT) in patients with MCI, AD (mild, moderate and severe) and the age matched controls. Results: The thickness of RNFL in the superior quadrant and total mean values are gradually and significantly decreased from MCI to severe AD when compared to that in the controls. There is also a significant reduction of the retinal nerve fiber layer in the inferior quadrant in severe AD patients. Conclusions: Our data indicate that the retinal nerve fiber layer degeneration is paralleled with dementia progression. Owing to its non-invasive and cost effective nature, monitoring RNFL thickness may have a value in assessing disease progression and the efficacy of any treatments.