Morphological and functional retinal impairment in Alzheimer's disease patients

Objective: Our study aims to assess the optic nerve fiber layer thickness in vivo, the function of the innermost retinal layer and whether a correlation exists between morphological and functional parameters in patients affected by Alzheimer's Disease (AD). Methods: Seventeen AD patients (mean age 70.37 +/- 6.1 years, best corrected visual acuity >8/10 with refractive error between +/-3 sf, intra-ocular pressure (IOP) < 18 mmHg) were enrolled. They were compared to 14 age-matched controls. Nerve fiber layer (NFL) thickness was measured by optical coherence tomography (OCT). Three different measurements in each quadrant (superior, inferior, nasal, and temporal) were taken and averaged. The data in all quadrants (12 values averaged) were identified as NFL Overall. Retinal function was assessed by pattern electroretinogram (PERG) recordings using high-contrast (80%) checkerboard stimuli subtending 15 min of the visual are and reversed at the rate of two reversals/s. Results: In AD eyes, there was a significant (P 0.01) between NFL values and other PERG parameters (N35 implicit time, N35-P50 amplitude) were found. Conclusions: Our results suggest that in AD patients, there is a reduction of NFL thickness evaluated in vivo by OCT and this morphological abnormality is related to a retinal dysfunction as revealed by abnormal PERG responses