Retinal Nerve Fiber Layer Thickness in an elderly population: correlation with the cognitive performances in the ALIENOR Study

Abstract

Purpose: : Alzheimer disease and other cognitive impairments become a challenging public health problem. Diagnosing these diseases earlier could lead to better treatment and outcome. It has been suggested that Retinal Nerve Fiber Layer (RNFL) thickness, which is an easy and safe eye examination, is thinner in Alzheimer's patients than in normal population. Nevertheless, previous studies had been conducted on small samples of patients. The aim of our study was i) to establish normative data of RNFL thickness in the elderly population; ii) to examine relationship between RNFL thickness and cognitive performances.

Methods: : The ALIENOR (Antioxydants, Lipides Essentiels, Nutrition and maladies OculaiRes) Study is a population-based epidemiological study on nutrition and age-related eye diseases. In 2009-2010, 591 subjects, aged 77 years or more had a RNFL thickness measurement obtained with a Spectralis SD-OCT (Heidelberg, Germany). The MMSE (Mini Mental State Examination, global performances), Benton (visual memory), Isaacs (verbal fluency) and Free and Cued Selective Reminding (episodic memory) tests were used for neuropsychological assessment.

Results: : 59 subjects were excluded because of a diagnosis of glaucoma. The mean RNFL thickness among the non-glaucoma population was 91µm (SD 12.7). Men had significantly thinner RNFL than women (89.2; SD 12.6 versus 92.1, SD 12.6, p=0.005). RNFL decreased significantly with age, from 93.0 (SD 12.0) in subjects younger than 80 to 90.1 (SD 12.9) in subjects older than 85 years (p=0.003). After multivariate adjustment, the lowest quartile of RNFL thickness (<78µm) was associated with lower performance at the Benton test (p=0.04). There were no significant associations with the other tests.

Conclusions: : This study provided normative data on RNFL thickness in an elderly population. Furthermore, it demonstrated a positive correlation between lower RNFL thickness and lower Benton score.

Keywords: optic nerve • aging