Reexamine the link between retinal layer thickness and cognitive function after correction of axial length: the Beijing Eye Study 2011.

Purpose: To investigate the relationship between retinal layer thickness and cognitive function in elderly Chinese, accounting for the influence of axial length.

Methods: The participants of the Beijing Eye Study 2011 which is a population-based cross-sectional study without any retinal or optic nerve disease underwent a series of ocular examinations including spectral-domain optical coherence tomography (OCT) of the retina. Using a multiple-surface OCT segmentation algorithm, the retina was automatically segmented into 9 layers. Cognitive function was evaluated applying the Mini Mental Statement Examination (MMSE). Cognitive impairment was defined as an MMSE score < 26.

Results: The study included 2067 participants (56.7% women) (2067 eyes) with a mean age of 61.4 ± 8.4 years. After adjusting for age, gender and axial length, a lower cognitive function was related with a thinning of the ganglion cell layer (GCL) (P = 0.029, B = 0.04) and photoreceptor outer segment layer (POS) (P = 0.042, B = 0.04), while the retinal nerve fiber layer (RNFL) thickness (P = 0.144) was not significantly associated with the cognitive function score. For every unit decrease in MMSE score, the GCL and POS thickness separately decreased by 0.06 µm (95%CI: 0.01 µm, 0.12 µm), and 0.05 µm (95%CI: 0.002 µm, 0.10 µm). As compared with cognitively normal participants, those with cognitive impairment had a significantly thinner GCL (P = 0.019, OR = 1.04), and POS (P = 0.022, OR = 1.04) in multivariate logistic regression.

Conclusion: After adding axial length as dependence in multivariate analysis, cognitive impairment was not significantly associated with the thickness of RNFL, while the association between a lower cognitive function score and thinner GCL and POS was statistically associated in current study.