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.