Macular OCT measurements holds potential as a biomarker of cognitive function

In a cross-sectional, population-based survey, the authors determined the association between retinal thickness and cognitive function. 

Study design

A total of 1,293 Japanese people aged 65 to 86 years underwent a comprehensive exam, including spectral-domain OCT and mental health examinations; 975 were included in the analysis. The cohort was divided into 3 groups: healthy, mild cognitive impairment and dementia.

Outcomes

Retinal layers and ganglion cell complex (GCC) thickness were significantly different in all 3 groups, but not peripapillary retinal nerve fiber layer (ppRNFL) thickness. Macular and GCC thicknesses were associated with the presence of dementia, but ppRNFL thickness was not. Ganglion cell-inner plexiform layer, GCC and full macular thicknesses were all associated with the presence of dementia in the inferior sectors.

Limitations

One limitation of the study includes its cross-sectional, observational design, which does not provide temporal information. The authors did not determine the type of dementia, which may have limited the ability to detect an association between the cognitive function and the examined variables, such as retinal thickness. The number of participants with dementia was small. Future studies are needed to validate these findings in longitudinal large cohort studies with advanced OCT.

Clinical significance

These results indicate that macular thickness, but not ppRNFL, was associated with the presence of dementia. The authors suggest that OCT measurements of the macula could be superior to those of the ppRNFL in assessing neurodegenerative changes, and a potentially useful diagnostic marker of cognitive function.