Associating retinal layer thicknesses of the macula with cognitive speed and executive function

Abstract

Purpose : To associate ten macular retinal layer thicknesses with cognitive speed and executive function.

Methods : From the age and sex stratified, population-based LIFE-Adult-Study, spectral domain optical coherence tomography (OCT) volume scans of the macula (97 horizontal B-scans, each consisting of 512 A-scans) were selected from participants with reliable measurements (quality ≥20 dB) who underwent cognitive assessment by both parts of the trail-making test (TMT; illustrated in Fig. 1A), with TMT Part A testing cognitive speed and Part B assessing executive function. On each B-scan, ten retinal layers were segmented (Fig. 1B). Separately for each of these layers, at each of the 49,664 A-scans, partial Pearson correlations between layer thickness and each TMT part adjusted for age were calculated. P-values were adjusted for multiple comparisons by the false-discovery method.

Results : 17,759 eyes of 8,958 subjects were included (4,670 female/4,288 male; age range: 20-79 years). Figure 2 shows the pointwise partial correlation maps for each layer and test. Inner retinal layers were stronger associated with both TMT subtests than outer layers. The largest percentage of significant retinal locations was found for the retinal nerve fiber layer (RNFL; TMT-A/B: 72%/68%), followed by the ganglion cell layer (GCL; TMT-A/B: 48%/26%). Generally, TMT-A (cognitive speed) was stronger associated with layer thicknesses than TMT-B (executive function), but amount and spatial arrangement of the associations are similar for both subtests, with the notable exception of the outer photoreceptor segment thickness, which is significantly correlated over 29% of the macula with TMT-A but entirely uncorrelated with TMT-B. Thinner inner layers over large macular areas are related to worse cognitive performance. Layer thinning spares areas nasal to the fovea for RNFL and is ring-shaped around the fovea for most other inner layers.

Conclusions : Previous dementia studies related cognitive decline to thinning of a single retinal layer (RNFL) and typically analyzed areas close to the optic disc. Here, we analyze ten retinal layers of the macula and demonstrate associations between worse cognitive performance and reduced retinal layer thickness over large areas. This was most pronounced for RNFL and GCL, two layers that are also closely related to optic nerve damages, but selected effects also occurred in outer layers.

This is a 2021 ARVO Annual Meeting abstract.

 

Fig.1

 

Fig.2