Retinal layer thicknesses in early age-related macular degeneration: results from the German AugUR-study

Abstract

Purpose : Spectral domain-optical coherence tomography (SD-OCT) enables qualitative and quantitative measurements of retinal structures and is supposed to capture particularly early disease stages. Here, we determined retinal layer thicknesses in elderly individuals from a population-based study and investigated their association with early age-related macular degeneration (AMD).

Methods : In our SD-OCT sub-study of the AugUR research platform, we applied multimodal retinal imaging in 508 individuals aged 70-94 years. The protocol included color fundus images, which were graded for AMD (no/mild, moderate, severe early/late AMD; Three Continent AMD Consortium Severity Scale). Moreover, 20x20° macular cubes with 49 Raster lines and ≥30 automated real-time repetitions were acquired via the Spectralis SD-OCT. Retinal layers were automatically segmented using the Heidelberg Eye Explorer software, followed by manual corrections. Average retinal layer thicknesses were noted in central, inner, and outer macular circles (1, 3, 6 mm diameter; Early Treatment Diabetic Retinopathy Study grid; nasal, temporal, superior and inferior subfields combined). For each circle and each of the 10 retinal layers as predefined by the software, we tested association of thicknesses with early AMD stages using the Kruskal-Wallis test followed by Bonferroni-corrected pairwise comparisons (P<0.05/10*3*3=5.6x10^-4).

Results : After excluding eyes with late AMD on color fundus images or with low-quality/not centred SD-OCT scans, we selected one eye per participant (worse AMD status or random). Of these 449 eyes, 347 revealed no AMD and 102 any early AMD. Retinal pigment epithelium (RPE) in central or inner circles demonstrated significant thickening in moderate and severe early AMD compared to no AMD (Kruskal-Wallis P<0.0001; pairwise difference P=2.5*10^-5 to 1.85*10^-13, Table 1). Outer retinal layers including RPE were also thickened. We observed no difference of layer thicknesses when comparing mild early with no AMD and no evidence for age as a confounder.

Conclusions : Our analysis substantiates a quantitatively measureable difference in retinal layer thicknesses between no and early AMD, however not at the very beginning of disease. The here presented retinal layer thickness values may serve as references for the elderly population.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Table 1. Retinal layers which differ statistically significant between no and early AMD stages.