Location-Specific Thickness Patterns in Intermediate Age-Related Macular Degeneration Reveals Anatomical Differences in Multiple Retinal Layers

Abstract

Purpose To examine individual retinal layers’ location-specific patterns of thicknesses in intermediate age-related macular degeneration (iAMD) using optical coherence tomography (OCT). Methods OCT macular cube scans were retrospectively acquired from 84 iAMD eyes of 84 participants and 84 normal eyes of 84 participants propensity-score matched on age, sex, and spherical equivalent refraction. Thicknesses of the retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer + Henle's fiber layer (ONL +HFL ), inner- and outer-segment layers (IS/OS), and retinal pigment epithelium to Bruch's membrane (RPE-BM) were calculated across an 8 × 8 grid (total 24° × 24° area). Location-specific analysis was performed using cluster (normal) and grid (iAMD) -to-cluster (normal) comparisons. Results In iAMD versus normal eyes, the central RPE-BM was thickened (mean difference ± SEM up to 27.45% ± 7.48%, P < 0.001; up to 7.6 SD-from-normal), whereas there was thinned outer (OPL, ONL +HFL , and non-central RPE-BM, up to −6.76% ± 2.47%, P < 0.001; up to −1.6 SD-from-normal) and inner retina (GCL and IPL, up to −4.83% ± 1.56%, P < 0.01; up to −1.7 SD-from-normal) with eccentricity-based effects. Interlayer correlations were greater against the ONL +HFL (mean |r| ± SEM 0.19 ± 0.03, P = 0.14 to < 0.0001) than the RPE-BM (0.09 ± 0, P = 0.72 to < 0.0001). Conclusions Location-specific analysis suggests altered retinal anatomy between iAMD and normal eyes. These data could direct clinical diagnosis and monitoring of AMD toward targeted locations.

High-Density Optical Coherence Tomography Analysis Provides Insights Into Early/Intermediate Age-Related Macular Degeneration Retinal Layer Changes

“… Macular volume scans within the SPECTRALIS HRA+OCT Viewing Module were automatically segmented and manually corrected to define the retinal layers in each B-scan ( A ). 17 Note that automatic segmentation boundaries were manually corrected to continue through large vasculature ( magenta insert , asterisk ), combine Henle's fiber layer with the ONL ( cyan insert , arrowhead ), and resolve mis-segmentation around drusen ( cyan insert , dagger ). Grids that were completely covered, such as by retinal blood vessel shadowing ( yellow ), were manually excluded.…”

“… 16 – 21 This moderate-density analysis revealed that normal macular gridwise thicknesses could be assigned to spatial groups of statistically similar within-group data and statistically separable between-group data (i.e., clusters, representative of normal macular anatomical topography and less variable than ETDRS sectors). 19 Comparing intermediate AMD to normal eyes using moderate-density analysis revealed extensive topographical differences and potential interlayer relationships across most retinal layers 16 , 17 that had not been observed in previous ETDRS-based analyses, underlining the benefit of greater spatial (lateral) resolution for OCT thickness analysis.…”

“…There remained some unresolved questions associated with moderate-density analysis. 17 First, topographical patterns of thickness differences were equivocal in the retinal nerve fiber (RNFL) and inner nuclear layer (INL) and at the fovea of inner retinal layers. Correlations were also weak across most interlayer comparisons.…”

Semi-automated quantitative analysis of the middle limiting membrane in tubercular serpiginous-like choroiditis using swept-source optical coherence tomography

“…The OPL has also been shown to decrease in thickness with age and disease 18 . However, the reduction in OPL thickness is an important feature of early age-related macular degeneration (AMD) 18 – 22 . Thinning of the OPL may precede development of drusen 23 .…”

“…Thinning of the OPL may precede development of drusen 23 . The changes in OPL may occur due to early and progressive neurodegeneration in addition to neuronal migration and peripheral (extramacular proliferation) in AMD 18 , 19 . Similar mechanisms of OPL remodeling may occur in TB SLC, resulting in thinning of the OPL layer and formation of the MLM.…”