Computational analysis of spatial correspondence between intraretinal, subretinal and sub-RPE fluid in neovascular AMD

Abstract

Purpose : Evidence suggests that subretinal fluid (SRF) may be associated with favorable visual prognosis in the therapy of neovascular age-related macular degeneration (nAMD), while intraretinal cystoid fluid (IRC) correlates with poorer vision. The aim of this retrospective, cross-sectional study was to gain additional insight into structure-function correlation by analyzing the spatial correspondence between the main pathomorphologic components in nAMD, i.e., IRC, SRF and pigment-epithelial detachment (PED). We hypothesized that IRC occur mainly co-localized with PED, while SRF appears spatially anti-correlated with the other two components.

Methods : SD-OCT volume scans (128 B-scans, 6x6mm) of 616 patients with treatment-naïve nAMD available at the Vienna Reading Center were included. IRC, SRF and PED were detected on a per-voxel basis using fully automated segmentation algorithms. For validation, IRC and SRF were segmented manually in a separate set of 38 patients. To quantify the spatial correspondence of IRC/SRF/PED lesions, we calculated the percentages of IRC-, SRF-, or PED-affected A-scans also affected by one or both of the respective other pathomorphologic components and reported the median across the population.

Results : 78,848 OCT B-scans were analyzed automatically and 4,864 manually. Of the 6x6mm area covered by the SD-OCT scan, a mean of 9% was affected by IRC, 15% by SRF and 7% by PED. In the 616 automatically processed eyes, averaged spatial correspondence between the features was as follows: Of IRC-affected A-scans 16% presented with SRF, 36% with PED. Of SRF-affected A-scans 10% presented with IRC, 6% with PED. Of PED-affected A-scans 44% presented with IRC, 11% with SRF. In the 1-mm central foveal region, similar patterns were observed (Table 1). In the 38 manually segmented validation cases, consistent results were obtained (Table 1). Representative example cases are provided in Figure 1.

Conclusions : In treatment-naïve nAMD, IRC most frequently appear above PED. In contrast, SRF appears spatially anti-correlated to PED and IRC. Thus, the positive effects of SRF on visual function may be attributed to a lower likelihood of concomitant IRC in the same area.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

Table 1

 

Figure 1: Automatically (a,b) and manually (c) segmented example cases