Quantitative assessment of hyperreflective dots in the outer nuclear layer over neovascular lesion components

To evaluate the outer nuclear layer for hyperreflective dots (HRD), a proposed imaging correlate of retinal microglia, in eyes with neovascular age-related macular degeneration (nAMD).

High-resolution optical coherence tomography (OCT) of eyes with nAMD was evaluated with the aid of a custom ImageJ plugin that automatically identified HRD and plotted them on the corresponding near infrared (IR) fundus image. Areas of subretinal fluid (SRF), double layer sign (DLS), and the area of neovascularisation as imaged by OCT angiography (A) were mapped to the near-IR image. The number of HRD overlying these regions was tabulated.

There were 38 eyes of 38 patients. SRF was present in 23 eyes, there was a median 8.5 HRD /mm² over this area. DLS was present in all eyes and with a median of 6.5 HRD/mm² over this area. Neovascularisation was detectable using OCTA with a median of 6.8 HRD/mm². The density of HRD/mm² was not significantly different over areas of DLS with fluid compared to areas of DLS without SRF (P = 0.22). The median HRD/mm² for uninvolved areas of the retina was 0.7, a difference that was significantly less than over areas of SRF, DLS, and OCTA detected neovascularisation (P < 0.001 for all comparisons).

There is an aggregation of HRD in the outer retina over lesion components of nAMD. These HRD may be present in response to SRF, but their existence over regions of the neovascular lesion without SRF suggests that additional factors are involved in their recruitment.