Abstract
Purpose :
To quantitatively characterize macrophage-like cells (MLC) at the vitreoretinal interface using optical coherence tomography angiography (OCTA) in different severity stages of diabetic retinopathy (DR).
Methods :
72 eyes of 72 subjects (age 46.0 ± 13.6 years)—18 healthy controls, 22 diabetics without DR (DM no DR), 17 with non-proliferative DR (NPDR), and 15 with proliferative DR (PDR)—were included. Repeated (average 6.5; range 3-10) OCTA scans were obtained for each eye. We segmented, registered and averaged the 3-µm OCT slab above the vitreoretinal interface to visualize MLC distribution, and the OCTA slab of the underlying superficial capillary plexus to compare MLC distribution to vascularity. MLCs were binarized using a semi-automated method and quantified. We compared MLC density in the area overlying blood vessels, within the perivascular 30-µm watershed region, and within ischemic areas (> 30 µm from nearest vessel).
Results :
MLC density was 6.4 ± 7.0 cells/mm2 in healthy controls, 7.8 ± 6.5 cells/mm2 in DM no DR, 5.8 ± 4.1 cells/mm2 in NPDR, and 21.9 ± 19.4 cells/mm2 in PDR. MLC density was higher in PDR compared to all other groups (2.8 to 3.8-fold; p < 0.01 for all). We next investigated the location of increased MLC density in PDR. MLC density was most increased in perivascular areas (4.9 to 10.2-fold, p < 0.002 vs. all groups), up-regulated on blood vessels (3.1 to 3.9-fold, p < 0.012 vs. all groups), and marginally elevated in ischemic areas (2.1 to 3.4-fold, p < 0.033 vs. all groups).
Conclusions :
MLC density is significantly increased in PDR and was more pronounced in the perivascular region and on blood vessels compared to ischemic areas, suggesting a potential role of MLCs in retinal inflammation or damage. As the noninvasive nature of OCT precludes definitive identification of MLCs in this study, further study is needed to confirm their identity and function.
This is a 2021 ARVO Annual Meeting abstract.