Vessel Density Changes on Optical Coherence Tomography Angiography after Vascular Endothelial Growth Factor Inhibitor Treatment for Diabetic Macular Edema

Abstract

Objectives: To evaluate the changes in macular vessel density after treatment with vascular endothelial growth factor (VEGF) inhibitors in center-involving diabetic macular edema (DME) and to compare these changes between anatomical responders and non-responders.

Materials and methods: This retrospective study included 22 eyes with center-involving DME. All eyes had 3 consecutive administrations of VEGF inhibitors. Optical coherence tomography (OCT) and OCT angiography (OCTA) of the macula with manual adjustment of segmentation lines were performed at baseline and after treatment. Vessel density in the central and parafoveal regions of the superficial and deep capillary plexus (SCP/DCP) were measured at baseline and after treatment. Vessel density and changes therein were compared between anatomical responders and non-responders as defined by changes in central subfield thickness (CST).

Results: Overall, there were no significant differences in vessel density in the central and parafoveal regions of the SCP and DCP after treatment compared to baseline. After categorization by anatomical response, 12 eyes were responders (CST decreased by 173.7±47.7 μm) and 10 eyes were non-responders (CST increased by 20.8±38.9 μm) (p<0.0001). There were no corresponding significant differences between responders and non-responders in SCP and DCP vessel density or changes therein after treatment.

Conclusion: There were no significant changes in macular vessel density after the early stages of VEGF inhibitor treatment for DME, and there was no relationship with the anatomical response. The effect of VEGF inhibitors in DME treatment may not be related to increasing vessel density.

Keywords: Optical coherence tomography angiography; deep capillary plexus; superficial capillary plexus; treatment response; vascular endothelial growth factor inhibitor; vessel density.

Figure 1

Schematic diagram of the 3 mm ETDRS grid centered over the fovea. The central 1-mm sector (shown in white) is the central region. The parafoveal region is the area (shown in gray) between the central 1-mm sector and the boundary of the 3-mm grid. The vessel density of the parafoveal region is the mean of the vessel density of the 4 sectors surrounding the central region. The average vessel density of the SCP and DCP were calculated as the mean of the vessel density of the area encompassed by the entire grid ETDRS: Early treatment of diabetic retinopathy study, SCP: Superficial capillary plexus , DCP: Deep capillary plexus

Figure 2

Serial multimodal images of a responder and non-responder. The vessel density (VD) of the superficial capillary plexus (SCP) and deep capillary plexus (DCP), optical coherence tomography (OCT) images of the macula, and fundus photographs at baseline and after the third visit are shown. Responder: Though the responder demonstrated anatomical improvement with a decrease in central subfield thickness, intraretinal fluid, subretinal fluid, and cystic spaces, there was no significant corresponding change in the vessel density in the SCP and DCP. Non-responder: The non-responder demonstrated anatomical worsening. Similarly, there was also no significant corresponding change in the vessel density in the SCP and DCP