NEW INSIGHT INTO THE MACULAR DEEP VASCULAR PLEXUS IMAGED BY OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

Purpose: To describe the macular deep capillary plexus (DCP) in normal eyes using optical coherence tomography angiography.
Methods: Retrospective study including 41 consecutive normal eyes imaged using optical coherence tomography angiography (RTVue XR Avanti; Optovue Inc). Default autosegmentation of the superficial capillary plexus (SCP) and DCP, and manual adjustments of "deep settings" were used to analyze the organization of the normal macular microvascularization and to investigate in vivo the connection between these capillary networks.
Results: Mean age was 31 years (range, 22-55 years). The SCP and DCP had 2 different organizations, but the plexus autosegmentation was imperfect: In 68% of cases, the image of the SCP variably superimposed on the DCP, interfering with its analysis. The SCP was composed on average of 7 pairs of arterioles and venules obvious on each 3-mm × 3-mm optical coherence tomography angiography scanning area. The DCP was composed of a capillary vortex arrangement, whose centers were aligned along the course of the macular superficial venules.
Conclusion: The SCP and DCP had two different topographic organizations. The pattern of the capillary units converging into capillary vortexes highly suggests that they drain into the superficial venules. The different structural properties of the SCP and DCP could explain the differences in flow resistance and perfusion.