Macular capillary displacement in exudative and tractional macular oedema: a multimodal imaging study and pathophysiological hypothesis

Purpose This study aims to describe vessel density differences in tractional versus exudative macular oedema with the aid of novel custom imaging analysis techniques. Methods In this retrospective study, patients with exudative and tractional macular oedema were imaged with optical coherence tomography (OCT), en-face OCT, OCT-angiography and fluorescein angiography. A novel image processing algorithm was developed to extrapolate data from the vessel density maps. Results Forty- one eyes of 36 patients were included. A total of 30 control eyes comprised the control group. At the deep capillary plexus (DCP), exudative eyes presented with a vessel density of 62.12 +/- 5.7, significantly higher if compared to both tractional lamellar macular hole (57.6 +/- 4.6, p = 0.004) and controls (52.07 +/- 2.3, p < 0.001). At the superficial capillary plexus (SCP), there were no differences in vessel density between exudative eyes (51.9 +/- 4.4) and both the tractional lamellar hole (54.9 +/- 3.1, p = 0.083) and the control (51.72 +/- 2.2, p = 0.083) groups. In the exudative subgroup, there was a direct correlation between areas of low flow and those of high flow at both the DCP and SCP (p = 0.001 and p = 0.042, respectively). Conclusions Intraretinal expansion of fluid may cause the displacement of the surrounding retinal parenchyma and capillaries.

Automated summary

This study used novel imaging analysis techniques to describe vessel density differences between tractional and exudative macular oedema. Exudative eyes had higher vessel density in the deep capillary plexus compared to tractional eyes and controls, while no differences were found in the superficial capillary plexus. In exudative eyes, areas of low flow were directly correlated with areas of high flow in both the deep and superficial capillary plexus.