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.[Figure not available: see fulltext.]