Vitreomacular Interface: From Anterior to Tangential Traction

Anomalous posterior vitreous detachment (PVD) plays a major role in the formation of anterior-posterior and tangential epiretinal traction. Advances in the tomographic analysis of vitreous traction vectors have highlighted the selected cases that can benefit from " parasurgical " approaches, providing a different perspective for therapeutic strategies. The symptomatic anterior-posterior traction recently gained crescent interest for the application of enzymatic vitreolysis (ocriplasmin, IVO), mainly in small traction associated with full thickness macular hole. On the other hand, the outer layer of posterior vitreous cortex leads to tangential traction responsible for the formation of macular pucker. As reported by M. R. Romano et al., the presence of vitreoschisis associated with a strong vitre-opapillary adhesion of posterior cortex enhances the force of the tangential vector, inducing potential damage to the inner nuclear and outer plexiform layers. They also reported the epiretinal presence of glial fibrillary acidic protein (GFAP), indicating the ability of these cells to proliferate and migrate on the retinal surface. The transdifferentiated epiretinal cells are characterized by a downregulation of GFAP and cytok-eratins, while proteins involved in motility and proliferation, such as í µí»¼-smooth muscle actin, are upregulated. Therefore, the GFAP content in epiretinal tissues has been shown to correlate directly with tractional forces and inversely with the clinical contractility. D. Compera et al. reported interesting histology findings on the presence of GFAP positive cells in lamellar-hole (LMH) associated epiretinal proliferation. The authors hypothesize that the vitreous derived cells, rather than cells of glial origin, may play a relevant role in the pathogenesis of tangential traction. In LMH, differently from macular pucker, the traction is not increased by the contraction of í µí»¼-smooth muscle actin (í µí»¼-SMA), as í µí»¼-SMA-positive myofibroblasts were an infrequent finding in epiretinal proliferation associated with LMH, in their report. D. Agarwal et al. highlighted the presence of a tangential traction due to the thickened premacular vitreous cortex in diabetic patients. The authors also described a significant relationship between PVD and lack of macular edema, suggesting the importance of the vitreous cortex, embedded with fibroblasts and astrocytes, in the development and progression of diabetic retinopathy. The different adhesion at the interfaces seems to be sustained by factors such as VEGF, CCL2, IL-6, IL-8, and IL-18, also encouraging neovascularization and therefore worsening visual outcome. Surgical treatment is still the main approach in the management of the tangential tractional membranes. F. Semeraro et al. showed that the pathological …