Retinal Histology and Anatomical Landmarks in Vitreoretinal Surgery

Awareness of important anatomical landmarks during vitreoretinal surgery contributes to favorable outcomes in the postoperative period. While external anatomical landmarks include pars plana, ora serrata, and vortex veins, long posterior ciliary nerves, vortex vein ampulla, and optic disc constitute the internal anatomical landmarks for vitreoretinal surgery. The forces that prevent the development of retinal detachment by keeping the retina in place are the retina pigment epithelium pump, the interphotoreceptor matrix, the presence of vitreous gel, and intraocular pressure. The main aim of the surgeon should be removing vitreous as much as possible and releasing vitreoretinal tractions which cause retinal detachment and vitreoretinal interface problems.

Enhanced Transport and Permeation of a Polymeric Nanocarrier across the Retina by Mixing with ATP upon Intravitreal Injection

The outer part of the retina pigment epithelium (RPE) in the retina is the main site of neovascularization associated with retinal diseases. However, various obstacles interrupt the delivery of medicines across the RPE, mainly due to the well-developed tight junctions in the RPE. Currently, there is no practical formulation to overcome this issue. In this study, we demonstrated that simple mixing with adenosine tetraphosphate (ATP) has the potential to greatly enhance the transport and permeation of a polymeric nanocarrier across the retina via intravitreal administration. Chitosan-functionalized, pluronic-based nanocarrier (NC), which can deliver various biomolecules efficiently, was used as a polymeric nanocarrier. Mixing with ATP facilitated the diffusion of the nanocarrier in the vitreous humor by reducing the electrostatic interaction between NC and negatively charged glycosaminoglycans (GAGs) in the vitreous humor. Mixing with ATP also allowed the penetration of NC across the whole retina, and it resulted in a great increase (approximately nine times) in the transport of NC across the retina, as well as spreading it throughout the whole retina upon intravitreal administration in a mouse model. This enhanced permeation across the retina was specific to ATP but not to GTP, suggesting the possibility of P2Y receptor-mediated tight junction disruption by ATP.

Electron Microscopic Retina Changes in Rabbit Eyes with Perfluorocarbon Liquids Intravitreal Tamponade

Purpose. Analysis of electron microscopic changes in rabbit eyes with intravitreal tamponade of perfluorocarbon liquids (PFCL) (perfluoro-1,3-dimethylcyclohexane and perfluorodecalin).Material and Methods. The study was performed on Chinchilla breed rabbits. 25G vitrectomy with PFCL intravitreal tamponade was performed on 12 eyes of 6 rabbits (perfluorodecalin (Bausch+Lomb «Dk-line», USA) and perfluoro-1,3-dimethylcyclohexane (ZAO “Optimedservis”, Russia). Standard three-port vitrectomy technique was used. After removal of the vitreous body 2.5 ml of PFCL were injected in vitreous cavity. Research studies were performed in 5, 14 and 30 days after surgery by electron microscopy. Eyes were enucleated in 20 minutes after animal was killed by air embolization. Intact eyes were used as a control. All samples were prepared in same conditions. The damage of the retina architectonics and the presence of intracellular inclusions were evaluated.Results. Tamponade of the vitreous cavity by both types of PFCL in 5, 14 and 30 day caused following similar electron microscopic changes at date: swelling ganglion layer and dystrophy of inner and outer nuclear layer. Electron microscopic changes in outer nuclear layer appeared at 30 days. The photoreceptor neurons were characterized by single ultrastructural changes. Retina pigment epithelium cells had a typical ultrastructure.Conclusion. Intravitreal perfluoro-1,3-dimethylcyclohexane tamponade caused similar electron microscopic changes as well as perfluorodecalin in the experiment and it was relatively harmless to rabbit retina for up to 14 days. Irreversible changes in the retinal ultrastructure were not observed.

High-Salt Enhances the Inflammatory Response by Retina Pigment Epithelium Cells following Lipopolysaccharide Stimulation

High-salt has been shown to play a role in the pathogenesis of autoimmune disease. In this study, we investigated the effect of high-salt on the production of inflammatory mediators by ARPE-19 cells and the possible mechanisms involved. ARPE-19 cells were cultured with LPS in DMEM to which extra NaCl had been added (20 mM and 40 mM). NaCl had no influence on the apoptosis and proliferation of ARPE-19. Addition of 40 mM NaCl significantly induced IL-6 and MCP-1 production but had no effect on IL-8 secretion. High mannitol, as an osmotic stress control, did not affect the secretion of inflammatory mediators by ARPE-19 cells indicating that the effect was not mediated by osmolarity. Coculture of ARPE-19 cells with NaCl resulted in significant increases in the phosphorylation of p38 MAPK, Akt, and NF-κB and an upregulation of the transcription factors NFAT5 and SGK1. High-salt significantly promotes IL-6 and MCP-1 production by ARPE-19 cells and is associated with activation of the p38 MAPK, Akt, and NF-κB pathway and NFAT-SGK1 pathways.