Lamellar macular holes: evolving concepts and propensity for progression to full thickness macular hole

Currently the term lamellar macular hole (LMH) alludes to a wide spectrum of macular conditions including distinct clinical entities with different pathomorphologies. Classifications into subtypes, tractional and degenerative or based on the associated preretinal tissue had been proposed. Recent insights suggest that only lesions with tissue loss should be considered ‘true’ LMH and not those morphological changes caused by tractional forces. Inclusion of lesions with foveoschisis with contractile epiretinal membrane (ERM) in earlier studies on LMHs has resulted in imprecise information about its clinical course. This review provides an overview of the evolving concepts of LMHs and analyses its natural history from study cases in previously published literature.

Coupling of Fibrin Reorganization and Fibronectin Patterning by Corneal Fibroblasts in Response to PDGF BB and TGFβ1

We previously reported that corneal fibroblasts within 3D fibrin matrices secrete, bind, and organize fibronectin into tracks that facilitate cell spreading and migration. Other cells use these fibronectin tracks as conduits, which leads to the development of an interconnected cell/fibronectin network. In this study, we investigate how cell-induced reorganization of fibrin correlates with fibronectin track formation in response to two growth factors present during wound healing: PDGF BB, which stimulates cell spreading and migration; and TGFβ1, which stimulates cellular contraction and myofibroblast transformation. Both PDGF BB and TGFβ1 stimulated global fibrin matrix contraction (p < 0.005); however, the cell and matrix patterning were different. We found that, during PDGF BB-induced cell spreading, fibronectin was organized simultaneously with the generation of tractional forces at the leading edge of pseudopodia. Over time this led to the formation of an interconnected network consisting of cells, fibronectin and compacted fibrin tracks. Following culture in TGFβ1, cells were less motile, produced significant local fibrin reorganization, and formed fewer cellular connections as compared to PDGF BB (p < 0.005). Although bands of compacted fibrin tracks developed in between neighboring cells, fibronectin labeling was not generally present along these tracks, and the correlation between fibrin and fibronectin labeling was significantly less than that observed in PDGF BB (p < 0.001). Taken together, our results show that cell-induced extracellular matrix (ECM) reorganization can occur independently from fibronectin patterning. Nonetheless, both events seem to be coordinated, as corneal fibroblasts in PDGF BB secrete and organize fibronectin as they preferentially spread along compacted fibrin tracks between cells, producing an interconnected network in which cells, fibronectin and compacted fibrin tracks are highly correlated. This mechanism of patterning could contribute to the formation of organized cellular networks that have been observed following corneal injury and refractive surgery.

Coupling of Fibrin Reorganization and Fibronectin Patterning by Corneal Fibroblasts in Response to PDGF BB and TGFβ1

We previously reported that corneal fibroblasts within 3D fibrin matrices secrete, bind, and organize fibronectin into tracks that facilitate cell spreading and migration. Other cells use these fibronectin tracks as conduits, which leads to the development of an interconnected cell/fibronectin network. In this study, we investigate how cell induced reorganization of fibrin correlates with fibronectin track formation in response to two growth factors present during wound healing: PDGF BB, which stimulates cell spreading and migration; and TGF&beta;1, which stimulates cellular contraction and myofibroblast transformation. Both PDGF BB and TGFb1 stimulated global fibrin matrix contraction (P &lt; 0.005), however cell and matrix patterning were different. We found that during PDGF BB induced cell spreading, fibronectin was organized simultaneously with the generation of tractional forces at the leading edge of pseudopodia. Over time this led to the formation of an interconnected network consisting of cells, fibronectin and compacted fibrin tracks. Following culture in TGF&beta;1, cells were less motile, produced significant local fibrin reorganization, and formed fewer cellular connections as compared to PDGF BB (P &lt; 0.005). Although bands of compacted fibrin tracks developed in between neighboring cells, fibronectin labeling was not generally present along these tracks, and the correlation between fibrin and fibronectin labeling was significantly less than that observed in PDGF BB (P &lt; 0.001). Taken together, our results show that cell-induced ECM reorganization can occur independently from fibronectin patterning. Nonetheless, both events seem to be coordinated, as corneal fibroblasts in PDGF BB secrete and organize fibronectin as they preferentially spread along compacted fibrin tracks between cells, producing an interconnected network in which cells, fibronectin and compacted fibrin tracks are highly correlated. This mechanism of patterning could contribute to the formation of organized cellular networks that have been observed following corneal injury and refractive surgery.

Comparative Evaluation of Biomechanical Performance of Titanium and Stainless Steel Mini Implants at Different Angulations in Maxilla: A Finite Element Analysis

Objective: To assess and compare the tensions and deformations (stresses and strains) generated after application of two types of forces (traction and torsion) in miniscrews of two different materials (titanium and stainless steel) placed at five different angulations. Materials and Methods: Three-dimensional models of the posterior maxillary area and the mini-implants were constructed using computer-aided design software program (CATIA P3 V5-6 R2015 B26 / 2016; Dassault Systèmes). Titanium and stainless steel materials were used for miniscrews. The area constructed was in between the maxillary second premolar and first molar. The models with mini-implants were inserted at five different angulations (30°, 45°, 60°, 75° and 90°). Torsional and tractional forces were applied on these implants, and the models were solved using ANSYS 10.0. Stress generated in implant and in the cortical and cancellous bones was evaluated and compared at all the five angulations. Results: Stress generated in stainless steel mini-implant during torsional and linear force application was less when compared with titanium mini-implant. Also, stress generated in implants of both materials increased as the angle increased from 30° to 90°. Difference in stress generated by stainless steel implant in the cortical bone for both linear and torsional forces was less when compared with titanium implant, whereas for cancellous bone, the difference was insignificant at all the angles. Conclusion: Irrespective of angles, difference in stress generated in stainless steel implants and titanium implants for both the forces was not significant, and hence, stainless steel implants can be used effectively in a clinical setting.

Pathogenesis and Management of Macular Hole: Review of Current Advances

Macular hole has been believed to be a disorder of vitreomacular interface, which forms as a result of abnormal vitreous traction from incomplete vitreous detachment. However, our recent studies demonstrated that dynamic forces, caused by mobile posterior cortical vitreous with fluid currents, exist already at early stages of macular hole development. Therefore, in eyes with flexible vitreous, the contributions of tractional forces due to vitreous shrinkage are unlikely. These facts indicate that in the development of idiopathic macular holes, there is a greater contribution of dynamic forces than has been previously reported. This review also evaluates the recent findings in the assessment of the idiopathic macular holes and the recent therapeutic strategies for optimal management. Inner limiting membrane is considered to improve anatomical closure rate; however, it is still questionable if peeling is necessary in holes less than 250 µm. There are plenty of publications indicating that in the management of small and medium size hole (less than 400 µm), use of long-lasting gas and face-down position is not always required; however, it may be necessary for the treatment of large holes. Ocriplasmin and expansile gas had been reported to be successful for management of small- and medium-sized holes and vitreomacular attachment.

Macular Hole in Myopic Eyes: A Narrative Review of the Current Surgical Techniques

Macular hole (MH) in myopic eyes is a disease arising from complex tractional forces exerted by vitreomacular interface, epiretinal tissue, and progressive scleral ectasia of the posterior ocular globe wall. This retinal disease requires vitreoretinal treatment for its repair, and the surgical intervention remains a challenge also for experienced surgeons. The aim of this review is to describe the current knowledge regarding the pathogenesis of MH in myopic eyes and to detail novel surgical techniques and technological advancements in its surgical management.