Macular microstructure and visual acuity after macula-off retinal detachment repair by 23-gauge vitrectomy plus silicone endotamponade

Essam Elmatbouly Saber, Ahmed Sherin Mostafa Bayoumy, Mohamed Nagy Elmohamady, Hussam Mustafa Faramawi Department of Opthalmology, Faculty of Medicine, Benha University, Qaliopia, Egypt Objectives: To study the macular microstructural changes and their relationship to visual acuity (VA) following primary vitrectomy and silicone tamponade for retinal detachment. Patients and methods: A total of 40 cases with macula-off rhegmatogenous retinal detachment underwent 23-gauge vitrectomy with silicone oil tamponade. Cases with open globe injury and other ocular pathology were excluded. Optical coherence tomography (OCT) imaging of the macula was done about 3 and 6 months postoperatively. OCT macular microstructural changes were recorded and correlated to VA. Results: A total of 36 eyes were evaluated by statistical analysis. The best-corrected VA (BCVA) improved in 35 patients (97.2%) and remained unchanged in one patient (2.8%). Patients were divided into two groups based on 6-month postoperative BCVA: group I with 6-month postoperative BCVA of <1 LogMAR and group II with 6-month postoperative BCVA of ≥1 LogMAR. No disruption of retinal microstructure occurred in 70% of cases in group I. Mild disruption was found in 30% of group I and 25% of group II, whereas severe disruption was found in 75% of group II cases. Epiretinal membrane formed early in three eyes in group II and late in two eyes in group I. Conclusion: Macular microstructural changes detected by OCT is directly correlated to visual outcomes of retinal detachment repair. Keywords: retinal detachment, vitrectomy, silicone oil, OCT, ellipsoid zone, ER

Hybrid Consensus-Based Formation Control of Nonholonomic Mobile Robots

In this chapter, a hybrid consensus-based formation controller is designed for mobile robots. First, omnidirectional (holonomic) robots are considered in the controller development to create a hybrid automaton, which drives the robots to their goal positions while maintaining a specified formation. The controller consists of two discrete modes, each with continuous dynamics: a regulation mode and a formation keeping mode. The controller in the regulation mode is designed to drive the robot to a goal position, while the formation keeping controller ensures that the robots achieve a specified geometric formation prior to reaching their goal-position. The proposed approach is subsequently extended to include formation control of nonholonomic mobile robots. Lyapunov methods are used to demonstrate that the formation errors converge to a small bounded region around the origin; moreover, the size of the bound can be adjusted by using the switching conditions. Convergence to goal position while in formation is also demonstrated in the same Lyapunov analysis, and simulation results verify the theoretical conjectures