·Age-related macular degeneration (AMD) and retinitis pigmentosa (RP) are common outer retinal degenerative problems, which are also the predominant causes of most blinding retinal diseases. Retinal prosthesis is a promising solution for such photoreceptor degeneration diseases.Most of current concepts for a retinal prosthesis are based on neuronal electrical stimulation. In the past twenty years, retinal prosthesis has been developed in two different directions: epiretinal prosthesis and subretinal prosthesis. Each prosthesis technique has its advantages and disadvantages. For epiretinal prosthesis, it is easier to be implanted and has the advantage of keeping most of the electronics in the vitreous cavity, off the retinal surface, which greatly helps in dissipating the heat generated by the implant device. In this paper, a brief overview of retinal prostheses concepts is introduced. After that, several important aspects of epiretinal electrical stimulation will be discussed. Moreover, some practical epiretinal prosthesis devices developed by researchers in United States, Germany and Japan in the past have been reviewed. We hope that the devices will be used widely in the near future.

Objective To investigate the occurrence and risk factors of vascular access infection(VAI) in hemodialysis outpatients.Methods Prospective surveillance method,monitoring methods was formulated and adopted by referring to the relevant guidelines and regulations at home and abroad,targeted surveillance was performed among all outpatients receiving hemodialysis in a hospital from June 1,2014 to May 31,2016.Results A total of 584 outpatients received hemodialysis from June 1,2014 to May 31,2016,with 64 203 times of vascular access,79 patients developed 85 cases of infection,case incidence of VAI was 1.32％.36 cases(42.35％) were infection at vascular puncture sites,49 (57.65％) were vascular access-related bloodstream infection.Among patients with different types of vascular access,incidence of VAI was the highest among patients with artificial vascular graft(19.67％),followed by those with non tunneled central venous catheter(4.91％),with tunneled central venous catheter (0.73％),and with arteriovenous fistula(0.09％).Age＞ 60 years,hemodialysis time＞ 1 year,diabetes,and hypertension were risk factors for VAI in outpatients with hemodialysis(all P＜0.05).39 strains of pathogens were isolated from 49 patients with vascular access-related bloodstream infection,including 36 (92.31％) gram positive bacteria,mainly Staphylococcus aureus (n =30,6 of which were methicillin-resistant Staphylococcus aureus);3 (7.69 ％) gram-negative bacteria.Conclusion Strengthening prospective targeted surveillance can better understand the status,characteristics,and risk factors of VAI in hemodialysis outpatients,it is conducive to taking targeted prevention and control measures,thus reduce the incidence of VAI in hemodialysis outpatients.