Overview of Visual Prostheses

Introduction: Ophthalmic diseases such as retinal dystrophies (retinitis pigmentosa), glaucoma, etc., damage eyesight and as a result leave the patient partially or fully blind. This is due to the destruction of different types of cells in the retina - photoreceptor cells, bipolar neurons, amacrine neurons and others. Recent developments in biomechanical engineering and surgery have enabled us to implant prostheses in the retina, optic nerve and visual cortex thus enabling us to manually send electrical impulses to the respective parts of the visual pathway. Using these methods, clinical trials throughout have shown partial restoration of sight measured by improvement in basic object recognition, motion detection, letter and word reading under specific conditions.Materials and Methods: The information for this scientific overview was gathered using the search engine of PubMed and the keywords: bionic, eye, retinal, prostheses, eyesight. The articles used in this review were all written after the year 2012 and have been published in peer-reviewed journals with impact factor.Results: Depending on the specific damage sustained by the visual pathway, there are several types of prostheses that could be implanted in the patient. Some of the most frequently used are Argus I, Argus II, the Learning Retinal Implant system (LRI) and the EPI-RET3 Implant. All of them have been used in clinical trials and have improved different aspects of the patients` eyesight.Conclusion: Development of visual prostheses has come a long way and is used today to partially restore several aspects of the patients` vision. There are still factors limiting the capabilities of the different types of prostheses. However, with the rapid development of biomechanical engineering and the surgical practice these factors are sure to be surpassed in the near future