Nilufer Koyluoglu
Liv Hospital International, Turkey.
Title: Artificial vision for later stages of the retinitis pigmentosa with the argus ıı system
Biography
Biography: Nilufer Koyluoglu
Abstract
Retinitis pigmentosa is a degenerative eye disease that causes progressive loss of vision. In RP, there is irreversible degeneration of the outer retina (the photoreceptors) while the inner retinal cells (bipolar cells, retinal ganglion cells) and visual pathway downstream remain intact. Affected people suffer from progressive visual loss which can be profound: 0.5% of people with RP above the age of 45 have no light perception and 25% have ≤1/10 vision in both eyes. A person who suffers with sight loss can experience difficulties relating to maintaining their independence, social isolation, activities of daily living and issues around financial support. Loss of visual field is associated with a decrease in physical mobility and difficulties in adjusting being blind. Treatment options for RP, other than for the associated cataract and macular oedema, are limited. Treatment is mainly aimed at slowing disease progression.
The Argus II system is intended to treat patients at the most advanced stages of RP, for whom there are no other treatment options. It is the only CE-marked and FDA-approved option that can restore vision for end-stage RP patients. The epiretinal prosthesis: Argus II system The Argus II system works by bypassing damaged retinal cells and electrically stimulating retinal ganglion cells, creating visual perceptions (percepts) of light. This is the first example of a system, or any therapy, that has demonstrated improved visual function
in the extremely low-vision range (NLP to HM) in this population. Insertion of an epiretinal prosthesis aims to restore perception of light, movement and shapes by surgically implanting an array of electrodes onto the retina The epiretinal prosthesis has two key components: The eye implant and the external camera system, comprising an eyeglass-mounted video camera and a small patientworn computer (video processing unit, VPU) When the implant is on, the video camera in the patient’s glasses records real-time images and sends them to the VPU. The VPU converts the images into data that are sent back to the glasses and are then wirelessly transmitted to the episcleral receiver unit, which in turn relays the data to the electrode array Electrical impulses are produced which bypass damaged photoreceptors and stimulate the remaining retinal cells. Visual information is then transmitted by the optic nerve to the brain, creating a visual perception. Patient selection must be careful and rigorous and the patient should be counselled to have realistic expectations: if the patient’s expectations of the system are not fulfilled, the patient may stop using the system. To maximise the likelihood that patients receive benefit from the Argus II system, they should be motivated and willing to receive the
recommended training and visual rehabilitation.