Neurotransmission in Visual Analyser and Bionic Eye. A Review

Abstract

Aims: The aim of the work is to point out the transmission of electrical voltage changes in the visual analyser and thus the efficiency of the bionic eye. Material and methods: The review deals with the question of the transmission of electrical changes in visual path voltage under physiological and pathological conditions. In particular, it points to feedback autoregulatory damage not only of primarily altered cellular structures, but of all other, both horizontally and vertically localized. Based on the results of functional magnetic resonance imaging and electrophysiological methods, it shows the pathology of the entire visual pathway in three eye diseases: retinitis pigmentosa, age-related macular degeneration and glaucoma. Results: The thesis also provides an overview of possible systems that are used to replace lost vision, from epiretinal, subretinal, suprachoroidal implants, through stimulation of the optic nerve, corpus geniculatum laterale to the visual cortex. Conclusion: Due to the pathology of neurotransmission, bionic eye systems cannot be expected to be restored after stabilization of binocular functions.

Visual neuroprosthesis: present and future perspectives

“…This disease is most commonly indicated for implantation of the visual neuroprosthesis. Similar destruction occurs in hypertensive glaucoma, where primarily retinal ganglion cells are damaged 3 .…”

“…Any retinal nerve cell lesion can damage not only cellular structures located horizontally, but also vertically in the visual pathway. Another important finding resulting from this information as well as from the visual pathway anatomy is that unilateral lesions also cause damage to the contralateral nerve structures 3 . Therefore, it is not possible to predict improvement of visual functions to usable values when implanting a visual neuroprosthesis.…”

“…The electrophysiological examination showed a mutually unfavourable response, both ERG and PERG and PVEP (ref. 3 ).…”

Visual Neuroprosthesis – Stimulation of Visual Cortical Centers in The Brain. Design of Non-Invasive Transcranial Stimulation of Functional Neurons

“…Sítnicové abnormality (dystrofie, degenerace sítnice, glaukom a jiné) vedoucí k těžké poruše zrakových funkcí nejsou lokalizovány jen do jejich primárně poškozených buněčných struktur, ale poškozují i další struktury včetně zrakové dráhy a zrakového korového ústředí v mozku. Proto snahy o obnovu zrakových funkcí neuroprotézou na úrovni oka (epiretinální, subretinální, suprachoroidální či intrasklerální) nemohou mít dosažitelný efekt [1,2].…”

“…Většina z nich stimuluje jen primární (V1) nebo asociační zraková centra (V2, V3). Dle našich zkušeností jsou právě tato centra anterográdními sítnicovými procesy poškozena [1,2,[36][37][38][39][40][41].…”