| dc.description.abstract | In this research, we have developed a mathematical model for the electrical
response, measured on the cornea of the human eye for a light pulse. The developed
research establishes the basis for a new model in order to represent the retinal cone and
rod cells behavior in a most precise way, compared against the model proposed by
Usui [1]. Such potentials are described using a set of adaptive filters, and time
variations are easily fixed by calculating the filter weights.
From the developed mathematical models, it is possible to synthesize any action
potential present in the retina with an accuracy of 99.99%. We have also improved the
proposal of several groups of researchers, in order to activate these cells by transcorneal
electrical stimulation (TES). The state of the art in TES up prior to this research,
considered to achieve square bipolar signals for this purpose without ensuring an
adequate response of retinal cell bodies, which are naturally excited by defined ionic
currents, not rectangular pulses as used so far.
The development of stimulation protocols on human cornea, has been reviewed by
medical specialists who follow the international health regulations, helping us achieve
unprecedented results in testing patients for over three years. In these results highlights
the phenomenon known as ʺphosphenesʺ, obtained for applying waveform parameters
as frequency and amplitude never used before.
A collateral effect of the research allowed applying waveforms with previously
defined parameters, to reverse poor vision caused by retinal diseases, such as the
Central Retinal Artery Occlusion (CRAO) and Retinitis Pigmentosa (RP). In this case,
we developed electronic devices capable of generating and controlling the physical
parameters of the unconventional stimulation signal. Signals that have the ability to
‐iiiEstimulador
Eléctrico Transcorneal
emulate the natural potential present on the retinal system when it is stimulated by
light.
First results in this research, helped to know the physical parameters of electrical
signals, which cause a evoked visual sensation by means of not luminous stimulus, thus
allowing us to define the parameters that are biocompatible with the human visual
system. Once established the conditions for biocompatibility of the signal, have
developed protocols for experimental therapy with patients suffering from low vision
caused by CRAO and RP. The experimental results suggest that TES therapy, promotes
the recovery of lost visual skills, using the visual acuity, visual capacity,
electroretinography and visual fields as comparative parameters.
Even with the results of this research, it has not been possible to determine the
mechanisms or alterations suffered by the visual system which allow the recovery of
the capacity of patients. | |
