About the Method of Therapeutic Electrical Stimulation
The application of electrical stimulation therapy (repetitive transorbital alternating current stimulation) is based on the potential of the vision system to adapt to functional and structural changes that can be induced by external influence, for example, by using electric current impulses. Clinical experience has shown that if such activation is performed for several weeks then it can cause significant changes (induced plasticity of visual system) in the functional state (activation) of the entire brain vision system.
In instances of vision deterioration induced by optic nerve and retinal diseases, such as plasticity of the vision system, intervention is strongly needed to restore vision. By decreasing the defects of visual fields or eliciting the enlargement of preserved areas of vision and increasing vision acuity we can encourage a normal quality of vision. Such results can be achieved through therapeutic electrical stimulation that activates the retinal ganglion cells, enhances the signal conductivity through visual pathways (including optic nerve), and embodies the visual cortex reserves, resulting in an optimal functional state of the whole brain and improving the vision system. Treatment by properly adjusted impulses (electric current therapy) focuses on non-invasive electrical activation of retinal neurons using impulses with different shapes and amplitudes through electrodes located around the eyes (periorbitally).
Retinal neurons have an essential role in the functioning of the visual system. One one side of the brain they obtain information using extensions, called axons, through the optic nerve, relaying this information to the rest of the brain. On the other side, ganglion cells receive signals from receptors (cones and rods) coding information on the environment.
From a practical point of view the application of therapeutic electrical stimulation includes selection of optimal impulses which can evoke artificial visual effects such flickers, flashes or more complex light effects in the patients as a result of the effect on retinal ganglion cells. Their presence is the result of the activation of cortical visual centers located in occipital lobes of both hemispheres. External electrical signals applied to the retina can induce functional activity in the visual cortex (prestriate area) located deep in the brain.
Activated neurons of visual centers can better analyze information obtained from the retina, which were reduced by optic nerve damage causing a descending activating effect on ganglion cells, therefore, creating conditions for vision improvement. Similarly, the photo camera matrix extends the diaphragm in low light situations.
During the treatment process the conduction visual pathways (optic nerves, tracts, central visual pathway) are activated both from periphery by retinal ganglion cells and from the top by the neurons of the occipital cortex. The method of therapeutic electrical stimulation was developed.by taking into account that such organization of the visual system includes the interaction of center and periphery, cells and their axons, and forming a new connectivity between different brain structures.
Stability of the treatment results is achieved mostly due to the therapeutic electrical stimulation inducing plastic changes in the vision system. These changes mainly occur in the visual cortex given that functional abilities and plasticity of neurons of visual cortex are much higher than that of lesioned optic nerve fibers or even damaged retinal neurons (first of all ganglion cells). This achieves activation of the vision centers allowing for significant optimization of visual processing to occur. These results, combined with the elicited activation of retinal ganglion cells, is the basis to achieve the stable effects of partially or permanently restored vision.
Principles of therapeutic electrical stimulation
Our long-term experience in the treatment and care of visually impaired patients as well as accumulated knowledge in the development of medical approaches allows us to establish the principles to which therapeutic electrical stimulations should correspond:
Who Can Benefit
Indications for treatment include different forms of vision deterioration manifested by a decrease in vision acuity, different types of visual fields defects or their combination. According to etiology (the cause of vision loss) the following diseases and consequences are indications for treatment:
I. Optic nerve damage (optic neuropathy, optic nerve atrophy) caused by:
- Glaucoma (glaucomatous optic neuropathy)
- Ischemic lesion (anterior arterial and non-arterial ischemic neuropathy)
- Central retinal artery occlusion
- Traumatic injuries (traumatic optic nerve atrophy or traumatic optic neuropathy)
- Brain tumor or non-tumor mass (including cysts, etc.)
- Neuromyelitis optica
- Optic neuritis by multiple sclerosis
- Leber’s atrophy and autosomal dominant optic neuropathy (genetically determined disease of the optic nerve leading to optic neuropathy)
- Toxic damages of the optic nerve
- As a result of antenatal or postnatal lesions (congenital optic nerve atrophy)
- Optic disc drusen (ODD) or optic nerve head drusen (ONHD)
II. Lesion of visual pathway in the brain (chiasm, optic tract, optic radiation), as well as the visual cortex in the occipital hemispheres of the brain due to:
- ischemic stroke
- cerebral hemorrhage
- traumatic injuries
- inflammatory processes
III. Mono- or bilateral amblyopia (lazy eye)
IV. Diseases of the retina:
- retinitis pigmentosa
- Stargardt’s macular degeneration
- Age related macular degeneration
- dystrophic chorioretinitis (for myopia)
- angiopathy, or the initial stage of retinopathy in diabetes
V. Hemianopia after the stroke, trauma or brain tumor
VI. Myopia (near-sightedness or short-sightedness) as a combination with dystrophic chorioretinitis
In many cases the method of therapeutic electrical stimulation can help to restore vision and will be performed in an optimum individual manner taking into account functional abilities of the vision system and brain. This course of treatment is decided on a case-by-case basis to ensure success.
Limiting factors to improve vision with therapeutic electrical stimulation
Treatment analysis in more than 600 patient cases showed that the leading factors in significantly limiting the ability to improve sight are:
- Blindness or only light perception
- The cause of optic nerve lesion is not completely eliminated, as in uncompensated hydrocephalus or multiple sclerosis with frequent attacks causing new optic neuritis
- Severe morphological lesions of retina
- Visual impairments caused by profound (severe) anatomical lesions of brain structures
- Long lasting vision loss combined with severe vision deterioration.
In such cases our treatment will be used as an attempt to achieve changes of sight. Taking into account that, even in cases of severe vision deterioration or in the absence of formal vision, 10 to 15% of our patients have an ability to achieve some positive dynamics, we cannot completely exclude the advisability of conducting a stimulation course.
Application of electrical stimulation treatment incurs some risks of side effects. The following patient’s conditions and states are referred to in this category:
When therapy for vision loss is not indicated
The method of electrical stimulation treatment is not recommended for eyesight deficit caused by:
- cataract or pathology of cornea
- age related diminished ability to focus on near objects (presbyopia)
- astigmatism or hyperopia
- visual impairments caused by retina hemorrhages, detachment or swelling
- vision deterioration due to diabetic retinopathy with the hemorrhages
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