I decided to write this article after reading quite sad notification dedicated to a patient whose cornea was restored after longstanding blindness. In spite of operation successfulness, researchers observing the patient during 7 months after the operation, concluded that due to long-term visual deprivation the vision restoration may never be complete.
According to the theory, the visual system pathway usually is not damaged totally. There still exist some survived residual structures. Nevertheless they can’t provide proper transfer of visual information because the neuronal cell loss leads to neuronal network disorganization, i.e. to loss of network synchrony. Stimulation with rtACS forces the disorganized neuronal network to fire simultaneously. That restores the network synchrony of both survived cells within damaged region and cells of upstream visual pathway. Repetition of rtACS stimulation stabilizes the network firing synchrony. The mechanism involved is similar to one underlying the process of normal learning.
According to Dr. Sabel, the subject’s age, as well as age, type and location of the damage throughout visual system pathway do not influence the degree of visual restoration (it refers to injuries of nerve tissues, that is retina, optic nerve, brain regions). The only known parameter that matters for restoration, though, is the size and topography of areas of residual vision (ARVs). Vision restoration may be induced in most visual field impairments (scotoma, tunnel vision, hemianopia, acuity loss), irrespective of their etiology (e.g. stroke, neurotrauma, glaucoma, amblyopia, age-related macular degeneration). However, vision restoration is rarely complete and does not take place in all patients.