Subject: Current stimulation to the brain partially restores vision in patients
with glaucoma and optic nerve damage: Randomized, clinical trial shows that
modulating brain plasticity offers a promising avenue for vision restoration and
rehabilitation
Current stimulation to the brain partially restores vision in patients with
glaucoma and optic nerve damage: Randomized, clinical trial shows that
modulating brain plasticity offers a promising avenue for vision restoration and
rehabilitation
ScienceDaily
Vision loss due to glaucoma or optic nerve damage is generally considered
irreversible. Now a new prospective, randomized, multi-center clinical trial
demonstrates significant vision improvement in partially blind patients after 10
days of noninvasive, transorbital alternating current stimulation (ACS). In
addition to activation of their residual vision, patients also experienced
improvement in vision-related quality of life such as acuity, reading, mobility
or orientation. The results are reported in PLOS ONE.
"ACS treatment is a safe and effective means to partially restore vision after
optic nerve damage probably by modulating brain plasticity, re-synchronizing
brain networks, which were desynchronized by vision loss.
This class 1 evidence is the first ever large-scale multi-center clinical trial
in the field of non-invasive brain modulation using electric currents and
suggests that visual fields can be improved in a clinically meaningful way,"
commented lead investigator Bernhard A. Sabel, PhD, of the Institute of Medical
Psychology, Medical Faculty, Otto-von-Guericke University of Magdeburg
(Germany).
In a study conducted at three German clinical centers (University of Göttingen,
Charité Berlin, and University of Magdeburg), 82 patients were enrolled in a
double-blind, randomized, sham-controlled clinical trial, 33 with visual
deficits caused by glaucoma and 32 with anterior ischemic optic neuropathy
caused by inflammation, optic nerve compression (due to tumors or intracranial
hemorrhage), congenital anomalies, or Leber's hereditary optic neuropathy. Eight
patients had more than one cause of optic nerve atrophy.
The groups were randomized so that 45 patients underwent 10 daily applications
of ACS for up to 50 minutes per day over a two-week period and
37 patients received sham stimulation. The only difference between groups before
treatment was that the stimulation group included more men than the sham group;
no other differences were found, including age of the lesion or visual field
characteristics. ACS was applied with electrodes on the skin near the eyes.
Vision was tested before and 48 hours after completion of treatment, and then
again two months later to check if any changes were long-lasting.
Patients receiving ACS showed significantly greater improvements in perceiving
objects in the whole visual field than individuals in the sham-treated group.
Specifically, when measuring the visual field, a 24% improvement was noted after
treatment in the ACS group compared to a 2.5% improvement in the sham group.
This was due to significant improvements in the defective visual field sector of
59% in the ACS group and 34% in the sham group which received a minimal
stimulation protocol. Further analyses showed improvements in the ACS group at
the edges of the visual field. The benefits of stimulation were found to be
stable two months later, as the ACS group showed a 25% improvement in the visual
field compared to negligible changes (0.28%) in the sham group.
Patient safety measures were maintained at a high level, in line with previous
studies. Current flow was assessed using sophisticated computer simulation
models. No participants reported discomfort during stimulation, although
temporary dizziness and mild headaches were reported in rare cases.
The study results are in line with previous small sample studies in which
efficacy and safety were observed. Those studies revealed that well-synchronized
dynamic brain functional networks are critical for vision restoration. Although
vision loss leads to de-synchronization, these neural networks can be
re-synchronized by ACS via rhythmic firing of the ganglion cells of the retina,
activating or "amplifying" residual vision. Dr. Sabel added that "while
additional studies are needed to further explore the mechanisms of action, our
results warrant the use of ACS treatment in a clinical setting to activate
residual vision by brain network re-synchronization. This can partially restore
vision in patients with stable vision loss caused by optic nerve damage."
In summary, vision loss, long considered to be irreversible, can be partially
reversed. There is now more light at the end of the tunnel for patients with low
vision or blindness following glaucoma and optic nerve damage.
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