ABSTRACT
PURPOSE: Partial blindness after visual system damage is considered irreversible, yet the brain has residual visual capacities and considerable plasticity potential. We now applied non-invasive alternating current stimulation (ACS) to the visual system of patients with optic nerve damage with the aim to induce recovery of visual functions. METHODS: In a prospective, double-blind, randomized, placebo-controlled clinical trial patients with several year old partial optic nerve lesions were treated with ACS (n = 12) or placebo-stimulation (n = 10). ACS was delivered transorbitally for 40 minutes on 10 days. Visual outcome measures and EEG were measured before and after treatment. RESULTS: ACS, but not placebo, led to significant improvement of a visual field detection deficit by 69%, and also significantly improved temporal processing of visual stimuli, detection performance in static perimetry, and visual acuity. These changes were associated with alpha-band changes in the EEG power spectra. Visual improvements were stable for at least 2-months. CONCLUSIONS: ACS can induce vision restoration many years after optic neuropathy. Though the mechanism is still unclear, EEG changes indicate increased synchronization in posterior brain regions. The present study provides Class Ib evidence that non-invasive transorbital ACS is well tolerated and improves visual function in optic neuropathy.
Subject(s)
Electric Stimulation/methods , Evoked Potentials, Visual/radiation effects , Optic Nerve Diseases/therapy , Vision, Ocular/radiation effects , Visual Fields/radiation effects , Adult , Aged , Double-Blind Method , Electrodes , Electroencephalography , Evoked Potentials, Visual/physiology , Female , Follow-Up Studies , Humans , Male , Middle Aged , Prospective Studies , Treatment Outcome , Visual Field Tests , Visual Fields/physiologyABSTRACT
BACKGROUND: Visual field defects after optic nerve damage typically show a limited capacity for spontaneous and treatment-induced recovery. OBJECTIVE: Repetitive transorbital alternating current stimulation (rtACS) was applied to the damaged optic nerve to evaluate visual functions after stimulation. METHODS: A 27-years-old male patient suffering left optic nerve atrophy with nearly complete loss of vision 11 years after atypical traumatic damage was treated transorbitally with biphasic 10-15 pulse trains of rtACS (10-30 Hz, < 600 µA, 30-40 min daily for 10 days) which produced phosphenes. RESULTS: After rtACS treatment detection ability of super-threshold stimuli increased from 3.44% to 17.75% and mean perimetric threshold from 0 dB to 2.21 dB at final diagnostics. CONCLUSION: This improvement of vision may be due to increased neuronal synchronization, possibly involving strengthening of synaptic transmission along the central visual pathway.
