Abstract
Optic nerve injury induces a loss of vision which proceeds rapidly within several hours, together with retinal ganglion cell death in much slower time course. Electrical stimulation has previously been shown to rescue the injured retinal ganglion cells from cell death. It is not clear whether electrical stimulation is effective for acute impairment of visual function. We tested whether transcorneal electrical stimulation could preserve visual function after an optic nerve crush. Transcorneal electrical stimulation was given immediately after a calibrated optic nerve crush. We measured visually evoked potential (VEP) in the visual cortex of rats before, immediately after the optic nerve crush, and after the transcorneal stimulation to estimate an extent of damage and effects of stimulation in individual animals. In addition, we labeled the retinal axons with a fluorescent anterograde tracer to determine whether the transcorneal electrical stimulation can protect the retinal axons from degeneration. The optic nerve crush was made at an intensity that does not allow a spontaneous recovery of VEP for 1 week. The transcorneal stimulation immediately increased VEP amplitude impaired by the optic nerve crush and this augmentation was often preserved after one week. In the stimulated animals, a larger amount of retinal axons projected centrally beyond the crushed region in comparison to the unstimulated animals. Transcorneal electrical stimulation would restore the functional impairment of optic nerve by traumatic injury at an early stage and protect retinal axons from the following degeneration. [J Physiol Sci. 2007;57 Suppl:S29]
