Transcorneal electrical stimulation promotes survival of photoreceptors and improves retinal function in rhodopsin P347L transgenic rabbits.

Purpose: To determine whether transcorneal electrical stimulation (TES) has neuroprotective effects on the photoreceptors, and whether it slows the rate of decrease of the electroretinogram (ERG) in rhodopsin P347L transgenic (Tg) rabbits.
Methods: Six-week-old Tg rabbits received TES through a contact lens electrode on the left eye weekly for 6 weeks. The right eyes received sham stimulation on the same days. Electroretinograms (ERGs) were recorded before and at 12 weeks after the TES. After the last ERG recordings, the animals were euthanized for morphologic analysis of the retinas. Immunohistochemical (IHC) analysis was performed to detect the immunostaining by peanut agglutinin (PNA) and rhodopsin antibodies in the retinas.
Results: The a- and b-wave amplitudes of the photopic ERGs and the b-wave amplitudes of the scotopic ERGs at higher stimulus intensities were significantly larger in the TES eyes than in the sham stimulated eyes (P<0.05, respectively). Morphologic analyses showed that the mean thickness of the outer nuclear layer (ONL) in the visual streak at 12 weeks was significantly thicker in TES eyes than in sham-stimulated eyes (P<0.05). IHC showed that the immunostaining by PNA and rhodopsin antibody in the TES-treated retinas was stronger than that in the sham-stimulated retinas.
Conclusions: TES promotes the survival of photoreceptors and preserves the ERGs in Tg rabbits. Although further investigations are necessary before using TES on patients, these findings indicate that TES should be considered for therapeutic treatment for RP patients with a P347L mutation of rhodopsin.