Transcorneal Electrical Stimulation Dose-Dependently Slows the Visual Field Loss in Retinitis Pigmentosa

PURPOSE: To assess whether transcorneal electrical stimulation (TcES) current-dependently slows progressive loss of visual field area (VFA) in retinitis pigmentosa (RP). METHODS: Data from 51 patients with RP who received monocular TcES treatment once weekly over 1 year in an interventional, randomized study have been analyzed a posteriori. Current amplitudes were 0.1 to 1.0 mA in the TcES-treated group (n = 31) and 0.0 mA in the sham group (n = 20). VFA was assessed in both eyes (semiautomatic kinetic perimetry, Goldmann targets V4e, III4e). Annual decline rate (ADR) of exponential loss and model-independent percentage reduction of VFA at treatment cessation were correlated to current amplitude. RESULTS: For V4e, mean ADR was −4.1% in TcES-treated eyes, −6.4% in untreated fellow eyes, and −7.2% in placebo-treated eyes; mean VFA reduction in TcES-treated eyes was 64% less than in untreated fellow eyes (P = 0.013) and 72% less than in placebo-treated eyes (P = 0.103). Individual VFA reductions correlated with current amplitude (P = 0.043) and tended toward zero in patients who received 0.8 to 1.0 mA. For III4e, there was a marginally significant current-dependency of interocular difference in reduction (P = 0.11). ADR and VFA reduction did not significantly correlate with baseline VFA. CONCLUSIONS: Loss of VFA (V4e) in patients with RP was significantly reduced in treated eyes compared to untreated eyes by regular use of TcES in a dose-dependent manner. No dependence of effects on the initial extent of VFA loss was found. TRANSLATIONAL RELEVANCE: TcES provides potential for preservation of visual field in patients with RP.