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

Abstract

To assess whether transcorneal electrical stimulation (TcES) current-dependently slows progressive loss of visual field area (VFA) in retinitis pigmentosa (RP). 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. 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. 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. TcES provides potential for preservation of visual field in patients with RP.