Abstract
Purpose: :
To assess effects of transcorneal electrical stimulation (TES) on best corrected visual acuity (BCVA), electroretinography (ERG; Ganzfeld and multifocal=mf) and electrically evoked phosphene threshold (EPT) in patients with Stargardt Disease.
Methods: :
In this prospective, randomized, partially double-blinded study 12 eyes of 12 patients with Stargardt Disease (mean age ± SD: 40.0 ± 9.07 years) and BCVA from 0.04-0.7 were treated with TES (10 ms biphasic current pulses at 20 Hz; applied with DTL electrodes) for 30 minutes once a week for 6 consecutive weeks. Patients were divided into 3 groups according to stimulation strength: 0 (sham), 66% or 150% of individual EPT at 20 Hz (n=4 in each group). Ganzfeld ERGs were recorded according to the ISCEV standards using a ColorDome® controlled by an Espion E2® (Diagnosys LLC, Cambridge, UK). mfERGs were recorded with a VerisTM® (Electro-Diagnostic Imaging Inc., Redwood City; software version Veris ScienceTM 4.9.1) system.
Results: :
No adverse events were observed in the study. There was no statistically significant change in amplitude and latency of the multifocal ERG (P=0.18-0.89), nor in the photopic a- and b-wave amplitudes and implicit times of the ERG (P=0.31-0.97). BCVA of the patients stimulated with 150% improved 0.02 ± 0.01 logMAR (mean ± SE), whereas it decreased - 0.03 ± 0.01 logMAR and - 0.03 ± 0.01 logMAR in the 66% group and in the sham group, resp. (P= 0.07). Sensitivity of electrically evoked phosphenes improved 11.72 ± 2.71 (mean ± SE) in the patients stimulated with 150%, and 1.50 ± 2.65 and 1.25 ± 2.45 in the 66% and sham group, resp. (P= 0.0089).
Conclusions: :
Our data show that TES using DTL electrodes is safe in patients with Stargardt Disease. In (multifocal) ERG no change under treatment was observed in our study. There was a non-significant tendency in the 150% stimulated group for an improvement of BCVA; sensitivity for electrically evoked phosphenes increased significantly in the group treated with 150%. Larger studies with longer duration must be conducted in order to verify results and clarify optimal stimulation parameters.
Clinical Trial: :
http://www.clinicaltrials.gov NCT00804102
Keywords: retinal degenerations: hereditary • electroretinography: clinical • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials