Abstract
Purpose: :
Transcorneal electrical stimulation (TES) has been claimed beneficial in several ocular diseases such as retinal artery occlusion and optic nerve damage. This prospective, randomized, partially-blinded, good-clinical-practice conform study explored the safety and efficacy of TES in patients with retinitis pigmentosa (RP) by a variety subjective and objective parameters of visual function.
Methods: :
Twenty-four patients received TES (5 ms biphasic pulses; 20 Hz; DTL electrodes) 30 minutes per week for 6 consecutive weeks. Patients were randomly assigned to one of three groups: sham, 66%, or 150% of individual electrical phosphene threshold (EPT). Visual acuity (VA), visual field (VF; kinetic, static), electroretinography (Ganzfeld, multifocal), dark-adaptation, color discrimination, and EPTs were assessed at all visits or 4 times according to the study plan.
Results: :
TES using DTL electrodes was tolerated well; all patients concluded the study. Two adverse (foreign body sensation) but no serious adverse events were encountered. There was a tendency for most functional parameters to improve (8/18) or remain constant (8/18) in the 150% group. The scotopic b-wave amplitude changed by 8.79 µV, -8.82, and -8.43 µV in the 150%, 66%, and sham group, resp. (P=0.027). Visual field area changed by 17%, -9%, and -6% in these groups, resp. (P<0.001). Only desaturated color discrimination and VF mean sensitivity decreased (the latter due to the enlargement of VF area). There was no obvious trend in the 66% group.
Conclusions: :
We have found TES in RP patients safe. Positive trends were discovered, but due to the small sample size of this pilot study statistical significance was only reached for VF area and scotopic b-wave amplitude. Further studies with larger sample sizes and longer duration are needed to confirm findings and to define optimal stimulation parameters.
Clinical Trial: :
http://www.clinicaltrials.gov NCT00804102
Keywords: retinal degenerations: hereditary • growth factors/growth factor receptors