Abstract
Purpose :
Transcorneal electrical stimulation (TES) may rescue axotomized retinal ganglion cells through upregulation of endogenous neurotrophic factors. An initial pilot study assessing TES in participants with retinitis pigmentosa (RP) identified improvements in kinetic perimetry and scotopic electroretinography function. We report the results of the TESOLAUK study, which explored the impact and safety of TES in participants with RP.
Methods :
Fourteen trial participants, aged 18 – 79 with confirmed rod-cone dystrophy were recruited at two university hospitals into an open-label observational trial for one year (NCT01847365). Participants with other ocular diseases were excluded as part of the protocol. Assessments occurred at baseline and each three months thereafter. Each assessment visit incorporated slit lamp examination, applanation tonometry, optical coherence tomography (OCT) and autofluorescence. Visual function was assessed with Goldmann visual fields (GVF) and microperimetry (MP). Weekly TES was administered by the Okustim® device for six months to one eye. The current administered was 150% of the threshold upon which the individual first perceived central phosphenes (individual phosphene threshold, IPT).
Results :
All participants tolerated TES well with no serious adverse effects noted. Two of fourteen participants withdrew from the study due to personal reasons during the observation period. After six months of TES, mean change in 10-2 MP threshold sensitivity was +0.02±1.93 dB for the control and +0.37±1.53 dB for the treated eye (p=0.61). Mean GVF volumes were +0.16±0.32 steradians for the control and +0.22±0.45 for the treated eye steradians (p=0.66).
Conclusions :
TES demonstrated a favorable side effect profile with the most common adverse effect being a transient foreign body sensation and ocular irritation. Although there was a numerical increase in both GVF and MP, it was not statistically significant. Subsequent studies should investigate the impact of TES in specific RP genotypes, its impact over a longer period and whether adjustment of the delivered current may promote improvement.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.