Transcorneal electrical stimulation therapy for glaucomatous optic neuropathy

Abstract

PURPOSE: To examine the efficacy of transcorneal electrical stimulation (TES) in enhancing the function of the optic nerve in glaucomatous optic neuropathy - To document any side effects arising from TES to treat a chronic eye disease METHODS: Adult patients were recruited in one hospital in Hong Kong. Patients with bilateral glaucomatous optic neuropathy of similar degree, as determined by optic disc morphology, Humphrey visual field (VF) and/or optical coherence tomography (OCT) were recruited. Any form of glaucoma was included. One eye was randomized to receive TES (treatment arm) by drawing envelop, and the other eye would automatically be in the control arm. Each patient received TES for a period of 30 minutes once per week over 26 weeks. The studied parameters, including visual acuity, intraocular pressure, anterior segment and posteior segment examination with microscopy, VF, OCT for retinal nerve fibre layer (RNFL) and electroretinography (ERG) using multifocal ERG, were measured once at baseline, every 3 months during the study period, and at 3 and 6 months after the last stimulation. OUTCOME MEASURES: Primary outcome: VF, ERG signal Secondary outcomes: RNFL thickness RESULTS: Forteen patients were enrolled into the study and three of them completed at least 3 months treatment and investigations at the time of report. The 3 patients were from 63-76 years old, 2 males and 1 female. Regarding the VF, all patients demonstrated improvement in at least one of the parameters (median deviation and visual field index) in the treatment eye at 3 months post-treatment as compared to the baseline. In 2 of the patients, both parameters improved. In contrast, in all the 3 patients, the fellow control eye did not show any improvement in any one of the VF parameters. (Table 1) All 3 patients also showed improvement in at least 3 out of the 4 ERG signal parameters. (Table 2) OCT findings were inconsistent. There were no side-effects reported by any patient during the treatment. CONCLUSIONS: Preliminary data on our glaucoma patients demonstrated potential benefit of TES in terms of improvement in VF and ERG signal. TES can be a promising novel treatment for glaucomatous optic neuropathy. Further studies on the exact duration, pulse duration and current density to achieve maximal benefit would be neccessary.