Abstract
Purpose: :
To assess the safety and efficacy of transcorneal electrical stimulation (TES) in patients with nonarteritic anterior ischemic optic neuropathy (NAION).
Methods: :
13 patients with NAION (8 m, 5 w, age 53-76 yrs) were enrolled in the study. NAION was diagnosed 1 week to 12 months prior to study participation. Patients were treated with TES (5 ms + 5 ms biphasic pulses at 20 Hz; applied with DTL electrodes and a neurostimulator Twister® (Dr. Langer GmbH, Germany)) for 30 minutes once a week for 6 consecutive weeks. Patients were randomly assigned to TES with 0 mA (sham, n = 4); 66 % (n = 5) or 150% (n = 4) of the individual electrical phosphene threshold (EPT) current at 20 Hz. Best corrected visual acuity (BCVA, using ETDRS charts), ophthalmological examination (slit-lamp biomicroscopy, fundus examination, Goldmann-applanation tonometry) and EPT (at 3 Hz, 6 Hz, 9 Hz, 20 Hz, 40 Hz, 60 Hz and 80 Hz) were determined at baseline and at eight following visits over 17 weeks. At 5 visits (in week 1, 2, 5, 9 and 17) kinetic and static perimetry (Octopus 900®, Haag-Streit, Germany) was performed.
Results: :
All patients completed the entire follow-up. TES using DTL electrodes was well tolerated. No ocular or systemic adverse events were observed except for occasional foreign body sensation after TES (n = 3). At baseline mean ± SD values were for: BCVA 0.35 ± 0.3, EPT at 20 Hz 0.23 ± 0.14 mA, static visual field (VF): mean defect (MD) 15.7 ± 5.8 dB and mean sensitivity (MS) 6.4 ± 5.5 dB, kinetic VF area (Goldmann III4e) 7674 ± 4550 deg². Stimulation current ranged from 0.06 mA to 0.81 mA. The following changes were detected (using restricted maximum likelihood (REML) for estimation of the change under treatment; P < 0.05, Tukey-Kramer): difference (mean ± SE) for the 150%, 66% and sham-group, respectively: BCVA 0.06 ± 0.03, 0.1 ± 0.03 and 0.01 ± 0.03, P = 0.14; sensitivity for EPT at 20 Hz 0.03 ± 0.04 mA, -0.01 ± 0.03 mA and -0.004 ± 0.04 mA, P = 0.68; static VF MD 2.1 ± 1.2 dB, -0.5 ± 1.4 dB and -0.1 ± 1.2 dB, P = 0.3; VF MS -2.2 ± 1.2 dB, 0.5 ± 1.4 dB and 0.03 ± 1.2 dB, P = 0.3; static kinetic VF area -181 ± 790 deg², 304 ± 707 deg² and 135 ± 913 deg², P = 0.9.
Conclusions: :
TES in NAION patients is well tolerated and safe. Positive tendencies in the group stimulated with 66% of EPT were observed, but statistical significance was not reached. Further studies with larger sample sizes and longer duration might clarify if TES could be a therapeutic option in patients with NAION.
Clinical Trial: :
http://www.clinicaltrials.gov NCT00804102
Keywords: electrophysiology: clinical • vascular occlusion/vascular occlusive disease • growth factors/growth factor receptors