Abstract
Purpose: :
To assess the safety and efficacy of transcorneal electrical stimulation (TES) in patients suffering from retinal artery occlusion (RAO).
Methods: :
13 patients with RAO (12 patients with central and 1 patient with branch RAO, age range 25-84, median 74 years) were enrolled in the study. RAO was diagnosed 1 week to 17 months before study participation. Patients were treated with TES (5 + 5 ms biphasic pulses at 20 Hz; applied with DTL electrodes) for 30 minutes once a week for 6 consecutive weeks. Patients were randomly assigned to TES with 0 mA (sham, n = 3); 66 % (n = 5) or 150% (n = 5) of the individual electrical phosphene threshold (EPT) current at 20 Hz. Visual acuity (VA), ophthalmological examination and EPT (at 3, 6, 9, 20, 40, 60 and 80 Hz) were determined at baseline and at eight following visits over 17 weeks. At 4 visits (in week 1, 5, 9 and 17) kinetic and static visual field (VF) as well as Ganzfeld- and multifocal - electroretinography (Ganzfeld-ERG and mfERG) were 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 foreign body sensation after TES (n = 2). At baseline mean ± SD values were for: VA Snellen 1.5 ± 0.6 logMAR, EPT at 20 Hz 0.97 ± 1.06 mA, static VF: mean defect (MD) 15.7 ± 5.1 dB and mean sensitivity (MS) 4.96 ± 3.8 dB, kinetic VF area (Goldmann III4e) 10433.5 ± 3123.3 deg². Stimulation current was 0.1 - 1.75 mA. The following changes were detected (using restricted maximum likelihood (REML) for estimation of the change under treatment; P < 0.05, Tukey-Kramer): mean ± SE for the 150%, 66% and sham-group, respectively: VA 0.26 ± 0.09 logMAR, 0.21 ± 0.09 logMAR and 0.26 ± 0.11 logMAR, P = 0.89; sensitivity for EPT at 20 Hz 0.3 ± 0.2 mA, 0.2 ± 0.2 mA and 0.1 ± 0.2 mA, P = 0.85; static VF MS 0.18 ± 1.4 dB, 1.8 ± 0.8 dB and 1.6 ± 1.1 dB, P = 0.6; static VF MD 0.14 ± 1.8 dB, -1.4 ± 0.8 dB and -1.6 ± 1.1 dB, P = 0.7; a-wave-slope of single flash (SF) 10 cd.s/m² 1.04 ± 0.05 µV, 0.87 ± 0.05 µV, 0.9 ± 0.06 µV, P = 0.052; photopic a-wave-amplitude of SF 3 cd.s/m² 1.1 ± 1.1 µV, 4.1 ± 1.1 µV, 1.1 ± 1.4 µV, P = 0.12; mfERG center-ring-amplitude 3.1 ± 0.8 µV, 1.1 ± 0.8 µV, 0.9 ± 1.0 µV, P = 0.19.
Conclusions: :
TES in RAO patients is well tolerated and safe. A positive tendency was observed, but statistical significance was not reached, probably due to the small sample size. Further studies with larger sample sizes and longer duration might be required to explore a possible positive effect.
Clinical Trial: :
http://www.clinicaltrials.gov NCT00804102
Keywords: electrophysiology: clinical • vascular occlusion/vascular occlusive disease • growth factors/growth factor receptors