Transorbital electrical stimulation as a vision restoration tool in patients with significant optic atrophy due to primary open-angle glaucoma. Acronym: VIROA (Vision Restoration in Optic Atrophy)

• Applicants: Professorin Dr. Andrea Antal; Professor Dr. Michael P. Schittkowski
• Subject Area: Ophthalmology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 465441240

Glaucoma is one of the most common causes of blindness and affects more than 70 million people worldwide. It is characterized by the loss of retinal ganglion cells associated with a progressive optic neuropathy resulting in an impairment of visual function, e.g. visual field loss (Crabb 2016). To date, glaucoma can only be treated by lowering intraocular pressure to slow down the progressive course of the disease. Indeed, the underlying mechanisms are not targeted by the current treatment strategies, and vision loss, once present, cannot be restored. Therefore new treatment options are required to improve vision as the nerve fibre loss, once it is manifest, is not reversible, neither by medication nor by surgical approach. Strong evidence from animal studies supports the hypothesis that electrical optic nerve stimulation could restore vision in affected patients. Transcorneal ES was successfully applied in retinitis pigmentosa (Schatz et al. 2017) and in patients with retinal arterial occlusion (Naycheva et al. 2013). In several small trials and one multicenter study, rtACS was performed daily in an attempt to re-activate residual vision in optic neuropathy using frequencies ranging from theta to high beta via electrodes placed near the eye. The treatment increased light detection performance and reduced the patient-reported, vision-related daily living impairments that correlated moderately with visual field gains (Fedorov et al. 2011, Gall et al. 2013b, Gall et al. 2011, Gall et al. 2013c, Sabel et al. 2011a, Sabel et al. 2011b, Schmidt et al. 2013). In a multicenter trial rtACS or sham stimulation was applied in two series of five consecutive days separated by a weekend break. The participants included patients with optic nerve damage (Gall et al. 2016). The rtACS group had a significantly greater mean improvement of visual field measurements compared to the sham stimulation group for up to two months post-treatment. However, the level of evidence of this method is still fairly poor, and further trials are necessary. In the opinion of German ophthalmological societies (i.e.DOG and BVA), the applied methods were not satisfactory (e.g. non-established perimetry methods, lack of the measurements of eye movements, inhomogeneous patient populations, and incorrectly defined trial endpoints (http://www.dog.org). This proposed multi-center double-blind sham-controlled study aims to clarify the contradictory data in this field and uses established and well-defined visual-field parameters. The novel aspects of this trial are the individual current flow modeling based on the visual impairment and the application of stimulation protocol with predefined electrode montage and fixation of a target during the experiment. Furthermore, it will study an extremely well-defined and homogenous patient population.

• DFG Programme: Clinical Trials
• Co-Investigator: Professor Dr.-Ing. Jens Haueisen