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Electrical optic nerve stimulation halts progression of visual field loss in glaucoma patients

      Abstract
      Introduction: Glaucoma is characterized by optic nerve degeneration and loss of retinal ganglion cells causing visual field loss. The current standard approach in glaucoma therapy is reduction of the intraocular pressure (IOP). Despite effective medications leading to IOP-lowering, glaucoma exacerbation and progressive vision loss among patients is common. Electrical stimulation of the optic nerve (ONS) facilitates axonal regeneration and survival of retinal ganglion cells. The follow-up study provides real-world evidence for long-term clinical efficacy of ONS in glaucoma.
      Methods: 70 glaucoma patients with progressive vision loss despite therapeutic IOP reduction underwent electrical ONS. Closed eyes were separately stimulated by bipolar rectangular pulses with intensities up to 1.2 mA sufficient to provoke phosphenes. Ten daily stimulation sessions within 2 weeks lasted about 80 min each. Right before ONS at baseline (PRE), visual field loss was documented by static threshold perimetry in the central 30° visual field and compared to the same assessment approximately one year afterwards (POST). Mean defect (MD) was defined as primary outcome parameter. Only perimetries with a reliability factor (RF) of max. 20% were considered.
      Results: Perimetry follow-up of 101 eyes in 70 patients fulfilled the criterion of a max. 20% RF. MD significantly decreased from PRE 14 dB (Median) to POST 13.4 dB one year after ONS (p<0.01) corresponding to an improvement of visual fields. 64 eyes in 49 patients showed constant or reduced MD as compared to baseline (Pre 13.4 dB vs. POST 11.2 dB). Considering ΔMD ≤ 0 dB as response, 63.4% of eyes in the present trial were responders.
      Conclusions: Innovative treatments that preserve visual function through mechanisms other than lowering IOP are required for glaucoma with progressive vision loss. The present long-term data document progression halt in more than 63% of affected eyes after ONS and, thus, extend existing evidence from clinical trials.
      Keywords: Vision, Glaucoma, Optic neuropathy, Retina