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Lubka Naycheva, Mariya Gosheva, Johanna Pach, Andreas Schatz, Eberhart Zrenner, Florian Gekeler, Okuvision; Identifying High and Low Responders to Transcorneal Electrical Stimulation Treatment for Patients with Retinitis Pigmentosa. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3804.
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© ARVO (1962-2015); The Authors (2016-present)
To assess efficacy of treatment and explore high responders to transcorneal electrical stimulation (TES) in patients with retinitis pigmentosa (RP).
63 eyes of 63 patients with RP (33 m, 30 f, age range 19-74) were treated with TES (5 ms + 5 ms biphasic pulses at 20 Hz). TES was applied for 30 minutes weekly for 52 consecutive weeks with an OkuEl®-transcorneal electrode and an OkuStim®-Device (Okuvision GmbH, Germany). Patients were randomly assigned to three study aims: TES with 0 mA (sham, n = 22); 150% (n = 21) or 200% (n = 20) of the individual electrical phosphene threshold (EPT) current at 20 Hz. Best corrected visual acuity, ophthalmological examination (slit-lamp biomicroscopy, fundus examination, Goldmann-applanation tonometry) and EPT were determined at baseline and at 8 following visits (at week 10, 16, 22, 28, 34, 40, 46 and 52). At 5 visits (at week 1, 16, 28, 40 and 52) kinetic visual field (VF) (Octopus 900®, Haag-Streit, Germany), optical coherence tomography (Spectralis®-OCT, Heidelberg Engineering GmbH, Germany), full-field electroretinography and dark adaptation were performed. To identify high responders, patients were divided into 3 groups according to the baseline size of the VF area using stimulus Goldmann III4e: small (234-2447 deg²), medium (2628-6792 deg²) and large (6806-14587 deg²) VF area.
52 patients (27 m, 25 f; TES = sham: n = 20, TES = 150%: n = 15 and TES = 200%: n = 17) completed the entire study. Using restricted maximum likelihood (REML) for estimation of changes under treatment (P < 0.05, Tukey-Kramer), in the group with small VF area (n = 18) a positive tendency for VF area enlargement (P = 0.14) was detected, but statistical significance was not reached. In the groups with medium (n = 18) and large (n = 18) VF area no such tendency was observed (respectively P = 0.62 and P = 0.21).
A positive tendency for an enlargement of VF area was observed in the group with the smallest VF area. However, results were not statistically significant. Particularly, patients with a smaller VF area (below ~27 deg) seem to benefit more from TES and could be classified as high responders.
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