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Takashi Fujikado, Takeshi Morimoto, Hiroyuki Kanda, Kohji Nishida; Evaluation of inner-retina using OCT and Transcorneal Electrical Stimulation (TES) in Candidates of Retinal Prosthesis by Suprachoroidal-transretinal Stimulation (STS). Invest. Ophthalmol. Vis. Sci. 2012;53(14):5535.
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© ARVO (1962-2015); The Authors (2016-present)
Patient selection is crucially important for the success of retinal prosthesis.The acute and sub-acute clinical trials by retinal prosthesis using suprachoroidal-transretinal stimulation (STS) showed that the number of effective electrode to elicit phophene by STS correlated with the threshold current examined by pre-surgical transcorneal electrical stimulation (TES). In this study, we investigated the relationship between the retinal thickness by optical coherence tomography (OCT) and the threshold current to evoke phosphene by TES in patients with advanced retinitis pigmentosa (RP) who were candidates of retinal prosthesis
Eighteen eyes of 10 patients with RP (average age, 65.7 years) were examined. The best-corrected visual acuity (BCVA) ranged from 0 to HM (median, LP). Retinal thickness (RT) was measured by macular cube scan (512x128) of OCT (Cirrus). The threshold current to evoke phosphene in the central visual field (central phophene) by TES (10ms/phase,20Hz,20 pulses) was evaluated.
The central phophene was elicited in 8 eyes but was not elicited with current less than 2 mA in 10 eyes. The average RT at parafoveal area (Φ=3mm) was significantly thicker in a group with central phosphen than that without central phophene (238±65um vs 144±78um, P=0.015). All four eyes with RT thicker than 250um perceived central phophene. No correlation was observed between BCVA and parafoveal RT.
RP patients with parafoveal RT thicker than 250 um by OCT can be candidates but other patients should be examined by TES before going to the clinical trial of STS retinal prosthesis.
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