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T. Fukui, T. Morimoto, K. Matsushita, T. Fujikado, Y. Tano; Estimation of residual ganglion cells by phosphene evoked by transcorneal electrical stimulation in patients with retinal degeneration. . Invest. Ophthalmol. Vis. Sci. 2004;45(13):4335.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: The artificial retina requires the activation of residual retinal ganglion cells (RGCs). Therefore, we have to select candidates whose retinal ganglion cells are preserved. In this study we examined residual function of RGCs in patients with retinal degenerations using phosphene evoked by transcorneal electrical stimulation (TES). Methods: Nine eyes of nine patients with retinal degeneration in which visual acuity was worse than 20/500 were examined. According to the residual visual field, patients were classified into two groups. One is with preserved central visual field (central type) and the other with residual peripheral visual field (peripheral type). TES was applied using Burian–Allen contact–lens electrode with biphasic pulse train. The threshold current (TC) of subjective phosphene (SP) and that of indirect pupillary reflex (IPR) were compared with those of normal controls. The extent of SP was compared with that of visual field measured by Goldmann perimeter. Results: In the central type, the TC to induce SP in both central and peripheral visual field and that of IPR were higher than those of normal controls. In the peripheral type, the TC of SP from the peripheral visual field was almost the same as that of normal controls, but the TC of SP from the central visual field and that of IPL were higher than those of normal controls. The area of SP with low stimulus current was consistent with the residual visual field measured by Goldmann perimeter but the area was enlarged with the increase of stimulus current. Conclusions: With the subjective phosphene and the indirect pupillary reflex evoked by TES, we can estimate the residual function of RGCs in nine patients with retinal degenerations. This method may be useful to select candidates for artificial retina.
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