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K. Matsushita, T. Fujikado, T. Morimoto, H. Kanda, Y. Tano; Phosphene evoked by transcorneal electrical stimulation in eyes with ischemic optic neuropathy . Invest. Ophthalmol. Vis. Sci. 2004;45(13):250.
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Purpose: We have reported a novel method to evaluate the phosphene evoked by transcorneal electrical stimulation (TES) using indirect pupillary reflex (IPR). In this study we report the clinical application of this method to ischemic optic neuropathy (ION). Methods: Seven eyes of 7 healthy volunteers and 7 eyes of ION whose best corrected visual acuity ranged from 20/100 to 20/20 without the recovery of vision for more than 4 months were studied. Contact lens electrode (Burian Allen type) was used for the electrical stimulation of the retina. Biphasic rectangular pulse (duration, 10 msec) was applied to the electrode via an isolator (A395, WPI). We measured the IPR evoked by TES using video–pupillography. The threshold current (TC) of subjective phosphene (SP) in the central and the peripheral visual field and that of IPR were compared with those of normal controls. The extent of SP was compared with that of visual field measured by Goldmann perimeter (GP). Results: In 7 eyes with ION, phosphene was observed in the residual visual field detected by GP. The TC of peripheral phosphene (PP) was 153±74uA, central phosphene (CP) 557±102uA, and that of IPR 430±217uA. In 7 eyes of 7 healthy volunteers, TC of PP was 71.4±17.3uA, CP 114±24.4uA, and that of IPR 146±26.7uA. The TC of CP was always higher than that of IPR in eyes of healthy volunteers, while was equal or lower than that of IPR in eyes with ION.Conclusions: In eyes with ION, the phosphene was detected in the area of preserved visual field, suggesting that the phosphene might reflect the area of residual retinal ganglion cells. The TC of the CP was higher than that of IPR in ION while lower in healthy volunteer, suggesting that ganglion cells related to pupillary reflex are less affected than those related to central vision in eyes with ION.
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