The Effect of Transcorneal Stimulation in Cases of Central Retinal Artery Occlusion Using a New Waveform

Patients with acute central retinal artery occlusion (CRAO) generally present with a history of painless visual loss that occurred over several seconds. In some instances amaurosis fugax is also present. At the time of initial examination, visual acuity in 90% of patients with CRAO can vary from counting fingers to light perception. Acute CRAO is considered an emergency situation, and therapy must be started as soon as possible. There are different reports where different treatments were proved for the acute phase for example: ocular massage, anterior chamber paracentesis, intravenous mannitol, acetazolamide, hyperbaric oxygenation, microcatheter urokinase infusion, and carbogen 1,2,3. Electrophysiological occlusion of the ophthalmic artery, central retinal artery occlusion, or central retinal vein has a profound impact on the ERG. ERG can provide an objective assessment of severity if occlusion occurs, the b wave is eliminated and a reduction in the "a" wave can be observed.

In addition, a traumatic optic neuropathy, together with retinal ganglion cell death, can induce a loss of vision which progresses rapidly within several hours l. It is known that the visual prognosis following treatment of acute central retinal artery occlusion is not as good as we would like 2; the patient must go to any emergency department to be treated immediately3, in order to preserve maximal visual function. It has been prove that the retinal function recovers after an ischemic event lasting up to 97 minutes, 4 and irreparable damage may occur after 105 minutes. This is why this study intervene during the chronic phase between 4 hrs and 14 days; where demonstrable clinical improvements in the magnitude of retinal damage where seen5, 6, 7 However recently research reports have shown that, electrical stimulation can rescue injured retinal ganglion cells from death cells and can preserve visual function after an optic nerve crush. 8 There is no ideal treatment in the chronic phase of the CRAO. That is the reason why most recent papers suggest different treatment approaches in the chronic phase of this pathology. One of these treatments that were described is the application of electrical stimulation on the patient's cornea who present with CRAO. It has been reported in the literature that transcorneal, retinal 9,10 or cerebral visual cortex 11 electrical stimulation (ES) results in evoked visual sensations (phosphenes),6,9,10,12 however, this intervention requires surgical electrode implantation.