Delayed trans-scleral electrical stimulation preserved the survival of retinal ganglion cells after ischemia-reperfusion injury in mice model

Abstract

Purpose: Trans-corneal electrical stimulation (TcES) has shown neuroprotective effects on retina under stress. Compares to TcES, the pads of trans-scleral electrical stimulation (TsES) were placed on the sclera without touching cornea, will not damage the cornea even when applied repeatedly. In this study, we studied the effect of TsES on retinal ganglion cells (RGCs) with 24 hours delayed application in a mouse model of retinal ischemia-reperfusion injury. Methods: Adult C57BL/6J mice were divided into 4 groups: A) normal; B) sham; C) pad; D) TsES group. Retinal ischemia was induced by cannulation of the anterior chamber with a 33G needle connected to a sterile fortified balanced salt solution (BSS Plus) bag. The water level of BSS bag was set at 170 cmH2O above the eye level to create a consistent hydrostatic pressure for 60 minutes. And intraocular pressure (IOP) was monitored during the ischemia procedure. At 24 hours after the reperfusion, a pair of tailor-made gold pads were placed at the medial and lateral canthus of the mouse eye. In the TsES group, the parameters are frequency at 20 Hz, power at 100 microA for 30 mins, while no ES was applied in the pad group. Retina samples were collected at 7 days after the ischemic injury. Morphological changes of retinal neurons were analyzed in cross sections and flat mounted retinas. Results: Under general anesthesia, IOP measured by Tonolab was 84±4.6 mmHg during ischemic insult.60-minute acute retinal ischemia followed by reperfusion for 7 days could induce nearly 60% of RGC loss. The survival rate of RGC in the TsES group was about 10% more than that in the pad control group. Conclusions: Twenty-four hours delayed TsES has neuroprotective effect on ischemia-reperfusion induced RGC loss. This treatment window is very important to patients with such ischemia insult or acute glaucoma. Layman Abstract (optional): Provide a 50-200 word description of your work that non-scientists can understand. Describe the big picture and the implications of your findings, not the study itself and the associated details.