Abstract
Abstract: :
Purpose: The intra–ocular electroretinogram (ioERG) is a focal, targeted ERG recorded during pars plana vitrectomy. The ioERG provides unique occasion for focal electrophysiological recording of posterior and peripheral fundus tissues to assess electroretinal function of detached and reattached retina, macular holes, ischemic and poorly perfused retina. These intraocular recordings are robust, replicable and can be obtained within seconds during the course of par plana vitrectomy. Methods: ioERGs were recorded from 40 patients undergoing par plana vitrectomy for various conditions including rhegmatogenous retinal detachment, epiretinal membrane removal and macular hole repair. Standard 20 gauge three–port surgical procedure was used. A custom–made light emitting diode stimulator was utilized to deliver photic stimulation through the surgical endoilluminator (Alcon Accurus) at a 10 Hz. stimulation frequency. Local electroretinal signals were recorded using sterile microconductive fiber electrodes (DTL–Plus) secured to the port. The ioERGs were amplified and digitally filtered (9–11 Hz bandpass) with an Espion (Diagnosys LLC) system. Twenty sweeps of 250 millisecond duration were sampled within 5 seconds. Focal targeted regions were selected for recording during pars plana vitrectomy. Results: The ioERG from the normal macula ranged from 3–6 Uv in trough to peak amplitude. No evidence of significant light scatter was confirmed with stimulation at the optic nerve head. Withdrawal of the endostimulator away from the retinal surface increased response amplitude and peak implicit time. The ioERG was able to reliably discern functional improvement in retinal regions following reattachment and were extinguished in areas of re–attached chronic retinal detachment. Conclusions: Intraocular electroretinography provides unique opportunities for focal, targeted electroretinal evaluation of posterior and peripheral fundus tissues with potential for novel clinical and research utilities.
Keywords: vitreoretinal surgery • electroretinography: clinical • retinal detachment