Multifocal Electroretinography as a Method of Functional Assessment of Retinal Laser Injury in Experimental Studies

Purpose: to investigate local functional changes in the rabbit retina by multifocal electroretinography under pulsed laser radiation.Materials and methods. Transpupillary applications by single laser pulses (Nd:YAG laser, 532 nm, 50 ms) with the diameter of the laser beam spot on the retina surface of 132 µm (15 eyes) and 200 µm (15 eyes) were performed on 30 eyes of 15 rabbits. In each eye were applied 6 applications of different laser pulse power (15, 30, 50, 100, 150 and 200 mW). The diameter of the injury zone was assessed ophthalmoscopically and histologically. Multifocal electroretinography was performed before and 30 minutes after exposure using a module for multifocal electroretinography Neuro-ERG (Neurosoft, Russia), topographically comparing a pattern of 61 hexagons with an ophthalmoscopic fundus picture. The amplitude (µV) of the P1 peak and the implicit times (ms) of the P1 and N1 peaks were estimated in the first-order response in the hexagons corresponding to the laser damage zones.Results. When using a laser spot on the retina of 132 microns and 200 microns, the threshold level of laser radiation power for the development of significant local changes in the bioelectric activity of the retina was 50 and 30 mW, respectively (p < 0.05). The minimal diameter of the laser damage at which significant functional changes are recorded by multifocal electroretinography with a pattern stimulator consisting of 61 hexagons was 127.2 ± 6.4 µm (spot 132 µm, energy 50 mW), while a significant relationship was found between changes in the peak amplitude P1 and ophthalmoscopic and histological dimensions of the damage zone (r = 0.73 and r = 0.71, respectively, p < 0.01).Conclusion. The use of multifocal electroretinography can be used to quantify functional changes in local laser damage to the retina in experimental studies on rabbits.

The Many Faces of Acute Idiopathic Blind Spot Enlargement

This is a literature review and retrospective case series of acute idiopathic blind spot enlargement of 2 Caucasian females and 1 Hispanic male. Hallmark findings include unilateral photopsia, an enlarged blind spot, loss of the ellipsoid and interdigitation zones on OCT, and an abnormal multifocal electroretinography. This condition is an outer retinal disease that shares common traits with the AZOOR complex, which can confound the diagnosis. Autofluorescent imaging may aid in differentiating the conditions. Disseminating more case reports detailing different presentations of this rare outer retinal disorder help advance the clinical understanding of these conditions.

ISCEV standard for clinical multifocal electroretinography (mfERG) (2021 update)

The multifocal electroretinogram (mfERG) is an electrophysiological test that allows the function of multiple discrete areas of the retina to be tested simultaneously. This document, from the International Society for Clinical Electrophysiology of Vision (ISCEV), presents an updated and revised ISCEV standard for clinical mfERG and defines minimum protocols for basic clinical mfERG recording and reporting so that responses can be recognized and compared from different laboratories worldwide. The major changes compared with the previous mfERG standard relate to the minimum length of m-sequences used for recording, reporting of results and a change in document format, to be more consistent with other ISCEV standards.