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.

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