Electroretinographic evaluations of retinal function before, just after and after intravitreal injections

Abstract

Intravitreal injections (IVI) have become a part of daily practice for a growing number of procedures. We evaluated the retinal function by recording intraoperative photopic electroretinograms (ERGs) before an injection (T1), just after the injection (T2), and after the aspiration of the anterior chamber fluid (T3) of 19 eyes of 19 patients (mean age 70.6 years; men = 11) who received an IVI of an anti-vascular endothelial growth factor. The mean amplitudes of the b-wave, photopic negative responses (PhNR), and oscillatory potentials (OPs) 1 and 2 at T2 were significantly smaller than that at T1, but no significant difference was observed between T3 and T1. The mean implicit times of the a-wave and OP1, 2, and 3 at T2 and the a-wave and the OP2 at T3 were significantly longer than that at T1. The mean intraocular pressure (IOP) at T2 (49.32 mm Hg) was significantly higher and the IOP at T3 (8.74 mm Hg) was significantly lower than that at T1 (21.05 mm Hg). The retinal function was reduced and the IOP elevated just after the IVI. The response of each ERG component was different suggesting a different sensitivity of each type of retinal neuron to IVI.

Effect of Paracentesis on Retinal Function Associated With Changes in Intraocular Pressure Caused by Intravitreal Injections

“…We have reported that there is a significant decrease in the b-wave amplitude during a rapid increase in the IOP and no changes when the IOP is reduced. 10 The results of this study are consistent with those findings.…”

“…We have also previously evaluated the changes in retinal function associated with a sudden increase in the IOP after an intravitreal injection in real time by intraoperative ERGs. 10 Our results showed a temporary decrease in the ERGs that occurred after the intravitreal injection, and the ERGs recovered after the IOP recovered. Therefore, some surgeons perform anterior chamber paracentesis immediately before an intravitreal injection to avoid this increase in the IOP.…”

“…First, because we recorded ERG after paracentesis, and the ERG did not show b-wave amplitude reduction; and, second we showed in a previous study that the b-wave amplitude did not show significant change after paracentesis without intravitreal injection. 10 The b-wave amplitude reduction was not accompanied by prolongation of the implicit time. The b-wave implicit time was reported to be delayed in diseases with retinal circulatory disturbance or animal models with experimentally increased IOP.…”

“…We have reported that intravitreal injection was performed without anterior chamber paracentesis, and the injection caused an increase in the IOP and caused considerable reduction in the b-wave amplitude. 10 In addition, the latencies of the a-waves and OPs were prolonged. We think that paracentesis before injection may be one of the effective choices to minimize the alteration in the electroretinographic function.…”

“…First, because we recorded ERG after paracentesis, and the ERG did not show b-wave amplitude reduction; and, second we showed in a previous study that the b-wave amplitude did not show significant change after paracentesis without intravitreal injection. 10 …”