Electrophysiologic findings after intravitreal bevacizumab (Avastin) treatment

Abstract

Purpose: To evaluate the short-term electrophysiologic effects of intravitreal bevacizumab in the treatment of exudative age-related macular degeneration (AMD).

Methods: Nine subjects with AMD who received treatment with intravitreal bevacizumab for exudative AMD underwent pretreatment testing with multifocal electroretinography (mf-ERG) or Ganzfeld electroretinography (G-ERG). All five G-ERG subjects underwent repeated testing at 1 week after intravitreal bevacizumab. All four mf-ERG subjects and four of the five G-ERG subjects underwent repeated testing with the same pretreatment protocol at 1 month after treatment. One G-ERG subject also received a second intravitreal injection of bevacizumab at 6 weeks after initial treatment and underwent repeated testing at 1 month after the second dose (3 months after initial treatment).

Results: All four subjects undergoing mf-ERG had improvement of the macular response at 1 month of after treatment. The average improvement in response density of the central 15 degrees of macular response was 35% (range, 11-65%). Subjects undergoing G-ERG testing had no significant changes in electrophysiologic response, although some variation in amplitude and implicit time was noted at different testing times. Optical coherence tomography central subfield thickness decreased from 298 microm at baseline to 274 microm at 1 month after treatment. Visual acuity improved in a majority of subjects.

Conclusion: In this study, the intravitreal use of bevacizumab resulted in improvement of mf-ERG macular function responses and relatively stable G-ERG responses. The macular electrophysiologic response suggests that macular function improves with treatment. G-ERG suggests that there is no significant measurable photoreceptor toxicity with the use of intravitreal bevacizumab over the short term.