Focal macular electroretinograms after photodynamic therapy combined with intravitreal bevacizumab

Abstract

Background: Retinal function is transiently depressed after photodynamic therapy (PDT) alone. One of the reasons for this functional impairment is a reduction of choroidal circulation caused by the PDT. The purpose of this study was to determine whether PDT combined with intravitreal bevacizumab (PDT+IVB) can reduce or prevent the transient impaired macular function. In addition, we examined whether a significant correlation existed between the changes in the focal macular electroretinograms (FMERGs), optical coherence tomography (OCT)-determined morphology, and changes in choroidal circulation.

Methods: Thirty-eight eyes that were treated by full fluence PDT+IVB were studied. FMERGs, OCT, and indocyanine green angiography (ICGA) were performed before and after the PDT. The intensity of the diffuse fluorescence within the PDT site was measured by densitometry (I/N ratio).

Results: The macula was significantly thinner 1 week after PDT+IVB (P < 0.01). The mean a- and b-wave amplitudes of the FMERGs were not significantly decreased 1 week after PDT+IVB. The mean b-wave amplitudes 3 months after PDT+IVB were significantly increased (P < 0.01). The I/N ratio of ICGA 3 months after PDT+IVB was 0.88 ± 0.1. The correlation between the FMERGs and I/N ratio was not significant.

Conclusion: The use of IVB with PDT mitigates the reduction of the FMERGs and reduces the macular thickness soon after PDT, regardless of the degree of impairment of choroidal circulation caused by PDT. Finally, the macular retinal function 3 months after PDT+IVB were better than that before the treatment.