Abstract
Purpose: :
It is known that the local response of multifocal electroretinograms often become smaller soon after photodynamic therapy (PDT). The purpose of this study was to determine whether this amplitude reduction is correlated with the changes in foveal thickness or indocyanine green angiographic (ICGA) findings.
Methods: :
Nineteen eyes (12 with age–related macular degeneration, and 7 with polypoidal choroidal vasculopathy) which were successfully treated by PDT, were studied. Focal macular electroretinograms (FMERGs) were elicited by a 15 degrees stimulus spot centered on the fovea, and monitored by an infrared fundus camera. The foveal thickness was measured by optical coherence tomography (OCT) before, and 1 week, 1 month, and 3 months after PDT. ICGA was preformed before and 3 months after PDT. The ICGA findings were classified into two groups; a clear hypofluorescence coinciding with the site of the PDT (Group A) and indistinct hypofluorescence at the site of the PDT (Group B).
Results: :
The mean b–wave amplitude of the FMERG was significantly reduced 1 week, 1, and 3 months after PDT (P < 0.05; Wilcoxon signed rank test) compared to those before PDT. There was no correlation between the changes in the amplitude of FMERG and the changes in the foveal thickness. The mean ratio of the FMERG b–wave 1 week after PDT to that before PDT was 0.585 in Group A (12 eyes), and 0.802 in group B (7 eyes). This difference was statistically significant (P=0.047; Mann–Whitney U test).
Conclusions: :
These results suggested that the reduction in the amplitude of the FMERG at the early stages after PDT may be related to the reduction in choroidal circulation caused by PDT.
Keywords: age-related macular degeneration • photodynamic therapy • electroretinography: clinical