Does Photodynamic Retreatment Affect the Multifocal ERG?

Abstract

Abstract: : Purpose: Photodynamic therapy (PDT) using verteporfin (Visudyne) has been shown to be an efficacious treatment of subfoveal choroidal neovascularization (CNV) due to age-related macular degeneration. The majority of patients receive PDT retreatment on average every 3-5 months. Previously, we have described the effect of serial PDT retreatment on multifocal electroretinography (mERG) in areas overlying the CNV (ARVO 2002). The effect of PDT on presumably healthy retina lying within the treatment zone has not been investigated with mERG. The purpose of this investigation is to assess the effect of PDT retreatment in those areas outside of the area of CNV, but still within the zone of PDT treatment. Methods: 9 eyes of 8 patients (aged 54 - 92 years) receiving PDT were examined over two treatments. Multifocal ERGs were recorded from 61 hexagonal regions in the central 45 degrees. The mERG trace arrays were superimposed over pretreatment fluorescein angiograms and mERG traces lying outside of the CNV but within the treatment zone were identified. Mean response density and implicit time of the first order kernel were evaluated for the P1 component in those areas at 1^st and 2^nd PDT treatment. Results: For those areas lying outside of the CNV but within the treatment zone there were no significant differences in P1 timing (p>0.20) or amplitude (p>0.25) noted at the time of second PDT treatment. Conclusions: PDT treatment does not appear to alter electroretinal function of presumably healthy retina lying within the treatment zone.

Keywords: age-related macular degeneration • electroretinography: clinical • photodynamic therapy