Which Multifocal ERG Parameters Best Predict the Need for and Timing of Photodynamic Retreatment

Abstract

Abstract: : Purpose:Photodynamic therapy (PDT) using verteporfin (Visudyne) has been shown to be an efficacious treatment of subfoveal choroidal neovascularization due to age-related macular degeneration. The majority of patients receive PDT retreatment on average every 3-5 months; however, there is increasing interest in earlier PDT retreatment of lesions. The purpose of this investigation is to determine which parameters of the mERG have the greatest clinical utility in determination of both the timing and need for retreatment. Methods:16 eyes of 15 patients (aged 50 - 92 years) receiving PDT were examined over 36 treatments. For each patient multifocal ERGs were recorded with dilated pupils and DTL electrodes. A VERIS Science system 4.3 stimulated 61 hexagonal regions in the central 45 degrees using a fundus camera/stimulator system to monitor fixation. Mean response density and implicit time of the first order kernel were evaluated for the P1 component in the central 10 degrees and paracentral 10-45 degree regions. Patients were examined before PDT and at 1 and 3 months following. Results:One month following PDT, mERGs showed significantly improved P1 latency (P<0.02) but no significant change in central response density. By 3 months post-PDT central P1 latency significantly increased (p<0.04) towards pretreatment levels; with no significant change in central response density. Conclusion:Timing and not amplitude of the P1 component measured in the central 10 degrees appears to better predict need for PDT retreatment.

Keywords: 308 age-related macular degeneration • 395 electroretinography: clinical • 516 photodynamic therapy