Abstract
Abstract: :
Purpose: To assess photodynamic therapy (PDT) treatment for choroidal neovascularisation (CNV) associated with age related macular degeneration (AMD) using multi–focal ERG (mfERG). Methods:Thirteen patients with AMD and 100% classic or predominantly classic CNV underwent PDT therapy. Patients were followed at 3 monthly intervals for 2 years, and treated using clinical and angiographic criteria. MfERGs and refracted logMAR visual acuities were performed. Patient were characterised into 3 three groups according to visual outcome, ‘better’, ‘stable’ and ‘worse’. Results:Mean baseline characteristics were visual acuity logMAR 0.66 and average lesion size 1.3 disc areas. The mean number of recorded mfERGs was 7 over 2 years. Rings 1 and 2 but not 3,4, and 5 of the mfERG showed a p1 density and n1 amplitude that significantly correlated with acuity (p=0.01 or less, Pearson). No correlation with lesion area to p1 density, p1 or n1 amplitude in any of the rings was found. Comparison of the mfERG results from visits 1 to 7 showed significant differences between the treated and fellow eyes from rings 1 to 3, with the most significant inter–ocular differences occurring at the fovea (ring 1). There was an improvement in p1 density and the amplitudes of p1 and n1, 2 weeks post treatment but these did not attain significance. Treatment had no effect on the latency of n1, although a shortening of p1 latency was observed. . Patients with poor visual outcomes had a greater difference in pre–treatment p1 and n1 amplitude relative to latency compared to those with improved vision following treatment (vision ‘worse’ vs. ‘stable’ amplitude 22% lower and latency 3.4% longer, ‘better’ vs. ‘stable’ amplitude 3.5% lower and latency 12.9% longer). Conclusions: The mfERG allows objective monitoring of retinal function. Amplitudes of p1 and n1 at the fovea are most affected by treatment. Patients with poor visual outcomes have a greater percentage difference between the pre–treatment amplitude and latency of p1 and n1 compared to other groups.
Keywords: electrophysiology: clinical • retina • age–related macular degeneration