Schröder B., Frei J., Flammer J., Prünte C.

University Eye Clinic Basel, Switzerland

Purpose: Photodynamic therapy (PDT) using Verteporfin is a new promising therapy for predominantly classic CNV in patients with agerelated macular degeneration. However, the effects of PDT on retinal function and RPE are still largely unknown. The aim of this study was to investigate whether multifocal Electroretinography (m-ERG) can provide relevant information about retinal function after PDT.
Method: In 15 patients with predominantly classic, subfoveal CNV due to age-related macular degeneration m-ERG was performed before and 1 and 12 weeks after treatment using a first order kernel. The m-ERG was evaluated by rings, calculating amplitudes and latencies for the a- and bwave. Statistical evaluation was done with a t-test for dependent samples.
Results: One week after treatment a- and b-wave amplitudes were significantly reduced by 20-60% in the treated area, although mean visual acuity remained stable (20/70). No significant changes were found in nontreated areas. 12 weeks after treatment the amplitudes showed complete recovery and mean visual acuity improved to 20/50 without reaching statistical significance.
Conclusions: These findings suggest that retinal function is temporarily impaired after PDT in the treated area with a tendency to recover. M-ERG seems to be a more reliable and objective method for retinal function follow-up after PDT than visual acuity only. Visual acuity failed to mirror the initial decrease of m-ERG amplitudes, in our opinion, due to the improvement of metamorphopsia following treatment. m-ERG examination can be relevant for determining optimal PDT retreatment strategies.

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