Abstract
Abstract: :
Purpose: To objectively investigate and compare focal abnormalities of retinal function in patients with choroidal neovascularization (CNV) due to age–related macular degeneration (AMD) prior to and after photodynamic therapy (PDT) using multifocal electroretinography (MfERG). Methods: PDT was performed in 62 eyes with subfoveal CNV due to AMD. Based on findings in fluorescein angiography 43 eyes were classified as classic and predominantly classic CNV (group I) and 18 eyes were classified as occult CNV with a progression of the disease. 103 focal ERGs of the central 25°x30° evoked by hexagonal stimuli were recorded using MfERG (VERIS–system, EDI, San Francisco). The stimulus was presented with a maximal luminance of 300 cds/sqm. The response components were extracted for each stimulated retinal location. Mean amplitudes and implicit times (1st order kernel) of ring 1 (center) to ring 6 (periphery) with different eccentricity were evaluated and compared to a normal control group. Normalized amplitudes of the first peak (P1 component) were calculated and compared to each other. Results: Prior to and after PDT mean amplitudes (ring 1–6) of both groups were statistically significant reduced and implicit times were prolonged compared to a normal control group. After PDT the normalized P1 amplitudes (expressed as an percentage of the values prior PDT )of group I revealed only minor changes between +2% and –10% while those of group II were decreased by 20% to 50%. In addition, mean implicit times of group I were slightly decreased (ring 1,2) and stable (ring 3–6), while those for group II were prolonged (ring 1–6) following PDT, following. Conclusions: Compared to a normal control group significant changes in amplitude and implicit time (P1) were recorded. In addition, retinal function following PDT detected by MFERG was more affected for occult CNV than for classic CNV. These results corroborate with clinical findings that the functional outcome following PDT may be more favourable for classic CNV than for occult CNV. Supported by Deutsche Forschungsgemeinschaft (DFG, grant JU 379/2–1) CR: None
Keywords: electroretinography: clinical • photodynamic therapy • choroid: neovascularization