Article
Multifocal ERG in age-related macular degeneration with choroideal neovascularization prior to and after photodynamic therapy
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Published: | September 22, 2004 |
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Outline
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Objective
To objectively investigate and compare focal abnormalities of retinal function in patients with choroideal neovascularization (CNV) due to age-related macular degeneration (AMD) prior to and after photodynamic therapy (PDT) using multifocal electroretinography (Mf ERG).
Methods
PDT was performed in 61 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 disease. 103 focal ERG's of the central 25° x 30° evoked by hexagonal stimuli were recorded using mfERG (VERIS-system, EDI, San Francisco). The stimulus was presented with a maximal luminance of 300cds/qm. The response components were extracted for each stimulated retinal location. Mean amplitudes and implicit times (1st oder 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 (ring1-6) of both groups were statistically significant reduced and implicit time were prolonged compared to a normal control group. After PDT the normalized P1 amplitudes (expressed as an percentage of the values prior to PDT) of group I revealed only minor while those of group II decreased. In addition mean implicit times of group I were decreased (ring 1-2) and stable (ring 3-6), while those for group II were prolonged (ring1-6) following PDT.
Conclusions
Compared to a normal control group significant changes in amplitude and implicit time were recorded. In addition, retinal function following PDT detected by MfERG was more effected for occult CNV than for classic CNV. These results corroborate with clinical findings that the functional outcome following PDT may be mor favourablefor classic CNV than for oocult CNV.