P 144Multifocal ERG in age-related macular degeneration with hard and soft drusen
B. Jurklies, M. Weismann
Introduction: To investigate and compare the functional changes in patients with age-related macular degeneration (AMD) with different types of drusen, using multifocal electroretinography (MERG).
Methods: Patients were classified as having hard (20 eyes) or soft (23 eyes) drusen by evaluating color fundus photographs or fluorescein angiography. 103 focal ERG of the central 25°x30° evoked by hexagonal stimuli were recorded using MERG (VERIS, EDI, San Francisco). Mean amplitudes and implicit times (1st order kernel) of the first through ("a-wave") and peak ("b-wave") were calculated on the basis of concentric rings (ring 1 centre; ring 6 periphery) centred around the fixation point.
Results: For both hard and soft drusen mean amplitudes of ring 1-6 were statistically significant reduced by 10-44% compared to a normal control group ("normalised" amplitudes). Soft drusen induced a decrease in normalised amplitudes more in the centre than in the periphery. Hard drusen revealed a homogenous reduction in normalised amplitudes of ring 1-5. The changes in amplitudes of ring 2-6 were pronounced more for hard drusen than for soft drusen while the amplitudes of the centre (ring 1) were affected more by soft than by hard drusen.
Implicit times (ring 1-6) were statistically significant prolonged by 9%-17% compared to a normal control group ("normalised" implicit times). This was obvious more for hard drusen than for soft drusen.
Discussion: Compared to a normal control group significant changes in amplitude and implicit time of the local retinal responses are induced by the presence of drusen. These data suggest that retinal function is affected in early stages of AMD.
Supported by Deutsche Forschungsgemeinschaft (DFG, grant JU 379/1-1)
Electrophysiology Lab, Dept Ophthalmology, University Hospital, D-45122 Essen, Germany