Age-related maculopathy (ARM) has become the major cause of blindness
in the Western World. Currently its pathogenesis and primary site of
functional damage is not fully understood but ischemia is believed to play
a major role. Early detection and precise monitoring of progression of ARM
are main goals of current research due to lack of sufficient treatment
options, especially in the dry, atrophic form of this disease. We applied
the multifocal electroretinogram (mfERG) that can detect any local
functional deficit objectively in the central retina. We recorded two
paradigms in early ARM patients, the fast flicker and the slow flash
paradigm which both represent fast adaptation processes of the proximal
retina but under differing photopic conditions and stimulation rates. By
subtracting the waveform responses we extracted a late component in the
difference waveform that was significantly reduced in the early ARM group
compared to a healthy control group (p ≤ 0.05). We propose
that this multifocal nonlinear analysis permits the detection of
adaptative deficits and provides topographic mapping of retinal
dysfunction in early ARM. The difference waveform component we extracted
with this novel approach might indicate early functional loss in ARM
caused by ischemia in postreceptoral layers such as bipolar cells and
inner plexiform regions.