Macular degeneration (MD), the leading cause of visual impairment
in the developed world, damages the central retina, often obliterating
foveal vision and severely disrupting everyday tasks such as reading,
driving, and face recognition. In such cases, the macular damage
eliminates the normal retinal input to a large region of visual cortex,
comprising tens of square centimeters of surface area in each hemisphere,
which is normally responsive only to foveal stimuli. Using functional
magnetic resonance imaging, we asked whether this deprived cortex
simply becomes inactive in subjects with MD, or whether it takes
on new functional properties. In two adult MD subjects with extensive
bilateral central retinal lesions, we found that parts of visual
cortex (including primary visual cortex) that normally respond only
to central visual stimuli are strongly activated by peripheral stimuli.
Such activation was not observed (1) with visual stimuli presented
to the position of the former fovea and (2) in control subjects with
visual stimuli presented to corresponding parts of peripheral retina.
These results demonstrate large-scale reorganization of visual processing
in MD and will likely prove important in any effort to develop new
strategies for rehabilitation of MD subjects.