Purchase this article with an account.
J.S. Sunness, T. Liu, C.A. Applegate, S. Yantis; Retinotopic Mapping of Visual Cortex in Patients With Central Scotomas From Macular Disease . Invest. Ophthalmol. Vis. Sci. 2003;44(13):5003.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: Our goal is to determine whether remapping of the primary visual cortex occurs as a result of loss of stimulation from an area of macular atrophy, and whether this remapping will help us to understand the variability among patients in their ability to use an eccentric preferred locus of fixation and optimize the use of their remaining vision. We present early data on retinotopic mapping of the visual cortex, using functional MRI. Methods: Subjects are patients with well-defined central scotomas associated with atrophic macular disorders. SLO analysis of fixation location and stability, and size and location of dense scotoma is performed. fMRI mapping of the visual cortex is performed by measuring changes in blood oxygenation due to local neural activity. The stimulus is an annulus, filled with black and white checks reversing at 8 Hz, that begins in the center and expands outward to 7 degrees eccentricity. The timing of the responses in the visual cortex reflects the (retinal) location of the annulus responsible for stimulating that cortical area. Results:A 60 year old woman with bilateral geographic atrophy, with visual acuity of 20/50-2 in the better-seeing os was tested. SLO imaging shows the presence of a large area of GA ou. The fixation cross is placed, with excellent stability, just at the superior edge of the atrophy nearest the fovea. There was a dense scotoma corresponding to the area of GA. fMRI revealed a loss of activity in the ventral cortex, corresponding to the inferior retina, while the representation in the dorsal cortex, corresponding to the superior retina, was relatively intact. Conclusions: Retinotopic mapping of the visual cortex in GA patients is possible. Testing patients with discrete scotomas will provide a 'metric' for the mapping that can be used to determine if and when remapping occurs.
This PDF is available to Subscribers Only