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T. Plank, J. Frolo, A. B. Renner, S. Brandl-Rühle, H. Helbig, M. W. Greenlee; Voxel Based Morphometry in Patients With Central Visual Field Scotomas. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5470.
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© ARVO (1962-2015); The Authors (2016-present)
We used Voxel Based Morphometry to investigate structural changes in grey matter density in patients with central visual field scotomas in comparison to normal sighted subjects.
21 patients with central scotomas (13 Stargardt disease, 8 cone-rod dystrophies; age 12-66 yrs; scotoma diameter 10-40°) and 18 age-matched normal sighted controls participated in this study. Magnetic resonance imaging was performed using a Siemens 3T Allegra scanner. A high-resolution T1-weighted image (1x1x1mm) was acquired of each subject using the 3D MPRAGE sequence. The brain images were registered to the MNI template. Standard SPM5 segmentation was used to classify each voxel as grey or white matter. The images were then smoothed with a Gaussian kernel of 12 mm FWHM. For the statistical analysis the contrast "patients<controls" was defined as a two sample t-test to compare grey matter density in both groups. The factor age was added as a covariate. Additionally a regression analysis was conducted to relate grey matter density changes within the patients group to demographic and behavioral factors like age, duration of disease, visual acuity, fixation stability and scotoma size.
In comparison to the control group, patients with central scotomas show a significant loss of grey matter density around the occipital pole (BA 17,18,19; Fig. 1). Regression analysis reveals that the loss of grey matter density along the calcarine sulcus correlates to scotoma size, but not to other factors like age, duration of disease, visual acuity or fixation stability.
The analysis shows that structural changes in early visual areas of the brain occur in patients with central scotomas. Our findings are in line with those of Boucard et al. (Brain 2009:132;1898-1906), who also found reduction of grey matter density in 9 patients with age related macular degeneration around the occipital pole corresponding to the lesion projection zone. In addition, the structural changes appear to be related to the size of the central scotomas.
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