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Augusto Paranhos, Vanessa M. Gerente, Ruth R. Schor, Sergio H. Teixeira, Marcelo Felix, Dora F. Ventura, Claudio L. Lottenberg, Khallil T. Chaim, Edson Amaro; Occipital Fmri Response Is Associated With Structural Ocular Findings And Psychophysics Tests In Glaucoma Patients. Invest. Ophthalmol. Vis. Sci. 2011;52(14):3962.
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The purpose of this study was to evaluate the functional magnetic resonance imaging (fMRI) response to visual stimuli and its association with structural ocular findings and psychophysics tests in patients with glaucoma and controls.
Patients and controls performed the following exams: SAP 24-2, FDT Matrix and Stratus OCT. fMRI was performed with a 3 Tesla MRI, with 2 patterns of a reversing checkerboard visual stimuli, an expanding ring (eccentricity) and a rotating wedge (polar angle). Stimuli were presented bilaterally in 3 cycles of 60 seconds each. Visual cortex response was obtained by changes in blood flow oxygenation: BOLD (blood oxygen level dependent) effect. BOLD response was analyzed in 3 ways: "fMRI measure" was defined as the maximum peak of the BOLD response, with a delay of 3 seconds; "BOLD 90%" is the value obtained by the analysis of BOLD feat query of the FSL, and is calculated based on the predictors and the voxels considered the largest range of cumulative distribution; and "occipital response" is the average of the most significant values in the occipital pole ROI. Perimetry (SAP and FDT) results were divided into quadrants, using the average of the total deviation for each quadrant, excluding the central point that corresponds to macula. Superior and inferior average RNFL thickness were also compared to fMRI response. To compare both groups regarding anatomical and functional examinations, generalized estimating equation (GEE) models were performed.
Results: 20 individuals performed the exams, 14 with glaucoma and 6 controls. Mean age was 59.3 ± 14.8 years for control group and 61.7 ± 10.5 years for glaucoma group. Regarding polar angle stimulus, there was a statistically significant association with fMRI measure for SAP (p=<0,001) and FDT (p=0,044), and with bold90% (p=0,042) and occipital response (p=0,025) for OCT. For eccentricity stimulus, a statistically significant association was observed bold90% (p=0,015) for SAP, fMRI measure (p=0,003) and bold90% (p=0,045) for FDT and fMRI measure (p=0,029) and occipital response (p=0,001) for OCT.
Glaucoma patients have a decreased functional cortical response to visual stimuli associated with the magnitude of the visual field loss seen in SAP and FDT and RNFL thickness by OCT.
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