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Evaluation of Glaucomatous Damage via Functional Magnetic Resonance Imaging, and Correlations Thereof with Anatomical and Psychophysical Ocular Findings.

Gerente VM, Schor RR, Chaim KT, Felix Mde M, Ventura DF, Teixeira SH, Lottenberg CL, Amaro E, Paranhos A - PLoS ONE (2015)

Bottom Line: Binocular VF in each quadrant was determined using an integrated method.The response of the visual cortex to binocular stimulation was associated with binocular VF sensitivity.RNFL thickness was associated with the BOLD response of the calcarine and occipital pole ROIs.

View Article: PubMed Central - PubMed

Affiliation: Ophthalmology Department, Federal University of São Paulo, São Paulo, Brazil; Hospital Israelita Albert Einstein, São Paulo, Brazil.

ABSTRACT

Purpose: To evaluate the functional magnetic resonance imaging (fMRI) response to binocular visual stimulation and the association thereof with structural ocular findings and psychophysical test results in patients with glaucoma, and controls.

Methods: Cross-sectional study. Participants underwent a complete ophthalmic examination, including Humphrey 24-2 visual field (VF) testing and optical coherence tomography. Binocular VF in each quadrant was determined using an integrated method. Patients with glaucoma were assigned to three subgroups: initial, asymmetrical and severe glaucoma. Regions of interest (ROIs) were determined anatomically. fMRI (3 T) was performed using a bilaterally presented polar angle stimulus, and the accompanying changes in blood oxygen level-dependent (BOLD) signals were obtained from the occipital poles and calcarine ROIs. We used generalized estimation equation models to compare anatomical and functional data between the groups.

Results: A total of 25 subjects were enrolled, of whom 17 had glaucoma and 8 were controls. Significant associations between quadrant binocular VF sensitivities and fMRI responses were found in the occipital pole ROIs (p = 0.033) and the calcarine ROIs (p = 0.045). In glaucoma severity subgroup analysis, retinal nerve fiber layer (RNFL) thickness was associated with the BOLD response of the calcarine and occipital pole ROIs (p = 0.002 and 0.026, respectively). The initial and asymmetrical glaucoma subgroups had similar binocular VF sensitivities and RNFL thicknesses, but distinct BOLD responses.

Conclusions: The response of the visual cortex to binocular stimulation was associated with binocular VF sensitivity. RNFL thickness was associated with the BOLD response of the calcarine and occipital pole ROIs.

No MeSH data available.


Related in: MedlinePlus

Polar angle visual stimuli used during functional magnetic resonance imaging scanning.
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pone.0126362.g002: Polar angle visual stimuli used during functional magnetic resonance imaging scanning.

Mentions: We obtained T2*-weighted BOLD images (GE-EPI, TR/TE/FA/GAP/VOXEL = 2,000 ms/30 ms/83°/0.5 mm/3×3×3 mm3) via fMRI. A binocular system was used to present visual stimuli. The scan frequency was 85 Hz, at 2.3 min of arc, and the total visual field extended 30° horizontally and 23° vertically (http://www.nordicneurolab.com; NNL, Norway). The fMRI paradigm was a polar angle stimulus consisting of a rotating wedge, featuring a contrast-reversing checkerboard pattern of 8 Hz, and 100% contrast, rotating clockwise around a fixation target (Fig 2). This was superimposed on a homogeneous gray background of the mean intensity of the checkerboard stimulus. The stimulus was presented bilaterally over three cycles of 60 s each, and, during the rest phase, each individual was instructed to fixate on a small central dot on the gray background screen. The system was controlled and synchronized by an opto-electrical trigger controlled by the RF signal from the MR system (Zurc&Zurc, São Paulo, Brazil) running in-house software. During stimulus presentation, the subjects were instructed to fixate on a target at the center of the screen and to press a button whenever the target changed (from a cross to a point and vice-versa), to maintain fixation; this ensured that the participants focused on the centers of their VFs. Each visual stimulus activated a specific area of the occipital cortex, creating traveling waves of neural activity in the visual cortex. For example, when a stimulus was presented to the superior right quadrant, the left occipital pole and left inferior calcarine region were activated. All of the subjects were closely monitored during fMRI examination.


Evaluation of Glaucomatous Damage via Functional Magnetic Resonance Imaging, and Correlations Thereof with Anatomical and Psychophysical Ocular Findings.

Gerente VM, Schor RR, Chaim KT, Felix Mde M, Ventura DF, Teixeira SH, Lottenberg CL, Amaro E, Paranhos A - PLoS ONE (2015)

Polar angle visual stimuli used during functional magnetic resonance imaging scanning.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4430279&req=5

pone.0126362.g002: Polar angle visual stimuli used during functional magnetic resonance imaging scanning.
Mentions: We obtained T2*-weighted BOLD images (GE-EPI, TR/TE/FA/GAP/VOXEL = 2,000 ms/30 ms/83°/0.5 mm/3×3×3 mm3) via fMRI. A binocular system was used to present visual stimuli. The scan frequency was 85 Hz, at 2.3 min of arc, and the total visual field extended 30° horizontally and 23° vertically (http://www.nordicneurolab.com; NNL, Norway). The fMRI paradigm was a polar angle stimulus consisting of a rotating wedge, featuring a contrast-reversing checkerboard pattern of 8 Hz, and 100% contrast, rotating clockwise around a fixation target (Fig 2). This was superimposed on a homogeneous gray background of the mean intensity of the checkerboard stimulus. The stimulus was presented bilaterally over three cycles of 60 s each, and, during the rest phase, each individual was instructed to fixate on a small central dot on the gray background screen. The system was controlled and synchronized by an opto-electrical trigger controlled by the RF signal from the MR system (Zurc&Zurc, São Paulo, Brazil) running in-house software. During stimulus presentation, the subjects were instructed to fixate on a target at the center of the screen and to press a button whenever the target changed (from a cross to a point and vice-versa), to maintain fixation; this ensured that the participants focused on the centers of their VFs. Each visual stimulus activated a specific area of the occipital cortex, creating traveling waves of neural activity in the visual cortex. For example, when a stimulus was presented to the superior right quadrant, the left occipital pole and left inferior calcarine region were activated. All of the subjects were closely monitored during fMRI examination.

Bottom Line: Binocular VF in each quadrant was determined using an integrated method.The response of the visual cortex to binocular stimulation was associated with binocular VF sensitivity.RNFL thickness was associated with the BOLD response of the calcarine and occipital pole ROIs.

View Article: PubMed Central - PubMed

Affiliation: Ophthalmology Department, Federal University of São Paulo, São Paulo, Brazil; Hospital Israelita Albert Einstein, São Paulo, Brazil.

ABSTRACT

Purpose: To evaluate the functional magnetic resonance imaging (fMRI) response to binocular visual stimulation and the association thereof with structural ocular findings and psychophysical test results in patients with glaucoma, and controls.

Methods: Cross-sectional study. Participants underwent a complete ophthalmic examination, including Humphrey 24-2 visual field (VF) testing and optical coherence tomography. Binocular VF in each quadrant was determined using an integrated method. Patients with glaucoma were assigned to three subgroups: initial, asymmetrical and severe glaucoma. Regions of interest (ROIs) were determined anatomically. fMRI (3 T) was performed using a bilaterally presented polar angle stimulus, and the accompanying changes in blood oxygen level-dependent (BOLD) signals were obtained from the occipital poles and calcarine ROIs. We used generalized estimation equation models to compare anatomical and functional data between the groups.

Results: A total of 25 subjects were enrolled, of whom 17 had glaucoma and 8 were controls. Significant associations between quadrant binocular VF sensitivities and fMRI responses were found in the occipital pole ROIs (p = 0.033) and the calcarine ROIs (p = 0.045). In glaucoma severity subgroup analysis, retinal nerve fiber layer (RNFL) thickness was associated with the BOLD response of the calcarine and occipital pole ROIs (p = 0.002 and 0.026, respectively). The initial and asymmetrical glaucoma subgroups had similar binocular VF sensitivities and RNFL thicknesses, but distinct BOLD responses.

Conclusions: The response of the visual cortex to binocular stimulation was associated with binocular VF sensitivity. RNFL thickness was associated with the BOLD response of the calcarine and occipital pole ROIs.

No MeSH data available.


Related in: MedlinePlus