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Refractive anomalies and visual activation in functional magnetic resonance imaging (fMRI): a versatile and low-cost
Gregor-K Elbel1, Christian Kaufmann, Stefan Schaefers
1Max Planck Institute of Psychiatry, Magnetic Resonance Study Group, Munich, Germany.
Purpose:
To develop a magnetic resonance (MR)-compatible, versatile, easy-to-use, and low-cost device for refractive correction.
Materials And Methods:
We retrospectively evaluated the application and practicability of the refractive correction in 110 subjects who had participated in various functional MR imaging (fMRI) studies with complex visual stimulation paradigms since the introduction of the MR-compatible lens frame at our site. The subjects consisted of 31 patients with Parkinson's disease (age range, 40-85; mean age, 63.2 years) and 79 healthy volunteers (age range, 18-79; mean age, 46.7 years).
Results:
In volunteers, experimentally induced myopia caused a substantial (>20%) reduction of the blood oxygenation level dependent (BOLD) response to a flickering dartboard.
Conclusion:
Refractive errors (and the resulting optical blur) may play a nonnegligible role as a possible interfering factor in fMRI experiments with visual stimuli. The MR-compatible frame (fitted with appropriate lenses) used in this study affords full refractive correction at reasonable cost and preparation time.