Synchronous functional magnetic resonance eye imaging, video ophthalmoscopy, and eye surface imaging reveal the human brain and eye pulsation mechanisms

• Main Authors: Seyed-Mohsen, Ebrahimi, Johanna, Tuunanen, Ville, Saarela, Marja, Honkamo, Niko, Huotari, Lauri, Raitamaa, Vesa, Korhonen, Heta, Helakari, Mika, Kaakinen, Lauri, Eklund, Vesa, Kiviniemi
• Format: Journal Article
• Language: English
• Published: 25-04-2023
• Subjects: Physics - Medical Physics
• DOI: 10.48550/arxiv.2304.12629

Recent research shows the eye has a paravascular solute transport pathway
driven by physiological pulsations resembling the brain. we developed
synchronous multimodal imaging tools aimed at measuring the driving pulsations
of the human eye. We used an eye-tracking functional eye camera (FEC)
compatible with magnetic resonance imaging (MRI) for measuring eye surface
pulsations. Special optics enabled the integration of the FEC with a magnetic
resonance compatible video ophthalmoscopy (MRcVO) for simultaneous retinal
imaging along with functional eye MRI imaging (fMREye) reflecting BOLD (blood
oxygen level dependent) contrast. Upon optimizing the fMREye parameters, we
thus measured the power of the physiological (vasomotor, respiratory, and
cardiac) eye and brain pulsations by fast Fourier transform (FFT) power
analysis. The human eye proved to pulsate in all three physiological pulse
bands, most prominently in the respiratory (RESP) band. The FFT power means of
physiological pulsation for two adjacent slices was significantly higher than
in one-slice scans (RESP1 .vs RESP2; df = 5, p = 0.0174). FEC and MRcVO
confirmed the respiratory pulsations at the eye surface and retina. we conclude
that the human eye has three pulsation mechanisms, and multimodal imaging
offers non-invasive monitoring of their effects in driving eye fluidics.