Abstract
Purpose :
Vitreous floaters cause vision disturbance that worsens during reading and driving due to vitreous displacement of opacities into the optical axis during eye movement. However, vitreous movement dynamics have not been sufficiently studied. On T1-weighted magnetic resonance imaging (MRI), vitreous is hypointense to the lens, but during displacement becomes hyperintense. This study characterized vitreous displacement with eye movement using real-time MRI (rtMRI).
Methods :
Ten subjects (6♂, 4♀, aged 36.7 ± 12.5 yrs) with varying refractive errors (2 low hyperopes, 4 emmetropes, 4 myopes) underwent rtMRI while moving their eyes between primary, up, and downgaze. A T1-weighted gradient echo sequence and rapid image acquisition recorded vitreous movement in vivo. Each scan captured 90 frames over 77 seconds, and two periods of oscillation were imaged per eye. There was variability in the speed of eye movements, so angular velocity for each eye movement was determined from the scans and changes in rtMRI signal intensity recorded (4 measurements/orbit). Correlations between signal intensity and angular velocity of eye rotation were assessed using (Spearman’s rank correlation), and associations with axial length evaluated (Student’s T-test).
Results :
The hyperintense vitreous signal on rtMRI follows rotation of the globe with a whirled appearance that begins adjacent to the sclera, decaying toward the center. There was a strong positive correlation between the rtMRI signal intensity and the angular velocity of the globe (R = 0.88, p < 0.0001). With signal intensity normalized for the speed of eye movements, there was a difference between myopes (3.98 ± 1.32) and non-myopes (3.20 ± 0.88, p = 0.07). Longer axial lengths trended towards higher vitreous signal intensity with eye movement (Figure).
Conclusions :
rtMRI detected signal hyperintensity produced by vitreous displacement during eye movement. The intensity of the signal increased with faster eye movement, making this a potentially useful way to evaluate vitreous rheology in conditions such as myopic vitreopathy and aging, especially with PVD. Myopic eyes trended to greater vitreous displacement than non-myopes, consistent with known fibrous liquefaction of vitreous in axial myopia (AJO 224:246-53, 2021). Future study of vitreous displacement during horizontal eye movement can provide clinical metrics useful for research, patient evaluations, and outcome measures of treatment.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.