title: Ultrasound imaging velocimetry of the human vitreous.
abstract: Knowledge of vitreous motion in response to saccades is a prerequisite for understanding vitreous rheology. Purpose of present paper is to introduce Ultrasound Image Velocimetry of the human eye, measure scleral and vitreous velocity fields and test the reproducibility of the proposed technique. Twelve patients with varying diagnosis underwent Ocular Dynamic Ultrasound; scleral angular velocity (V(S)) was measured by 2 different operators and reproducibility calculated. Squared velocity of the vitreous (E), which is representative of kinetic energy per unit mass, was computed from velocity. The time evolution of the energy of the vitreous was described by its spatial average (E(S)), whereas spatial distribution was described by its time average (E(T)). Peak and average E(S), the ratio K(p) of the peak of the spatially averaged kinetic energy per unit mass to the maximum squared scleral angular velocity, vitreous motion onset time (T(O)) and vitreous motion decay time (T(D)) were also defined. Inter-operator reproducibility coefficient was 0.043 and correlation between operators was significant. V(S), peak and average E(S), K(p) ratio and T(D) differed among patients but not among operators. V(S) correlated with E(S) and T(D). E(S) and T(D) but not V(S), were significantly different in patients with Posterior Vitreous Detachment. Patients with retinal detachment showed significantly higher V(S) and E(S). K(p) was inversely correlated to age and refraction. Measures proved accurate and reproducible. E is related to V(S), retinal traction and mechanical stimulation. Identified variables varied with age, refraction pathologic conditions.
authors.affiliation: Ospedale Oftalmico di Roma, Rome, Italy. tommaso.rossi@usa.net
authors.forename: Tommaso
authors.initials: T
authors.lastname: Rossi
authors.forename: Giorgio
authors.initials: G
authors.lastname: Querzoli
authors.forename: Giacomo
authors.initials: G
authors.lastname: Pasqualitto
authors.forename: Mario
authors.initials: M
authors.lastname: Iossa
authors.forename: Luca
authors.initials: L
authors.lastname: Placentino
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Repetto
authors.forename: Alessandro
authors.initials: A
authors.lastname: Stocchino
authors.forename: Guido
authors.initials: G
authors.lastname: Ripandelli
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D005260:Female; D006801:Humans; D057446:Hydrodynamics; D008297:Male; D008875:Middle Aged; D012212:Rheology / Q000379:methods*; D012438:Saccades / Q000502:physiology; D012590:Sclera / Q000000981:diagnostic imaging / Q000502:physiology; D013997:Time Factors; D014463:Ultrasonography; D055682:Viscoelastic Substances; D014822:Vitreous Body / Q000737:chemistry* / Q000000981:diagnostic imaging*
chemical_list: D055682:Viscoelastic Substances