Creep compliance rheology with a probe-like cylindrical geometry.

Background: Rheology experiments have been performed on the vitreous humor, a soft gel that rests inside of the eye, to study its viscoelastic behavior and underlying macromolecular structure. A significant challenge for experimentalists is preserving the macromolecular structure when removing vitreous from in vivo conditions.

Objective: We have developed a novel probe-like rheometer geometry that allows us to perform shear rheology experiments on the vitreous humor in situ.

Comparison of occlusion break responses and vacuum rise times of phacoemulsification systems.

Background: Occlusion break surge during phacoemulsification cataract surgery can lead to potential surgical complications. The purpose of this study was to quantify occlusion break surge and vacuum rise time of current phacoemulsification systems used in cataract surgery.

Methods: Occlusion break surge at vacuum pressures between 200 and 600 mmHg was assessed with the Infiniti® Vision System, the WhiteStar Signature® Phacoemulsification System, and the Centurion® Vision System using gravity-fed fluidics.

Effect of cut rates on fluidic behavior of chopped vitreous.

Purpose: To analyze the viscoelastic properties of the chopped vitreous at different cut rates to better understand complex fluidic behavior of chopped vitreous during vitrectomy.

Methods: Twenty- and 25-gauge cutters were used to cut 107 porcine eyes at different cut rates of 500, 1000, 1500, 2000, and 2500 cuts per minute with a fixed vacuum pressure of 500 mmHg. Each sample was immediately tested using a shear rheometer to obtain its rheologic properties.

Effect of surface mobility on the uniformity of a thin film under a bubble.

The shape of a soap bubble placed on a solid surface is familiar to everyone-a thin hemispherical dome that thickens near the solid surface. This structure is stabilized by the balance between the film's elasticity, provided by surfactant molecules, and the pressure inside the bubble. However, there is also a soap film on the flat solid surface that has been mostly ignored in previous studies; its thickness is typically assumed to be constant or varying monotonically.

Rheology of the vitreous gel: effects of macromolecule organization on the viscoelastic properties.

The macromolecular organization of vitreous gel is responsible for its viscoelastic properties. Knowledge of this correlation enables us to relate the physical properties of vitreous to its pathology, as well as optimize surgical procedures such as vitrectomy. Herein, we studied the rheological properties (e.