Validity of aerosolization detection with an air quality indicator in noncontact tonometry using corneal phantoms.

PrÉcis: Using a controlled experimental design with corneal phantoms, this study provides evidence of the lack of validity of a static air quality indicator, previously used to characterize aerosolization during dynamic noncontact tonometry.

Purpose: To evaluate the accuracy of aerosol concentrations reported by an air quality indicator (AQI) following an air puff from a noncontact tonometer using non-aerosolizing corneal phantoms.

Methods: Three rubber corneal phantoms of different stiffnesses were used to represent varying intraocular pressure (IOP) values.

The Shape of Corneal Deformation Alters Air Puff-Induced Loading.

To determine the dynamic modification of the load exerted on the eye during air-puff testing by accounting for the deformation of the cornea. The effect of corneal load alteration with surface shape () was characterized as an additional component of the load produced during the concave phase where the fluid outflow tangential to the corneal surface creates backward pressure. Concave phase duration ( ), maximum value ( ), and the area under -time curve ( ) are calculated for 26 keratoconic (KCN), 102 normal (NRL), and 29 ocular hypertensive (OHT) subjects.

Hydrodynamic Interaction Between Tear Film and Air Puff From Noncontact Tonometry.

Purpose: The purpose of this study was to investigate the mechanism of potential droplet formation in response to air puff deformation with two noncontact tonometers (NCTs).

Methods: Twenty healthy volunteers were examined using two NCTs, Ocular Response Analyzer and Corvis ST, and two contact tonometers, iCare and Tono-Pen. High-speed videos of the tear film response were captured with at spatial resolution of 20 microns/pixel at 2400 fps.

An in vitro evaluation of turbulence after transcatheter aortic valve implantation.

Background: This study aimed at assessment of post-transcatheter aortic valve (TAV) replacement hemodynamics and turbulence when a same-size SAPIEN 3 (Edwards Lifesciences Corp, Irvine, Calif) and Medtronic Evolut (Minneapolis, Minn) were implanted in a rigid aortic root with physiological dimensions and in a representative root with calcific leaflets obtained from patient computed tomography scans.

Methods: TAV hemodynamics were studied by placing a SAPIEN 3 26-mm and an Evolut 26-mm in rigid aortic roots and representative root with calcific leaflets under physiological conditions. Hemodynamics were assessed using high-fidelity particle image velocimetry and high-speed imaging.

Effect of Arched Leaflets and Stent Profile on the Hemodynamics of Tri-Leaflet Flexible Polymeric Heart Valves.

Polymeric heart valves (PHV) can be engineered to serve as alternatives for existing prosthetic valves due to higher durability and hemodynamics similar to bioprosthetic valves. The purpose of this study is to evaluate the effect of geometry on PHVs coaptation and hemodynamic performance. The two geometric factors considered are stent profile and leaflet arch length, which were varied across six valve configurations.

Heart Valves from Polyester Fibers vs. Biological Tissue: Comparative Study In Vitro.

Transcatheter aortic valve implantation (TAVI) has become a popular alternative technique to surgical valve replacement for critical patients. Biological valve tissue has been used in TAVI procedures for over a decade, with over 100,000 implantations to date. However, with only 6 years follow up, little is known about the long-term durability of biological tissue.

Reynolds shear stress for textile prosthetic heart valves in relation to fabric design.

The most widely implanted prosthetic heart valves are either mechanical or bioprosthetic. While the former suffers from thrombotic risks, the latter suffers from a lack of durability. Textile valves, alternatively, can be designed with durability and to exhibit hemodynamics similar to the native valve, lowering the risk for thrombosis.