A Novel Implantable Glaucoma Valve Using Ferrofluid

Purpose To present a novel design of an implantable glaucoma valve based on ferrofluidic nanoparticles and to compare it with a well-established FDA approved valve. Setting: Massachusetts Eye & Ear Infirmary, Boston, USA. Methods: A glaucoma valve was designed using soft lithography techniques utilizing a water-immiscible magnetic fluid (ferrofluid) as a pressure-sensitive barrier to aqueous flow. Two rare earth micro magnets were used to calibrate the opening and closing pressure. In-vitro flow measurements were performed to characterize the valve and to compare it to Ahmed™ glaucoma valve. The reliability and predictability of the new valve was verified by pressure/flow measurements over a period of three months and X-ray diffraction (XRD) analysis over a period of eight weeks. In vivo assessment was performed in three rabbits. Results: In the in vitro experiments, the opening and closing pressures of the valve were 10 and 7 mmHg, respectively. The measured flow/pressure response was linearly proportional and reproducible over a period of three months (1.8 µl/min at 12 mmHg; 4.3 µl/min at 16 mmHg; 7.6 µl/min at 21 mmHg). X-ray diffraction analysis did not show oxidization of the ferrofluid when exposed to water or air. Preliminary in vivo results suggest that the valve is biocompatible and can control the intraocular pressure in rabbits. Conclusions: The proposed valve utilizes ferrofluid as passive, tunable constriction element to provide highly predictable opening and closing pressures while maintaining ocular tone. The ferrofluid maintained its magnetic properties in the aqueous environment and provided linear flow to pressure response. Our in-vitro tests showed reliable and reproducible results over a study period of three months. Preliminary in-vivo results were very promising and currently more thorough investigation of this device is underway

of the Boston Keratopros-thesis

Purpose: We tested the feasibility of using titanium to enhance adhesion of the Boston Keratoprosthesis (B-KPro), ultimately to decrease the risk of implant-associated complications. Methods: Cylindrical rods were made of poly(methyl methacrylate) (PMMA), PMMA coated with titanium dioxide (TiO 2 ) over a layer of polydopamine (PMMA TiO2 ), smooth (Ti) and sandblasted (Ti SB ) titanium, and titanium treated with oxygen plasma (Ti ox and Ti SBox ). Topography and surface chemistry were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Adhesion force between rods and porcine corneas was measured ex vivo. Titanium sleeves, smooth and sandblasted, were inserted around the stem of the B-KPro and implanted in rabbits. Tissue adhesion to the stem was assessed and compared to an unmodified B-Kpro after 1 month. Results: X-ray photoelectron spectroscopy demonstrated successful deposition of TiO 2 on polydopamine-coated PMMA. Oxygen plasma treatment did not change the XPS spectra of titanium rods (Ti and Ti SB ), although it increased their hydrophilicity. The materials did not show cell toxicity. After 14 days of incubation, PMMA TiO2 , smooth titanium treated with oxygen plasma (Ti ox ), and sandblasted titanium rods (Ti SB , Ti SBox ) showed significantly higher adhesion forces than PMMA ex vivo. In vivo

Keratoprosthesis: A Review of Recent Advances in the Field

Since its discovery in the years of the French Revolution, the field of keratoprostheses has evolved significantly. However, the path towards its present state has not always been an easy one. Initially discarded for its devastating complications, the introduction of new materials and the discovery of antibiotics in the last century gave new life to the field. Since then, the use of keratoprostheses for severe ocular surface disorders and corneal opacities has increased significantly, to the point that it has become a standard procedure for corneal specialists worldwide. Although the rate of complications has significantly been reduced, these can impede the long-term success, since some of them can be visually devastating. In an attempt to overcome these complications, researchers in the field have been recently working on improving the design of the currently available devices, by introducing the use of new materials that are more biocompatible with the eye. Here we present an update on the most recent research in the field

Keratoprosthesis: A Review of Recent Advances in the Field

Since its discovery in the years of the French Revolution, the field of keratoprostheses has evolved significantly. However, the path towards its present state has not always been an easy one. Initially discarded for its devastating complications, the introduction of new materials and the discovery of antibiotics in the last century gave new life to the field. Since then, the use of keratoprostheses for severe ocular surface disorders and corneal opacities has increased significantly, to the point that it has become a standard procedure for corneal specialists worldwide. Although the rate of complications has significantly been reduced, these can impede the long-term success, since some of them can be visually devastating. In an attempt to overcome these complications, researchers in the field have been recently working on improving the design of the currently available devices, by introducing the use of new materials that are more biocompatible with the eye. Here we present an update on the most recent research in the field

Oral mucosa for reconstructive surgery in a case of severe inflammatory necrotizing sclero-uveitis

The purpose of this case is to show the efficacy of buccal mucosa as an alternative to treat a case of severe necrotizing sclero-uveitis (NSU) associated with ocular perforation. We show a severe inflammatory NSU case that did not improve with topical treatment and scleral patch. We performed a buccal mucosa graft taken from the lower lip with excellent functional and anatomical result, with no signs of relapse of the NSU after 2 years of follow-up. Buccal mucosa can be a safe, useful, and effective alternative for the reconstruction of the scleral wall

A prototype implantable ferromagnetic glaucoma valve (ferrovalve).

<p>Size comparison with one US cent coin (left), the tip of a pen (center) and a ruler of 1 cm scale (right). The size of the valve is 2.8×4.7×2.7 mm in Length x Width x Height. You can also distinguish the circular PDMS peg on the tube for scleral suturing.</p

Representation of the ferrofluidic valve architecture.

<p>(a) Enlarged photograph of the valve. An adjustable micro magnet (left), the capillary with the ferrofluid (center), and the fixed micro magnet (right). (b)Schematic diagram of the ferromagnetic valve.</p

A silicon wafer with 100 µm height features of negative SU-8 photoresist.

<p>The design was used as a master mold for the valve.D.</p

Contact angle measurements of a water droplet on non-coated (left), PEG-silane coated (center) and fluorosilane coated glass slides (right).

<p>Contact angle measurements of a water droplet on non-coated (left), PEG-silane coated (center) and fluorosilane coated glass slides (right).</p

Stability analysis of magnetite Fe3O4 nano-particles exposed to water and air exposure using X-ray diffraction analysis.

<p>(a) Top figure: X-ray diffraction analysis (XRD) of the ferrofluid pre-exposure to water and air. The 2θ peaks at 30° and 35.5° are characteristic of magnetite Fe₃O₄. (b) Bottom figure: X-ray diffraction analysis (XRD) of the ferrofluid post-exposure to water and air for 8 weeks. The 2θ peaks at 30° and 35.5° are characteristic of magnetite Fe₃O₄. No oxidization was observed on the ferromagnetic nano-particles.</p