Implantation, intraocular

FDA approved intraocular injections include mio-tics, viscoelastics, and viscoadherents and an antiviral agent for intravitreal injection. The approved intraocular miotics, carbachol (Miostat ) and acetylcholine (Miochol ), are injected into the anterior chamber at the end of cataract surgery to constrict the pupil and allow the iris to cover the implanted intraocular lens. Carbachol is formulated in a BSS vehicle in sterile water for injection at a physiological pH... 

Iso 11979-2. Ophthalmic Implants—Intraocular Lens—Part 2 Optical Properties and Their Test Methods. Switzerland (1999). 

Surface-bound, neutral, hydrophilic polymers such as polyethers and polysaccharides dramatically reduce protein adsorption [26-28], The passivity of these surfaces has been attributed to steric repulsion, bound water, high polymer mobility, and excluded volume effects, all of which render adsorption unfavorable. Consequently, these polymer modified surfaces have proven useful as biomaterials. Specific applications include artificial implants, intraocular and contact lenses, and catheters. Additionally, the inherent nondenaturing properties of these compounds has led to their use as effective tethers for affinity ligands, surface-bound biochemical assays, and biosensors. 

Hydrophilic drugs, such as gentamicin, do not cross the blood-retinal barrier readily after systemic administration. After intravitreal administration they have a prolonged half-life of 24 hours or more in the vitreous humor.Their major route of exit is across the lens zonules and into the aqueous humor and then through the aqueous outflow pathways. For the vitreous to act as a depot for these drugs, the agents must be injected, introduced by iontophoresis, or slowly released by a surgically implanted intraocular device. 

Besides external contact lenses, there are surgically implanted intraocular contact lenses that are usually used to replace the eye s natural lens after cataract surgery these lenses are normally based on silicone or PMMA and lie outside the scope of this entry. 

Silicone elastomers have a long history of use in the medical field. They have been applied to cannulas, catheters, drainage tubes, balloon catheters, finger and toe joints, pacemaker lead wire insulation, components of artificial heart valves, breast implants, intraocular lenses, contraceptive devices, burn dressings and a variety of associated medical devices. A silicone reference material has been made available by the National Institutes of Health to equate the blood compatibility of different surfaces for vascular applications. This material is available as a silica-free sheet. Contact the Artificial Heart Program, NHBLI, NIH, Bethesda, Md. for further information. 

Implantable medical devices market (reconstructive joint replacemenfi spinal implants, cardiovascular implants, dental implants, intraocular lens and breast implants)— U.S. Industry analysis, size, share, trends, growth and forecast 2012-2018. Transparerwy market research. (2013). 

Antiadhesion applications Prevent bacterial adhesion to dental implants, intraocular lenses, and catheters... 

Afanasyeva and Bruch (1999) have applied the FTIP reflection method to investigate the surfaces of materials used for intraocular lenses (IOLs) in the production of implants that are non-toxic to the eye. In particular they studied passivated lens surfaces, which is a treatment which impedes the growth of cells upon the lens surface. Lenses made of PMMA and of sapphire were examined, and Figure 3.5 shows a typical IR spectrum in the 3000-2800 cm-1 wavenumber region. 

In the case of a novel product such as an intraocular implant, considerable discussion is included in the EPAR concerning the development, manufacture, and control of the product. In the particular case of one product,... 

Ganciclovir intraocular implant plus valganddovir 900 mg once daily until immune recovery from ART (Al)° Ganciclovir 5 mg/kg IV every 12 hours or foscarnet 180 mg/kg/day in two or three divided doses IV for 21 to 28 days (Bll)... 

Another example of a biomaterial is the intraocular lens, which have been commonly used to treat cataracts. They were traditionally made of inflexible materials, but more recently consist of poly(methyl methacrylate) and soft flexible materials such as silicone and acrylic. The first person to successfully implant an intraocular lens was Sir Harold Riley at the St Thomas Hospital in London in 1949. The first lenses were made of glass, were heavy, and carried several risks including infection, inflammation, loosening of the lens, lens rotation, and night time halos (Thompson, 2007). These problems, now less frequent, still occur today in a small fraction of more than one million intraocular lenses that are implanted annually in the USA. 

Class 11b, for example, urethral stents, insulin pens, devices supplying ionising radiation, prosthetic joint replacements, intraocular lenses, maxillofacial implants... 

Various gaseous (F-propane, SFe) and liquid (F-octane, F-decalin, F-perhydrophe-nanthren, mixed fluorocarbon-hydrocarbon diblocks, and fluorosilicones) F-com-pounds are being used as intraocular tamponades for use in vitreoretinal surgery [Chapter 9 by Rico-Lattes et a ., this volume]. Polymers with F-alkyl moieties are used in corneal inlays and implants and in intraocular lenses. 

Of the three physical properties covered in this chapter, optical properties have the least importance in composite and biological applications. This is not to say that there are no applications of optical properties in composites or biological materials. There are indeed, such as the use of birefringence in the analysis of stress distribution and fiber breakage in fiber-matrix composites [14] and in the development of materials for ophthalmic implants such as intraocular devices [15]. These topics are beyond the scope of this text, however, even as optional information, and introduce no new concepts from a material property standpoint. There are many interesting articles and... 

A 0.1% ophthalmic preparation is recommended for prevention of postoperative ophthalmic inflammation and can be used after intraocular lens implantation and strabismus surgery. A topical gel containing 3% diclofenac is effective for solar keratoses. Diclofenac in rectal suppository form can be considered for preemptive analgesia and postoperative nausea. In Europe, diclofenac is also available as an oral mouthwash and for intramuscular administration. 

Intraocular implant CMV retinitis treatment 4.5 mg every 5-8 months... 

Ganciclovir may be administered intravenously, orally, or via intraocular implant. The bioavailability of oral ganciclovir is poor. Cerebrospinal fluid concentrations are approximately 50% of those in serum. The elimination half-life is 4 hours, and the intracellular half-life is prolonged at 16-24 hours. Clearance of the drug is linearly related to creatinine clearance. Ganciclovir is readily cleared by hemodialysis. 

Intraocular implant (Vitrasert) 4.5 mg ganciclovir/implant Idoxuridine (Herplex)... 

The medical devices in category 4 of Table 1 are controlled in-process testing with critical specifications designed for individual products or a group of products and are implanted. The compatibility of product materials with tissue and cells, the stability of product in the implanted site, and the sterility of product should be key factors to assure the product safety. Intraocular lenses and pacemakers are included in this category. 

Ganciclovir may be administered intravenously, orally, or via intraocular implant. 

In patients with an intraocular implant, ganclovir is released into the vitreous cavity at a rate of... 

The primary potential adverse effects associated with the intraocular implant are vitreous... 

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