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Artificial Cornea (artificial + cornea)

Distribution by Scientific Domains

Medical Sciences	75%

Selected Abstracts

Apatite Deposition on NaOH-Treated PEEK and UHMWPE Films for Sclera Materials in Artificial Cornea Implants,

ADVANCED ENGINEERING MATERIALS, Issue 7 2010
Monica Pino
Abstract Cornea implants consist of a clear optic portion with a surrounding ring known as the skirt, which needs to integrate with the sclera. However, currently used skirt materials lead to poor tissue integration. Improvements in this respect may be achieved by using a bioactive skirt material that adapts to the metabolic activity of the cornea. Polyether etherketone (PEEK) and ultra-high molecular weight polyethylene (UHMWPE) might provide interesting alternatives, if they can be rendered bioactive. We, therefore, investigated the potential of surface-modifying PEEK and UHMWPE films through the use of a two-step treatment. This process involved a suitable chemical surface modification (via immersion in NaOH), with subsequent formation of apatite layers on the polymers' surfaces through exposure to supersaturated simulated body fluid (1.5 SBF). In the present work the effect of 5 and 10,M NaOH on formation of the apatite layer has been investigated with regard to wettability and topography features. In addition, the chemical stability of the apatite layer formed has been analyzed. Our data demonstrate that with an increase in NaOH concentration the wettability of the polymer increased, whilst some changes to the polymer film topography (increase/decrease in roughness) were observed. Most beneficially, the apatite layer that subsequently was grown on pre-treated PEEK and UHMWPE films through immersion in 1.5 SBF contained phosphate and carbonate ions, in similar ratios to those found in the apatite in dentine, thus, promising good in vivo bioactivity of these polymer films,a necessity if they are to be integrated into artificial cornea. [source]

History of and necessity for KPros

ACTA OPHTHALMOLOGICA, Issue 2009
C LIU
The history of keratoprostheses goes back over 200 years. There was a resurgence in interest in the second half of the twentieth century as it was recognised that keratoplasty could not solve all types of corneal blindness. Many devices have been described but few have survived. Corneal transplantation is complicated by graft rejection and astigmatism. There is also a problem with adequate supply, and there is a risk of transmission of infection. There is a desire for an artificial cornea which surpasses cadaveric transplantation. There is much ongoing work, but the majority of clinical work on keratoprostheses are for corneal blindness not amenable to cadaveric grafts. These can be separated into two main groups. The wet blinking eye which have had multiple graft failures, and the dry eye with a keratinised ocular surface which may also have a deficiency in lid cover. The approaches to these are quite different. [source]

Boston type I in pediatric patients

ACTA OPHTHALMOLOGICA, Issue 2009
J AQUAVELLA
Purpose To present a retrospective review of keratoprosthetic implantation and retention in patients with congenital corneal opacities. Methods Pediatric patients younger than seven years old, the average age of permanent visual loss from understimulation of the visual cortex, were selected from a single center Boston Type I keratoprosthesis database and categorized by 1) primary diagnosis, 2) short-term visual outcome, and 3) post-operative complications. Results Seventeen patients, with an age range of 41 days up to 6 years, were selected from a database of over one hundred and forty patients. Six had a primary diagnosis of sclerocornea and eleven had Peter's anomaly. Visual outcome after one year improved in fourteen of the patients, with patients who previously could not detect light to subsequently being able to fixate and follow or even read allen cards. The remaining three patients showed no improvement in visual acuity but also no worsening from their baseline condition. In terms of post-operative complications of the optic, two had retroprosthetic membrane formation, and another patient required replacement of the keratoprosthesis due to phthisis and optic melting. From a retinal standpoint, four patients had retinal detachments. There were no cases of choroidal hemorrhaging or hypotony in these patients. Conclusion Based on visual outcome, the Boston Type I keratoprosthesis is a safe and effective procedure for patients with congenital corneal opacities. With great retention, the artificial cornea is a viable option for prevention of amblyopia. Due to comorbidities such as congenital cataracts, congenital glaucoma, and retinal detachments, it is crucial to have glaucoma and vitreo-retinal surgeons on hand when managing and implanting keratoprosthesis in a pediatric population. [source]

Keratoprostheses in clinical practice , a review

CLINICAL & EXPERIMENTAL OPHTHALMOLOGY, Issue 2 2010
Ahmed Gomaa FRCS PhD
Abstract The search for a substitute for the natural cornea dates back more than 200 years. Although several devices have been developed and trialled, very few have had successful long-term results and continue in regular clinical use. Keratoprosthesis (KPro) surgery is complex and should be performed in centres with an experienced multidisciplinary team. Currently available KPro devices range from the totally synthetic, such as the Boston KPro, to the totally biological tissue-engineered artificial cornea. The osteo-odonto keratoprothesis combines a synthetic optic with a biological haptic. All keratoprostheses have significant limitations, although visual improvement is possible with each of the devices in clinical use today. This review discusses these devices with emphasis on their indications, surgical techniques and results, before briefly exploring emerging devices and innovative approaches for the future. [source]