Biologic keratoprosthesis materials.

Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA.
International Ophthalmology Clinics 02/2009; 49(1):1-9. DOI: 10.1097/IIO.0b013e3181924904
Source: PubMed
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    ABSTRACT: Purpose: We describe a technique to avoid decentration of the visual axis of the Boston type 1 keratoprosthesis (Kpro), performing 2 concentric trephinations with femtosecond laser. Methods: Two concentric side cuts were performed in a donor cornea using the 150-kHz Intralase™ FS laser. Within the same applanation procedure, an 8.5-mm-diameter anterior side cut was performed, followed by a concentric 3-mm-diameter anterior side cut. Results: The technique was successfully replicated in 7 cases. Conclusions: Femtosecond laser-assisted double trephination results in a correctly prepared donor cornea, and in an inner side precisely matched with the prosthesis. At the end of the surgery, the Kpro was correctly centered.
    European journal of ophthalmology 12/2013; 24(2). DOI:10.5301/ejo.5000387 · 1.06 Impact Factor
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    ABSTRACT: In the present study, novel biomimetic composite scaffolds with a composition similar to that of natural bone were prepared, using nano-hydroxyapatite, collagen, and phosphatidylserine. The scaffolds possess an interconnected porous structure with a porosity of 84%. The pore size ranges from several micrometers up to about 400 μm. In-vitro studies in simulated body fluids showed that the morphologies of the products derived from mineralization can be regulated by the extracellular matrix components of the scaffolds; this in turn leads to creation of a large number of hydroxyapatite crystals on the scaffold surface. The regulatory properties of collagen and phosphatidylserine also influenced the cell response to the composite scaffolds. MC3T3-E1 cells attached and spread on the surfaces of the materials and interacted with the substrates; this may be the result of charged groups on the composite materials. Radiological analysis suggested that calluses and bone bridges formed in defects within 12 weeks. These composite scaffolds may therefore be a suitable replacement in bone-tissue engineering.
    Chinese Science Bulletin 07/2012; 57(21). DOI:10.1007/s11434-012-5201-4 · 1.37 Impact Factor
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    ABSTRACT: PURPOSE: To demonstrate a mathematical algorithm for calculating the refractive power of keratoprostheses and to estimate vignetting effects. METHODS: A paraxial calculation scheme based on vergence transformation is developed for determination of the front surface radius or front surface refractive power of a Boston type I or II keratoprosthesis based on the design data of the manufacturer. A concept for derivation of lateral magnification (ratio of image size to slope of the incident ray) is presented based on 2 × 2 matrix representation of the eye. For estimation of vignetting effects, numerical ray tracing was used and the maximum half field angle and half luminance half field angle was extracted. RESULTS: Simulation calculations were performed in MATLAB. The front surface radius or refractive power is given in explicit form as a function of axial length, target refraction, as well as the principal design data of the keratoprosthesis such as posterior refractive power, length, or refractive index. With variation of the back surface radius it was shown that lateral magnification can be modulated e.g. to match the magnification of the fellow eye. The Boston type I does not restrict the field angle substantially, whereas type II shows significant vignetting effects. CONCLUSION: We present a strategy on the calculation of keratoprostheses and variation of the design (e.g. back surface curvature) to help to avoid aniseikonia in case of binocular vision (e.g. one phakic eye and one with keratoprosthesis).
    Ophthalmic and Physiological Optics 03/2013; 33(4). DOI:10.1111/opo.12046 · 2.66 Impact Factor