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ARTIFICIAL CORNEAS_Aditi_Bandyopadhyay


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Unformatted text preview: ARTIFICIAL CORNEAS MEEN 3344 Presentation by: Aditi Bandyopadhyay CHARACTERISTICS OF AN ARTIFICIAL CORNEA Withstand intraocular pressure Be transparent Have an appropriate curvature Have a suitable refractive index Have sufficient tensile strength to allow surgical manipulation and fixation. 1 Figure 1. Dohlman Device MATERIALS USED TO MAKE ARTIFICIAL CORNEAS Poly (methyl methacrylate) (PMMA) Poly 2-hydroxyethyl methacrylate (PHEMA) hydrogels Poly(vinyl alcohol) (PVA) Figure 2. Artificial cornea Photo credits: National Research Council of Canada CHARACTERISTICS OF PMMA Transparent and colorless 92% transmission of visible light Glassy polymer with an amorphous structure Very low water absorption capacity The refractive index ranges from 1.49 to 1.51 depending on the type. High mechanical strength High Young's modulus Good hardness with low elongation at break. Does not shatter or rupture Highly scratch resistant. 3 Figure 3. Chemical structure of PMMA REFERENCES 1. 2. 3. 4. 5. Chirila. T. V., Hicks C. R., Dalton. P.D., Vijayasekaran. S., Lou. X., Hong. Y., Clayton. A.B., Ziegelaar. B W., Fitton. J.H., Platten. S., Crawford. G.J., Constable. I.J. Aritificial Cornea, Prog. Polym. Sci., 1998, 23, 447-473 Kobayashi. H., Kato. M., Taguchi. T., Ikoma. T., Miyashita. H., Shimmura. S., Tsubota. K., Tanaka. J., Collagen immobilized PVA hydrogel-hydroxyapatite composites prepared by kneading methods as a material for peripheral cuff of artificial cornea, Material Science and Engineering C, 2004, 24, 729-735 http://www.tangram.co.uk/. Last updated on 08/28/06 Hicks. C. R., Fitton. J. H., Chirila. T V., Crawford. G. J., Constable. I.J., Keratoprostheses: Advancing toward a true artificial cornea, Survey of ophthalmology, 1997, 42 http://depts.washington.edu/chemeng ...
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