ARTIFICIAL CORNEAS

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ARTIFICIAL CORNEAS

• MEEN 3344
• Presentation by
• Aditi Bandyopadhyay

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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
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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
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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
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REFERENCES

• 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-hydroxyapati
  te 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