ARTIFICIAL CORNEAS MEEN 3344 Presentation by: Aditi Bandyopadhyay

CHARACTERISTICS OF AN ARTIFICIAL CORNEA Withstand intraocular pressure Withstand intraocular pressure Be transparent Be transparent Have an appropriate curvature Have an appropriate curvature Have a suitable refractive index Have a suitable refractive index Have sufficient tensile strength to allow surgical manipulation and fixation. 1 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 (methyl methacrylate) (PMMA) Poly 2-hydroxyethyl methacrylate (PHEMA) hydrogels Poly 2-hydroxyethyl methacrylate (PHEMA) hydrogels Poly(vinyl alcohol) (PVA) Poly(vinyl alcohol) (PVA) Figure 2. Artificial cornea Photo credits: National Research Council of Canada

CHARACTERISTICS OF PMMA Transparent and colorless Transparent and colorless 92% transmission of visible light 92% transmission of visible light Glassy polymer with an amorphous structure Glassy polymer with an amorphous structure Very low water absorption capacity Very low water absorption capacity The refractive index ranges from 1.49 to 1.51 depending on the type. The refractive index ranges from 1.49 to 1.51 depending on the type. High mechanical strength High mechanical strength High Young's modulus High Young's modulus Good hardness with low elongation at break. Good hardness with low elongation at break. Does not shatter or rupture Does not shatter or rupture Highly scratch resistant. 3 Highly scratch resistant. 3 Figure 3. Chemical structure of PMMA

REFERENCES 1. 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, 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, Last updated on 08/28/ 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,