polymers used in soft contact lenses
- 최초 등록일
- 2008.12.11
- 최종 저작일
- 2008.12
- 3페이지/ MS 워드
- 가격 1,500원
소개글
polymers used in soft contact lenses; Lotraflicon A which is composed of PDMS or PEPE which is copolymerized with TRIS and DMA monomer
목차
1. intro
2-1. permeability to oxygen
2-2. Hydrophilicity and lipophobicity
2-3. Hydrophobicity
3. Conclusion
본문내용
1. Intro
Ophthalmic compatibility of a contact lens on the eye requires the lens maintain a stable, continuous tear film for clear vision, is resistant to deposition of tear film components, sustains normal hydration, is permeable to oxygen to maintain normal corneal metabolism, is permeable to ions to maintain movement and to be nonirritating and comfortable. Therefore, the lens must have excellent surface characteristics being neither hydrophobic nor lipophilic and must possess the appropriate bulk polymer composition and morphology to be successful. (P.C. Nicolson, 2001:3273–3283) Two polymers are now commercialized, which are Lotrafilcon A and Balafilcon A. Lotraflicon A is composed of PDMS or PEPE which is copolymerized with TRIS and DMA monomer. Balafilcon A is made up of tris-(trimethylsiloxy-) silyl-propylvinyl carbamate (TRIS-VC), a vinyl carbonate functional PDMS macromer (Fig. 14), co-polymerized with NVP and the vinyl carbamate derived from b-alanine. (USPS Dictionary of USAN and International Drug Names, op.cit., p. 75.)
2-1. Permeability to oxygen
Permeability to oxygen is a key performance characteristic for contact lenses. The expression Dk has become universally accepted, as the term referring to the intrinsic property of a material to transport oxygen through its bulk; it is thickness independent. The term Dk=t (or Dk=l) refers to the oxygen transport properties of a contact lens of thickness t (or l), in mm and is called oxygen transmissibility. (P.C. Nicolson, 2001:3273–3283)
참고 자료
1. K.unzler J, Ozark R. US Patent 5,321,108, 1994.
2. Lai Y. The role of bulky polysiloxanylalkyl methacrylates in oxygen-permeable hydrogel materials. J Appl Polym Sci 1996;56:31724
3. P.C. Nicolson, J. Vogt / Biomaterials 22 (2001) 32733283
4. USPS Dictionary of USAN and International Drug Names, op.cit., p. 75
5. www.siliconehydrogels.org/editorials/jun_07.asp
6. http://en.wikipedia.org/wiki/ Pdms