2008年11月9日星期日

Intraocular lens


History

First permanent insertion of intraocular lens 8 February 1950
Sir Harold Ridley was the first to successfully implant an intraocular lens on November 29, 1949, at St Thomas' Hospital at London. That first intraocular lens was manufactured by the Rayner company of Brighton, East Sussex, England from Perspex CQ made by ICI. It is said that idea of implanting an intraocular lens came to him after an intern asked him why he was not replacing the lens he had removed during cataract surgery. The first lenses used were made of glass, they were heavy and were prone to shatter during Nd:YAG capsulotomy. Plastic materials were used later, when Harold Ridley noticed that they were inert, after seeing pilots of World War II with pieces of shattered windshields in their eyes. The intraocular lens did not find widespread acceptance in cataract surgery until the 1970s, when further developments in lens design and surgical techniques had come about. Currently, more than a million IOLs are implanted annually in the United States.

Materials used for intraocular lenses

Please help improve this section by expanding itwith: reorganization, clarifications, better differentiation between the practices of different countries, and specific differences between PMMA, sillicone, and silicone acrylate. Further information might be found on the talk page or at requests for expansion. (January 2008)
Polymethylmethacrylate (PMMA) was the first material to be used successfully in intraocular lenses. British ophthalmologist Sir Harold Ridley observed that Royal Air Force pilots who sustained eye injuries during World War II involving PMMA windshield material did not show any rejection or foreign body reaction. Deducing that the transparent material was inert and useful for implantation in the eye, Ridley designed and implanted the first intraocular lens in a human eye.
Advances in technology have brought about the use of silicone and acrylic, both of which are soft foldable inert materials. This allows the lens to be folded and inserted into the eye through a smaller incision. PMMA and acrylic lenses can also be used with small incisions and are a better choice in people who have a history of uveitis, have diabetic retinopathy requiring vitrectomy with replacement by silicone oil or are at high risk of retinal detachment. Acrylic is not always an ideal choice due to its added expense. Latest advances include IOLs with square-edge design, non-glare edge design and yellow dye added to the IOL.

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