Ophthalmic Viscosurgery A Development

In 1970 at an international meeting of ophthalmic surgeons, one of the authors (E.A.B.) of this chapter reported his work on the use of purified hyaluronan solutions in eye surgery. The contents of this report, published in the following years (1-7), established that hyaluronan solutions, after being purified from proteins, nucleic acids, endotoxin, and other inflammatory agents, can be used in various surgical procedures, provided the solution has certain viscous and elastic properties. The report was the result of a decade of laboratory research (Boston Biomedical Research Institute), industrial development (Biotrics, Inc., Arlington, MA), and clinical studies in academic ophthalmology departments (Boston, Stockholm, Essen, Paris, Zurich). The biocompatibility of this product produced from human umbilical cord and rooster comb was tested in nearly 500 owl monkey eyes. Owl monkeys were used because their viscous vitreous is liquid, and half of it (1 ml) can be replaced by test solutions without causing traumatic injury to the eye. The clinical studies established the usefulness of the highly elastoviscous hya-luronan solutions as vitreous replacements in retinal detachment surgery and as viscoelastic tools for surgical manipulations. The same solutions were injected into the anterior chamber of human patients in keratoplasty, cataract surgery, and iri-dectomy. The rationale for using these highly elastoviscous hyaluronan solutions was that they should serve as a "mechanical buffer" between the retina and the gel vitreous, the cornea and lens, and the cornea and the vitreous in aphakic eyes. The same mechanical properties of the elastoviscous fluid made it a "soft tool" to manipulate sensitive tissues during surgery. An equally important reason for using hyaluronan in eye surgery was its effect on wound healing. Animal studies with this hyaluronan preparation showed that it prevented excessive fibrous tissue formation during wound healing (8). This effect is important after retinal detachment surgery, cataract surgery, and keratoplasty. HealonĀ®, the product that established ophthalmic viscosurgery, was developed by scientists who had long experience with the rheological properties, as well as the biological activity, of hyaluronan. Most importantly, they worked from the very beginning in close cooperation with ophthalmic surgeons, who expressed a need for such products to be used for replacement of the vitreous after retinal surgery and protection of the corneal endo-thelium during keratoplasty (corneal transplantation). In 1976, Biotrics, the developer of the noninflammatory fraction of hyaluronan, licensed the manufacturing and marketing rights worldwide (under the trade name Healon) to the Swedish drug company, Pharmacia AB (Uppsala) (9).

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