CROSS-LINKING OF VITREOUS COLLAGEN AND DEGRADATION OF HYALURONIC-ACIDINDUCED BY BILIRUBIN-SENSITIZED PHOTOCHEMICAL-REACTION

To determine the mechanisms of vitreous liquefaction following vitreou s hemorrhage, we investigated the effects of the free radicals produce d by a bilirubin-sensitized photochemical reaction on collagen and hya luronic acid (HA). Bovine vitreous collagen and HA were irradiated by visible light in the presence of bilirubin, which is produced from the degradation of hemoglobin, as a photosensitizer. Changes in molecular weight were monitored by sodium dodecyl sulfate-polyacrylamide gel el ectrophoresis for the collage, and high-performance liquid chromatogra phy for the HA. We found that free radicals caused an increase in high -molecular-weight components and insolubilization of the vitreous coll agen, and a decrease in the molecular weight of HA. The changed molecu lar properties of the vitreous collagen could be attributed to the ext ensive cross-linking of the molecules. This cross-linking and the degr adation of HA, both induced by the bilirubin-sensitized photochemical reaction, may contribute to vitreous liquefaction following vitreous h emorrhage. (C) 1997 Japanese Ophthalmological Society.