CYTOTOXICITY OF VISCOELASTICS ON CULTURED CORNEAL EPITHELIAL-CELLS MEASURED BY PLASMINOGEN-ACTIVATOR RELEASE

BACKGROUND: Plasminogen activator has been shown to be released by epi thelial cells following corneal injury. The demonstration of the relea se of plasminogen activator from cultured corneal epithelial cells has been used for developing a cytotoxicity test, the Corneal Epithelial Plasminogen Activator test, which compares changes in the level of pla sminogen activator in tissue culture media following chemical exposure as an index of chemical injury. METHODS: Cultured rabbit corneal epit helial cells were exposed to varying concentrations of several viscoel astics for 1 hour. Release of plasminogen activator into the tissue cu lture media following exposure to the viscoelastic agent was studied a s an index of chemical injury. RESULTS: The least cytotoxicity to cult ured rabbit epithelium was associated with those viscoelastic agents c ontaining methylcellulose. A 1-hour exposure to most concentrations of methylcellulose and chondroitin sulfate (Phacote) and methylcellulose (Occucoat) demonstrated release of greater amounts of plasminogen act ivator than was seen following a similar exposure to balanced salt sol ution, suggesting the greatest protective effect of these two viscoela stics. In contrast, sodium hyaluronate and chondroitin sulfate (Viscoa t) showed decreased amounts of plasminogen activator release after a 1 -hour exposure to cultured corneal epithelial cells demonstrating cyto toxicity. Polyacrylamide (Orcolon) and most diluted preparations of so dium hyaluronate (Healon and Healon Yellow) showed only mild reduction s in the release of plasminogen activator, whereas undiluted sodium hy aluronate preparations were nearly as cytotoxic as Viscoat. CONCLUSION S: This study suggests that viscoelastic agents containing methylcellu lose (Phacote and Occucoat) may be most protective of the corneal epit helium during ophthalmic surgery. The clinical success of several dilu te viscoelastic solutions as tear substitutes was corroborated by the lack of cytotoxicity seen in this study. Viscoat and undiluted sodium hyaluronate preparations showed the greatest cytotoxicity to cultured rabbit corneal epithelium.