ROLE OF OXYGEN IN OCULAR PATHOLOGY

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Molecular oxygen can photogenerate four active states of oxygen: singlet oxygen, superoxide anion, hydrogen peroxide, and hydroxyl radical. Although these species have been shown to have damaging effects on proteins, research is particularly limited on their effects on eye tissues such as lens and vitreous. In the present study, changes in chemical properties and conformation by the active species of molecular oxygen of vitreous and lens components (hyaluronic acid and collagen, and lens crystallins, respectively) will be investigated. Spectroscopic methods such as absorption, fluorescence, and circular dichroism will be used for conformational studies. Biochemical and hydrodynamic techniques, including viscosity, gel electrophoresis, light scattering, and sedimentation equilibrium will be used for aggregation and crosslinking studies. To correlate the effect of specific species of oxygen with the change in conformation of the macromolecules, inhibitors or scavengers specific for each species of molecular oxygen will be used. Near-ultraviolet light from sunlight has been implicated in the production of singlet oxygen or other active species of oxygen by photodynamic action of the photosensitizers present in the normal eye. We plan to correlate the physicochemical changes produced by these agents in an in vitro system containing lens or vitreous macromolecular components with cataract or vitreous liquefaction. The long-term objective of this proposal is to define a molecular mechanism for the changes in vitreous and lens components and see if there may be a link between photooxidation and certain eye diseases.