REGIONAL NMR MULTINUCLEAR STUDIES OF OCULAR TISSUES

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The principal objective of this application is to apply novel magnetic resonance imaging techniques to the examination of water transport by the cornea and the lens in vivo. The specific aims are: (1) analyze corneal water transport under anaerobic stress using a T2 contrast agent H217O; and (2) image water self- diffusion, free- and bound-water interchange, and waterbulk-flow in metabolically stressed lenses. We will use rabbits as the experimental animal. The experimental models include acute galactosemic cataract and corneal oxygen deprivation. The effects on water transport of pericorneal factors such as lacrimation, limbal circulation and aqueous flow are tested by pharmaceutically altering these factors. These are simple yet effective models that can be used to develop advanced ocular MRI techniques. The proposed studies are essential to the establishment of MRI-based functional assessment of anterior segment diseases and their therapies. The results will provide useful information on (1) normal and pathological corneal interaction with water - important in the evaluation of, for example, dry eyes, wound-healing and contact lens wear; and (2) water movement in different regions of the lens during metabolic cataractogenesis - important in the further understanding of the biophysical changes during cataract formation and testing of the efficacy of anti-cataract therapy.