Three-dimensional structure-function relationships in glaucoma from SD-OCT

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DESCRIPTION (provided by applicant): This Phase-II proposal seeks to elucidate the structure-function relationships between visual field threshold sensitivity and the structural features of the retinal layers, the optic nerve head, and the connecting nerve fiber bundles in glaucoma. This proposal extends our successful Phase-I research that established structure- structure relationships among retinal quantitative indices. In this Phase II, further advancements of spectral domain optical coherence tomography (SD OCT) image analysis will yield new damage metrics expected to correspond much better with visual field threshold sensitivity. The project is driven by an important clinical problem - the poor reliability and reproducibility of th visual field as a measure of irreversible damage to the retinal ganglion cells and their axons in glaucoma. Our long-term vision remains to determine/predict glaucoma visual function from objective structure measurements by OCT. Once achieved, this new approach will provide an objective and reproducible measure, complementing subjective functional assessment of glaucoma damage, decrease the need for frequent visual field testing resulting from long-term fluctuation of visual response, and improve glaucoma treatment based on reliable progression markers. Specifically, we will develop predictive models of increasing complexity yielding a patient- specific predictive model of glaucomatous damage. The overriding hypothesis motivating the proposed research is that novel quantitative metrics of the entire retinal ganglion cell-axonal complex morphology utilizing the nerve fiber bundle trajectories allow reliable prediction of visual function. We have identified the following specific aims: Aim 1: Establish a baseline for the focal structural-functional correlation in the retina covered by the Humphrey 24-2 perimetry test (24 degree radius visual field) by comparing 24-2 thresholds with their corresponding structural indices derived from registered multi-field SD-OCT scans in glaucoma and normal subjects. Derive a baseline predictive model of function from structural properties of the inner retinal layers, comprised of retinal ganglion cell and nerve fiber layers. Aim 2: Demonstrate that incorporating structural parameters along SD-OCT atlas-based retinal ganglion cell- axonal complex (RGC-AC) trajectories improves the performance of the predictive structure-function model. Aim 3: Evaluate whether prediction of 24-2 thresholds is improved by deriving individual-based RGC-AC trajectories instead of from an RGC-AC atlas. The proposed work will be performed using 7-field per eye 3D SD-OCT images accompanied by 24-2 visual field test data on the same day from 100 patients with glaucoma and 40 age-matched normal subjects.