BACKGROUND: Imaging is widely used to quantify glaucomatous structural changes. Although previous studies have examined the relationship between structure and function, measured using standard automated perimetry (SAP), the true relevance of structural changes remains poorly understood. AIM: The aim of this body of work was to explore the structure-function relationship and to ascertain the point at which structural changes become associated with impaired ability to perform vision-dependent tasks. PLAN OF RESEARCH: After critically appraising previously described structurefunction models, an investigation was conducted progressively evaluating the relationship between glaucomatous structural changes and 1) estimated loss of retinal ganglion cells (RGCs), 2) an objective measure of visual function (the pupil response), and 3) a vision-related task relevant to quality of life (driving). RESULTS: Localised RNFL defects visible on photographs, a common manifestation of glaucoma, were associated with large estimated RGC losses. However, problems were identified with the published method of RGC estimation. Asymmetric RNFL thinning was also found to be associated with asymmetry of the pupil response, and the magnitude of asymmetry required for a clinically detectable relative afferent pupillary defect (RAPD) was calculated. Finally, loss of RNFL was associated with worse ability to perform a simulated driving task, providing additional information to SAP alone. SIGNIFICANCE: Glaucomatous structural defects may be associated with significant functional impairment. Incorporating information from both structure and function may improve our ability to predict patients at risk of developing problems with vision-related tasks of daily living
