Psychophysical Studies of Visual Dysfunction in Glaucoma: Lessons Learned and Questions Raised

Abstract

The study of visual dysfunction in ophthalmic disease is important for both elucidating the pathophysiological basis of visual loss and improving patient care. The application of psychophysical procedures in contemporary glaucoma research illustrates this point. Although achromatic automated perimetry (ie differential luminance thresholds) remains the ‘gold standard’ for the clinical diagnosis of glaucomatous optic neuropathy, psychophysical studies of other visual functions (motion discrimination, blue - yellow perimetry, temporal resolution, and contrast sensitivity) have led to the development of a more comprehensive framework for investigating the mechanisms underlying glaucoma-induced visual impairment. For example, psychophysical studies of the mechanisms mediating visual dysfunction in glaucoma suggest that neurodegenerative changes reduce redundancy in the neural circuitry in a manner that may be selective for, but possibly not specific to, particular neural pathways. In addition, psychophysical studies have significantly advanced our understanding of the nature and scope of visual deterioration in this disease. As a direct result of these studies new clinical tools have been designed which (1) increase sensitivity for detecting early signs of visual impairment, (2) more accurately predict which glaucoma suspects will develop the disease, and (3) provide a more precise metric for both monitoring disease progression and evaluating treatment efficacy (eg in clinical trials). In this presentation I describe the status of our knowledge of visual impairment in glaucoma and highlight the contributions of visual psychophysics to the evolution of this understanding.