The early structural and functional disturbances of chronic open-angle glaucoma. Robert N. Shaffer lecture.

The earliest psychophysical disturbances in color vision, foveal sensitivity, spatial and temporal contrast sensitivity precede nerve fiber bundle defects of the visual field in glaucoma. Optic nervehead changes such as enlargement of the physiological cup, as well as retinal nerve fiber layer losses, also precede visual field defects. Which of these is the earliest change has not yet been recognized. Evidence for more than one mechanism of damage in glaucoma is also presented.