An improved technique for high-contast, high-resolution fluorescein angiography of the optic disc has been developed that almost eliminates pseudofluorescence. Fluorescein angiography of the optic disc was performed on normal, ocular hypertensive, and glaucomatous patients. Rapid-sequence angiograms in the early arterial phases have demonstrated localized areas of hypofluorescence or filling defects of the optic disc. Two types of fluorescein filling defects were observed-absolute and relative. The number of absolute filling defects, which increased with degree of visual field loss, was greater in glaucomatous than in ocular hypertensive or normal eyes. Similarly, ocular hypertensive eyes showed a larger number of discs with filling defects than normal eyes. It is postulated that relative defects progress to absolute filling defects, which may be an indication of impending loss of visual field.