[Relationship between the nerve fiber layer defect and parafoveal visual field defects in glaucomatous eyes]

We evaluated the nerve fiber layer defect (NFLD) in glaucomatous eyes imaged by a scanning laser ophthalmoscope (SLO, Rodenstock Gm BH, Munich, Germany) and its relationship to parafoveal visual field defects. Twenty-three eyes of 20 patients with open angle glaucoma were studied. Only those eyes were used in which NFLD reaching the temporal raphe of the nerve fiber layer was observed by the SLO in either the superior or the inferior hemisphere. We defined three topographic parameters of the NFLD: 1. the angle (0, degree) generated by a line A passing through the foveal pit and the disc center, and a line through the disc center to the point of the NFLD at the disc edge and closest to line A, 2. the horizontal distance (D1, mm) along the temporal raphe between the foveal pit and the point of the NFLD nearest to the foveal pit, and 3. the vertical distance (D2, mm) between the foveal pit and the point of NFLD nearest to the foveal pit. We also defined the nearest defect location (in degrees from the fovea) as the stimulus point with sensitivity loss greater than 6 dB in the Humphrey visual field (program central 10-2). A highly significant correlation was observed between each of the three NFLD parameters and the nearest defect location (p < 0.001). The NFLD parameters we have newly defined here may be helpful for evaluating parafoveal visual functional damages in open angle glaucoma.