Discordance of Disc-Fovea Raphe Angles Determined by Optical Coherence Tomography and MP-3 Microperimetry in Eyes With a Glaucomatous Hemifield Defect

PURPOSE. The purpose of this study was to evaluate the concordance of a temporal raphe architecture estimated using optical coherence tomography (OCT) and MP-3 microperimetry. METHODS. We enrolled 25 eyes with either an upper or lower glaucomatous hemifield defect, as detected on the Humphrey visual field 30-2 test. A structural temporal raphe was extrapolated from visible end points of retinal nerve fiber bundles present in a perimetrically normal hemiretina on an en face Spectralis OCT image. A functional temporal raphe was drawn as a line from the fovea to the border of at least a 10-dB difference in sensitivity, at vertically adjacent test points, with at least three consecutive pairs among 25 test points placed at 88 to 188 from the fovea (28 intervals) on the MP-3. An angle determined by the optic disc center, the fovea, and the temporal raphe line (the DFR angle) was calculated. Correlations and agreement of the OCT- and MP-3-derived DFR angles and factors affecting discordance of the two estimates were evaluated. RESULTS. Despite no significant demographic differences, the functional DFR angle (mean +/- SD, 171.8 degrees +/- 3.5 degrees) was significantly larger than that of the structural DFR angle (166.5 degrees +/- 3.2 degrees) in 14 eyes with upper hemifield defects and vice versa in 11 eyes with lower hemifield defects (163.4 degrees +/- 3.0 degrees vs. 170.5 degrees +/- 3.2 degrees). The mean deviation was significantly associated with the functional and structural DFR angle difference in eyes with only upper hemifield defects. CONCLUSIONS. The structural temporal raphe was more deviated to the perimetrically normal hemiretina side than to the functional temporal raphe, thereby suggesting that a structural change may precede a functional loss.