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

Abstract

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 6 SD, 171.88 6 3.58) was significantly larger than that of the structural DFR angle (166.58 6 3.28) in 14 eyes with upper hemifield defects and vice versa in 11 eyes with lower hemifield defects (163.48 6 3.08 vs. 170.58 6 3.28). 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.

Ability of Macular Inner Retinal Layer Thickness Asymmetry Evaluated by Optical Coherence Tomography to Detect Preperimetric Glaucoma

“…A recent report 21 showed that the horizontal raphe in the temporal macular area was different from the fovea-disc line. Another study 22 reported that the structural temporal raphe was more deviated to the perimetrically normal hemiretinal side than to the functional temporal raphe in eyes with a glaucomatous hemifield defect. A third limitation is that there were only five patients in which we captured OCT data prior to the appearance of glaucomatous changes to the fundus which could be used to demonstrate that the appearance of asymmetry in retinal thickness revealed by OCT is an initial sign of glaucoma onset.…”

Geometry of the Retinal Nerve Fibers From Emmetropia Through to High Myopia at Both the Temporal Raphe and Optic Nerve

“…Mean subject age was 25 years (range, [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] and spherical equivalent (SE) ranged from 0D to À13D (minimum 10 subjects per 1D range of refraction between 0D to À5D; 27 subjects in the range À3 to À6D; 17 subjects beyond À6D). Axial length and vitreous chamber depth (VCD) were measured by A-scan ultrasonography (AL-100 biometer; Tomey GmbH, Nürnberg, Germany).…”

“…18 Hence, the anatomy of the temporal raphe may be relevant to improving the assessment of glaucoma. 11,13,14,[18][19][20][21][22] Furthermore, the low density of RNFL bundles in this area may enable direct visualization of changes to bundle density. Glaucomatous deficits occur characteristically in this region, which corresponds to the nasal step of the visual field.…”

“…Previous studies using higher resolution imaging of the raphe have included few participants (e.g., N ¼ 15 to 25) 12,22,24 or have not employed a range of refractive errors, 21 thereby making it unclear whether axial elongation of the eye is an important determinant of the geometry of retinal nerve fiber bundles at the raphe. However, there is good reason to investigate this issue, given differences in fiber distribution at the disc as previously noted in myopia.…”