Effects of the Relative Positioning between the Disc-Fovea Angle and Localized Optic Disc Defects on the 10-2 Visual Field Results in Glaucoma

Abstract

Purpose: To investigate the effects of the foveal position relative to the optic disc on the 10-2 visual field (VF) results of glaucoma patients with localized inferotemporal neuroretinal rim defects (ITD). Design: Cross-sectional study. Participants: Fifty-seven eyes of 35 open-angle glaucoma (OAG) patients were included and divided into two groups based upon the presence (18 eyes) or not (39 eyes) of ITD. Methods: Three different parameters obtained from a spectral domain optic coherence tomography (sdOCT) [disc-fovea angle (DFA), fovea vertical deviation (FVD) from midline, and the angular difference between the ITD border and the DFA (DAD)] were tested for their relationship with four 10-2 VF sectors: superior hemifield, superior edge, nasal edge, and superonasal arcuate. These relationships were tested with regression analyses with linear mixed effects models and random intercepts. Main Outcome Measures: Influences of DFA, FVD, and DAD on 10-2 VF sectors. Results: Mean (±SD) values of DFA, FVD, and DAD were respectively: −5.05° ± 4.40°, −1346.6 um ± 1609.0 um, and 43.30° ± 17.33°. After adjustment for multiple comparisons, both FVD and DAD, but not DFA, were significantly associated with the severity of defects on the predefined VF sectors. Larger DAD values (third tertile: 54°-77°) showed higher coefficient estimate for the nasal edge sector sensitivities. Conclusions: The vertical foveal location and its position relative to the ITD was associated with loss of sensitivity at 10-2 VF locations in the superior hemifield. This association was significant but weak and was not seen using other conventional parameters that describe foveal position relative to the optic disc on sdOCT.

Anatomic and refractional correlations in earliest glaucomatous visual field defects

“…We justify this difference by the small number of patients in the study, a different number of participants between the groups (20 eyes in the myopic Group vs. 32 eyes in the hyperopic Group), and all patients having negative DFA. Matos et al did not report an association of the central defect with DFA but with the vertical deviation of the fovea (10) . One of the main limitations of this study was the possibility of inclination and rotation of the optic nerve.…”

“…We performed DFA measurements in a masked way and with good agreement between measurements, although the measurements were examiner-dependent. The sample size calculation was based on previous studies (10,14,15) , and the low number of participants can also be a limitation of the study.…”

“…The sample size calculation was based on the SD of the DFA measurements from previous studies (10,14,15) . Considering an α value of 0.05 and a study power of 90%, at least 20 eyes per group should have been analyzed.…”

“…Also, systemic and refractive anatomical variations, mostly of the posterior pole, directly influence the initial location of the visual field defect (8) . The anatomical position of the fovea and its relationship between distance and angulation to the optic nerve can affect macular RNFL distribution (9) and the disk-fovea angle (DFA) (10,11) , as the axial length (LA) promotes increased risk of central visual field lesions (12) .…”