Initial arcuate defects within the central 10 degrees in glaucoma

Abstract

Purpose: To better understand the relationship between the spatial patterns of functional (visual field [VF] loss) and structural (axon loss) abnormalities in patients with glaucomatous arcuate defects largely confined to the central 10° on achromatic perimetry.

Methods: Eleven eyes (9 patients) with arcuate glaucomatous VF defects largely confined to the macula were selected from a larger group of patients with both 10-2 and 24-2 VF tests. Eyes were included if their 10-2 VF had an arcuate defect and if the 24-2 test was normal outside the central 10° (i.e., did not have a cluster of three contiguous points within a hemifield). For the structural analysis, plots of retinal nerve fiber layer (RNFL) thickness of the macula were obtained with frequency-domain optical coherence tomography (fdOCT). The optic disc locations of the RNFL defects were identified on peripapillary fdOCT scans.

Results: The VF arcuate defects extended to within 1° of fixation on the 10-2 test and were present in the superior hemifield in 10 of the 11 eyes. The arcuate RNFL damage, seen in the macular fdOCT scans of all 11 eyes, involved the temporal and inferior temporal portions of the disc on the peripapillary scans.

Conclusions: Glaucomatous arcuate defects of the macula's RNFL meet the disc temporal to the peak of the main arcuate bundles and produce a range of macular VF defects from clear arcuate scotomas to a papillofoveal horizontal step ("pistol barrel scotoma"). If RGC displacement is taken into consideration, the RNFL and VF defects can be compared directly.

Figure 1.

The 24-2 test pattern showing the region (dashed diagonal lines) represented by the 10-2 test pattern. Patients were excluded if their 24-2 had a significant cluster (5%, 5%, or 1%) of points outside this region, but within a hemifield.

Figure 2.

(A–H) The results of eight eyes with complete arcuate defects on the 10-2 test. For each panel, the columns show the results for the 10-2 test (left) and fdOCT RNFL thickness analysis (right). For the RNFL thickness plot, the code is shown as the color bar in Figure 3D.

Figure 3.

(A–C) Same as in Figure 2 for 3 patients with partial arcuates on the 10-2 test. For the RNFL thickness plot, the code is shown as the color bar in (D).

Figure 4.

(A) RNFL profile (black curves) from fdOCT optic disc volume scan for the right eye of patient 6. The colored regions code the confidence intervals from control values. The arrow shows the dip in the RNFL profile associated with the VF defect. (B) The pseudocolor RNFL thickness plot for the same eye superimposed on the patient's fundus photograph. Blue circle: the locus of points represented in (A). Red dot: the location of the dip in (A). For the RNFL thickness plot, the code is shown as the color bar in Figure 3D.

Figure 5.

Median total deviation for the 10-2 tests of the eight patients in Figure 2 with superior field arcuate scotomas.

Figure 6.

(A) The locations of the test spots on the 10-2 (open symbols, left) are shown on a schematic representation of the fundus view of the retina (small open symbols, right). The filled symbols, left show the location of the associated RGCs after taking the displacement of these cells into consideration. (B) Same as in (A) with the borders shown for the defect seen on the median plot in Figure 6. (C) Same as in (B) but for the cecocentral defect seen in patient 9 (Fig. 3C).

Figure 7.

(A) The schematic representation from Figure 6A is superimposed on the fundus photo and RNFL thickness maps of patient 6 (Fig. 2F). The region within the red borders is the portion of the RNFL that is predicted to be abnormal based on the VF in (B). (B) The 10-2 VF of this patient with the abnormal points outlined in red.