Correlation of Visual Field With Peripapillary Vessel Density Through Optical Coherence Tomography Angiography in Normal-Tension Glaucoma

Abstract

Purpose: To investigate the retinal vessel density (VD) in healthy and normal-tension glaucoma (NTG) eyes through optical coherence tomography angiography (OCTA) and to determine the correlation between VD and the retinal nerve fiber layer (RNFL) thickness and functional visual field (VF) defects for different locations.

Methods: A total of 74 NTG eyes and 24 healthy eyes were included. OCTA VD at 4.5 × 4.5 mm peripapillary region and 3.0 × 3.0 mm macula area, RNFL thickness, and VF pattern deviation results were individually analyzed on the basis of the Garway-Heath sectorization. Correlations between VD and VF/RNFL and VF were compared.

Results: In the NTG group, peripapillary VD, superficial macula VD, RNFL thickness, and ganglion cell complex thickness were significantly lower. In the whole peripapillary area and inferotemporal sector, anatomic correlations between VD and VF pattern deviation values were significantly higher than those between the RNFL thickness and VF values. In the subgroup analysis, VD was anatomically correlated with VF in early-, moderate-, and severe-stage NTG eyes, whereas the RNFL thickness was correlated with VF in moderate- and severe-stage NTG eyes.

Conclusions: We observed VD reduction in the peripapillary retina and superficial macula area in NTG eyes. The microvascular dropout of VD in the peripapillary retina, especially in the inferotemporal sector, provided a more accurate anatomic correlation with functional VF defects than that of the RNFL thickness, especially in early-stage NTG eyes.

Translational relevance: In patients who cannot comply VF exam, VD is a good tool for disease detection.

Keywords: Normal-tension glaucoma; Optical coherence tomography angiography; Vessel density; Visual field defect.

Figure 1.

Representative case of a normal-tension glaucoma eye. (a) The color photograph shows rim thinning at superotemporal and inferotemporal regions. (b) The 30–2 Swedish interactive threshold algorithm standard pattern deviation image obtained using the Humphrey visual field analyzer shows superior and inferior visual field defects with central involvement (visual field mean deviation: −8.94 dB). Scores in the pattern deviation map are grouped according to the Garway-Heath map. (c) The circumpapillary RNFL thickness map shows thinning at superior-temporal and inferior-temporal regions. (d) The OCTA vessel density image shows apparent microvascular reduction at inferior and superior regions inside and around the optic disc. (e) The superficial layer of the retina was measured in the 3.0 × 3.0 mm region centered on the fovea. The boundary of the superficial retinal layer extends from the internal limiting membrane to the inner plexiform layer. (f) The deep retinal layer measured in the 3.0 × 3.0 mm region centered on the fovea. The boundary of the deep retinal layer extends from inner to outer plexiform layers. (g) The GCC thickness map covering a 7.0 mm region shows thinning at the inferior area.

Figure 2.

Scatterplot between vessel density (VD) and VF pattern deviation values in the whole peripapillary area (a); between RNFL thickness and VF pattern deviation values in the whole peripapillary area (b); between VD and VF pattern deviation values in the inferotemporal sector (c); between RNFL thickness and VF pattern deviation values in the inferotemporal sector (d). The value of VD and RNFL thickness after taking log was used in the scatterplot.