Peripapillary Retinal Nerve Fiber Layer Vascular Microcirculation in Eyes With Glaucoma and Single-Hemifield Visual Field Loss

Abstract

IMPORTANCE Understanding the differences in vascular microcirculation of the peripapillary retinal nerve fiber layer (RNFL) between the hemispheres in eyes with glaucoma with single-hemifield visual field (VF) defects may provide insight into the pathophysiology of glaucoma.OBJECTIVE To investigate the changes in the microcirculation of the peripapillary RNFL of eyes with glaucoma by using optical microangiography. DESIGN, SETTING, AND PARTICIPANTSEyes with glaucoma and single-hemifield VF defect and normal eyes underwent scanning using an optical microangiography system covering a 6.7 × 6.7-mm 2 area centered at the optic nerve head. The RNFL microcirculation was measured within an annulus region centered at the optic nerve head divided into superior and inferior hemispheres. Blood flux index (the mean flow signal intensity in the vessels) and vessel area density (the percentage of the detected vessels in the annulus) were measured. MAIN OUTCOMES AND MEASURESDifferences in microcirculation between the hemispheres in eyes with glaucoma and normal eyes and correlations among blood flow metrics, VF thresholds, and clinical optical coherence tomography structural measurements were assessed.RESULTS Twenty-one eyes from 21 patients with glaucoma (7 men and 14 women; mean [SD] age, 63.7 [9.9] years) and 20 eyes from 20 healthy control individuals (9 men and 11 women; mean [SD] age, 68.3 [10.7] years) were studied. In eyes with glaucoma, the abnormal hemisphere showed a thinner RNFL (mean [SE] difference, 23.5 [4.5] μm; 95% CI, 15.1-32.0 μm; P < .001), lower RNFL blood flux index (mean [SE] difference, 0.04 [0.01]; 95% CI, 0.02-0.05; P < .001), and less vessel area density (mean [SE] difference, 0.08% [0.02%]; 95% CI, 0.05%-0.10%; P < .001) than did the normal hemisphere. Compared with normal eyes, reduced RNFL microcirculation was found in the normal hemisphere of eyes with glaucoma, measured by mean [SE] differences in blood flux index (0.06 [0.01]; 95% CI, 0.04-0.09; P < .001) and vessel area density (0.04% [0.02%]; 95% CI, 0.02%-0.08%; P = .003) but not in RNFL thickness (3.4 [4.7] μm; 95% CI, −6.2 to 12.9 μm; P = .48). Strong correlations were found between the blood flux index and VF mean deviation (Spearman ρ = 0.44; P = .045) and RNFL thickness (Spearman ρ = 0.65; P = .001) in the normal hemisphere of the eye with glaucoma.CONCLUSIONS AND RELEVANCE Reduced RNFL microcirculation was detected in the normal hemisphere of eyes with glaucoma, with strong correspondence with VF loss and RNFL thinning. Although the results suggest that vascular dysfunction precedes structural changes seen in glaucoma, longitudinal studies would be needed to confirm this finding.

Optical Coherence Tomography Angiography in Glaucoma: A Review

“…Three studies investigated glaucoma eyes with visual field defects in a single hemifield [30, 76, 79]. Interestingly, their findings regarding the perimetrically intact hemiretina could give information about the pathophysiology of glaucoma.…”

“…Interestingly, their findings regarding the perimetrically intact hemiretina could give information about the pathophysiology of glaucoma. The first study found significantly lower OCTA parameters (vessel density and blood flow index) with normal RNFL in the perimetrically intact hemiretina [79]. The second study found a significantly lower RNFL with normal vessel density in the perimetrically intact hemiretina [30].…”

Correlation between Basal Macular Circulation and Following Glaucomatous Damage in Progressed High-Tension and Normal-Tension Glaucoma

“…Concerning the other parameters, RNFL thickness and GCC thickness, which would be influenced by vascular flow [33], were worse in the progressed glaucoma groups of the current study at the last visit. Similar conditions were also found in VF defects, which may correlate with basal vascular impairment compared to HTG with good medical control.…”

“…The main structural parameters of glaucoma include RNFL thickness and GCC thickness, which are influenced by vascular flow [33]. The SmVD in the progressed HTG group is correlated with VF defects, RNFL, and GCC, while both the SmVD and the DmVD in the progressed NTG group were associated with the RNFL and GCC thickness alterations, and the FAZ in the progressed NTG group is correlated with a change in VF defects.…”

The Future of Imaging in Detecting Glaucoma Progression

“…The flow index (mean decorrelation value on the en-face retinogram) and vessel density (area occupied by large vessels and microvasculature), have been shown to be associated with disease severity as reflected by SAP global indices (38). Additional studies demonstrated a reduction in peripapillary vessel density in the hemispheres corresponding to hemifield defects in visual fields (39) (40). In eyes with glaucoma and a single-hemifield defect, diminished vascular density of the macular and peripapillary regions was also demonstrated in unaffected hemifields (41).…”