Relationship between Optical Coherence Tomography Angiography Vessel Density and Severity of Visual Field Loss in Glaucoma

Abstract

Purpose To evaluate the association between vessel density measurements using optical coherence tomography angiography (OCT-A) and severity of visual field loss in primary open-angle glaucoma (POAG) Design Observational cross-sectional study Participants One hundred and fifty three eyes from 31 healthy, 48 glaucoma suspects, and 74 glaucoma participants enrolled in the Diagnostic Innovations in Glaucoma Study Methods All eyes underwent imaging using an OCT-A (Angiovue, Optovue; Fremont, CA) and a spectral domain OCT (Avanti, Optovue; Fremont, CA), along with standard automated perimetry (SAP). Retinal vasculature information was summarized as vessel density, the percent of area occupied by flowing blood vessels in the selected region. Two measurements from the retinal nerve fiber layer (RNFL) were utilized: circumpapillary vessel density (cpVD) (750-μm-wide elliptical annulus around the optic disc); and whole image vessel density (wiVD) (entire 4.5 × 4.5 mm scan field) Main Outcome Measures Associations between severity of visual field loss, reported as SAP mean deviation (MD) and OCT-A vessel density Results Compared to POAG eyes, normal eyes demonstrated a denser microvascular network within the RNFL. Vessel density was higher in normal eyes followed by glaucoma suspects, mild glaucoma and moderate to severe glaucoma eyes for wiVD (55.5, 51.3, 48.3, 41.7% respectively) and for cpVD (62.8, 61.0, 57.5, 49.6% respectively) (P<0.001 for both). The association between the severity of visual field damage (MD) with cpVD and wiVD was stronger (R2=0.54, and R2=0.51 respectively) than the association between visual field MD and RNFL (R2=0.36) and rim area (R2=0.19) (P<0.05 for all). Multivariate regression analysis, adjusted for confounders, showed that each 1% decrease in cpVD was associated with 0.64 dB loss in MD and each 1% decrease in wiVD, was associated with 0.66 dB loss in MD. In addition, the association between vessel density and the severity of visual field damage was found to be significant even after controlling for the effect of structural loss Conclusions Decreased vessel density was significantly associated with severity of visual field damage independent of the structural loss. OCT-A is a promising technology in glaucoma management, potentially enhancing the understanding of vascular role in the pathophysiology of the disease

An Optical Coherence Tomography Angiography Study of the Relationship Between Foveal Avascular Zone Size and Retinal Vessel Density

“…Partial correlation analyses between FAZ parameters and other structural/ functional parameters (cpRNFLT, mGCIPLT, and MS) were also assessed in the overall and subgroups of OAG eyes after controlling for age. 42 For the correlation between FAZ size and visual function, retinal sensitivity was expressed in both linear (1/L) and dB scales. In this study, the absolute value of correlation coefficient below 0.19 was regarded as very weak, 0.2 to 0.39 as weak, 0.4 to 0.59 as moderate, 0.6 to 0.79 as strong, and 0.8 to 1.0 as very strong correlation.…”

“…In this study, we set the cutoff value of OCTA image quality at SSI >48, as used in many previous studies. 23,25,26,36,[39][40][41][42] Venugopal et al recently reported that SSI value had a significant effect on the repeatability of VD measurement by OCTA. 43 The mean SSI values of our cohort were relatively high, being close to 60, and there was no significant difference among groups in terms of SSI values.…”

“…34,35,37,38 Thus, AL-related magnification factor can be corrected by Dt ¼ 3.460*0.01306*(AL À 1.82)*Dm. 34,35,37,38 Poor quality OCTA images were excluded from the analysis, including signal strength index (SSI) < 48 (minimum ¼ 1, maximum ¼ 100) 23,25,26,36,[39][40][41][42] ; poor-clarity images due to severe media opacities; motion artifacts or localized weak signal by vitreous floaters; residual motion artifacts visible as irregular vessel patterns or disc boundary on the en face angiogram; images not centered on the fovea for macular OCTA (fixation error); and segmentation failure.…”

Novel Retinal Imaging Technologies

“…Moreover, vascular density and FAZ area appear to correlate with visual function. Adeleh et al, [8] evaluated the association between vessel density and severity of visual field loss in primary open-angle glaucoma (POAG). They imaged 153 eyes, which contain 31 normal eyes, 48 glaucoma suspects, and 74 glaucoma eyes, by OCTA (Angiovue; Optovue, Fremont, CA).…”

Evaluation of the optic nerve and scleral-choroidal-retinal layer with ultrasound elastography in glaucoma and physiological optic nerve head cupping

“…In time it can produce damage of the retinal nerve fiber layer (RNFL) and optic nerve, with loss of the related visual field [1,2]. A cup/disc (C/D) ratio (ratio of the cup located in the middle of the optic disc to the optic disc itself) higher than 0.4 raises the suspicion of glaucoma.…”