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. 2018 Aug 7;13(8):e0201729.
doi: 10.1371/journal.pone.0201729. eCollection 2018.

Optic Disc Microvasculature Dropout in Primary Open-Angle Glaucoma Measured With Optical Coherence Tomography Angiography

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Free PMC article

Optic Disc Microvasculature Dropout in Primary Open-Angle Glaucoma Measured With Optical Coherence Tomography Angiography

Tadamichi Akagi et al. PLoS One. .
Free PMC article

Abstract

Purpose: To evaluate microvasculature dropout in the optic disc (Mvd-D) using optical coherence tomography angiography (OCTA) and investigate factors associated with Mvd-D in primary open-angle glaucoma (POAG) eyes.

Methods: One hundred twenty-three eyes of 123 POAG patients were included from the Diagnostic Innovations in Glaucoma Study. The 3.0×3.0-mm optic nerve head OCTA scans were acquired using a spectral-domain OCT instrument. Images with whole-signal-mode were evaluated. Eyes were classified into 3 categories (Mvd-D, pseudo-Mvd-D, and no Mvd-D). Mvd-D and pseudo-Mvd-D had complete loss of OCTA signals on the temporal side of the optic disc on the en face projection image. They were distinguished base on the visualization of the anterior lamina cribrosa in the horizontal B-scans of that area. No Mvd-D was defined when no complete signal loss of OCTA signals was observed. Covariates including focal lamina cribrosa defects assessed by swept-source OCT and microvasculature dropout in the parapapillary region (Mvd-P) were analyzed.

Results: Forty-two, 37, and 44 eyes were identified as having Mvd-D, pseudo-Mvd-D, and no Mvd-D, respectively. The eyes with Mvd-D showed significantly lower intraocular pressure, worse visual field mean deviation, larger cup-to-disc ratio, thinner circumpapillary retinal nerve fiber layer (cpRNFL), and lower circumpapillary vessel density within the RNFL than the eyes with pseudo-Mvd-D or the eyes without Mvd-D. Multivariable logistic regression analysis showed significant associations of Mvd-D with larger cup-to-disc ratio (OR, 1.08; P = 0.001), worse visual field mean deviation (OR, 1.09; P = 0.048), higher prevalence of focal lamina cribrosa defect (OR, 9.05; P = 0.002), and higher prevalence of Mvd-P (OR, 10.33; P <0.001).

Conclusions: OCTA-derived Mvd-D was strongly associated with the presences of Mvd-P and focal lamina cribrosa defects, and these 3 findings were topographically associated with each other.

Conflict of interest statement

This study was funded by National Eye Institute grants: EY029058 (RNW), EY011088 (LMZ), EY014267 (LMZ), EY019689 (LMZ), Core Grant P30EY022589 (LMZ); an unrestricted grant from Research to Prevent Blindness (RNW), grants for participants’ glaucoma medications from Alcon, Allergan, Pfizer, Merck and Santen (RNW) and the John Mung Program from Kyoto University Global Frontier Project for Young Professionals (TA). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript. This does not alter our adherence to PLOS ONE policies on sharing data and materials.

Figures

Fig 1
Fig 1. Optical coherence tomography angiography (OCTA) microvasculature images of optic nerve head in glaucoma eye without microvasculature dropout inside the optic disc.
OCTA en face projection images in the retinal nerve fiber layer (RNFL) (Top left), superficial layer (Top right), and the whole-depth (Second row). The red ellipse indicates the optic disc boundary and red lines show the boundaries of evaluation areas. Superotemporal and inferotemporal regions were used for evaluation of microvasculature dropout. The yellow and green lines indicate the location of the B-scans in the bottom row. Bottom, Cross-sectional angiogram images overlying the B-scan images. Microvasculature in the anterior portion of lamina cribrosa is visualized in the area shown by orange arrowheads, while the anterior lamina cribrosa and microvasculature cannot be detected because of vessel shadowing in the area shown by aqua arrowheads. Yellow and aqua borders show the inner limiting membrane (ILM) and 80 μm below the ILM, respectively.
Fig 2
Fig 2. Flowchart determining the classification based on microvasculature dropout inside the optic disc (Mvd-D).
Fig 3
Fig 3. Examples of eyes with microvasculature dropout (Mvd) inside the optic disc (Mvd-D), pseudo-Mvd-D, and no Mvd-D.
A, The Mvd-D and Mvd in the parapapillary region (Mvd-P) are enclosed by yellow and aqua border, respectively. A3, Anterior lamina cribrosa (LC) surface is well visualized as shown by yellow dotted line. Yellow arrows indicate the borders of the Mvd-D. It should be noted that the area between 2 yellow arrows does not contain any microvasculature signal in the prelaminar tissue and anterior portion of LC. B,C, Pseudo-Mvd-Ds are shown by yellow dotted border. Anterior LC could not be observed between 2 yellow arrows, which indicate the borders of the pseudo-Mvd-D, because of shadowing by neuroretinal rim (B3) and large retinal vessel (B4, C3). D, No Mvd-D is observed in the temporal side of the optic disc. Optic disc border is shown by red ellipse and the border for evaluation is shown by red lines (A2―D2).
Fig 4
Fig 4. Representative cases of eyes with microvasculature dropout (Mvd) inside the optic disc (Mvd-D).
A―G, Left eye of a 74-year-old man with primary open-angle glaucoma (POAG). A, Neuroretinal rim thinning is observed at the temporal area of the optic disc. B, Humphrey Visual Field Analyzer with the 24–2 Swedish interactive threshold algorithm standard (HFA24-2) grayscale image showing severe visual field defects (visual field mean deviation [MD], -16.91 dB). C, Optical coherence tomography (OCT) angiography (OCTA) en face projection image with whole-signal-mode. Red ellipse indicates optic disc border. Yellow and aqua borders indicate Mvd-D and Mvd in the parapapillary area (Mvd-P), respectively. D, E, B-scan OCT images and cross-sectional angiogram images overlying the B-scan image acquired at the yellow (D) and green line (E) in C2. Microvasculature is observed in the prelaminar tissue and anterior lamina cribrosa (LC) in D, while no microvasculature is seen in the Mvd area of E. Yellow arrows indicate the borders of Mvd-D. Yellow dotted lines show anterior LC surface. Red arrow indicates focal LC defect. F, G, En face (F) and horizontal section of volume scan (G) of swept-source OCT images. Red dotted line indicates anterior LC surface, and red arrow shows focal LC defect. H―N, Right eye of a 62-year-old woman with POAG. H, Inferotemporal rim thinning is observed. I, HFA24-2 grayscale image showing mild visual field defects (visual field MD, -1.72 dB). J, OCTA en face projection image with whole-signal-mode. Red ellipse indicates optic disc border. Yellow and aqua borders indicate Mvd-D and Mvd-P, respectively. K, L, B-scan OCT images and cross-sectional angiogram images overlying the B-scan image acquired at the yellow (K) and green line (L) in J2. Microvasculature is observed in prelaminar tissue and anterior LC in K, while no microvasculature is seen in the Mvd area of L. Yellow and aqua arrows indicate the borders of Mvd-D and Mvd-P, respectively. Yellow dotted lines show anterior LC surface, and red arrow indicates focal LC defect. M, N, En face (M) and horizontal section of volume scan (N) of swept-source OCT images. Red dotted line indicates anterior LC surface, and red arrow shows focal LC defect.

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