Optovue’s AngioAnalytics software is a gateway to previously unobtainable information.

The AngioVue optical coherence tomography angiography (OCTA) system by Optovue allows for noninvasive visualization of vascular structures of the retina and choroid in normal subjects, glaucoma patients, and patients with retinal diseases. With the US Food and Drug Administration’s (FDA) approval of AngioAnalytics software in June 2018, clinicians can now quantitatively assess the retinal vasculature and any changes over time.

AngioVue OCTA is the first FDA-cleared device that quantifies vessel density of the retinal vasculature, including the radial parapapillary capillaries (RPC), along with retinal structural analyses. “The AngioAnalytics software aids clinicians in distinguishing disease cases from normal cases and stable cases from those that are progressing,” says Qienyuan Zhou, PhD, vice president of clinical affairs for Optovue, Inc.

“Both the noninvasive vascular imaging with OCTA and the ability to quantify the density of the RPC around the optic disc and the superficial vascular complex in the macula provide clinicians with information that was not available previously in glaucoma management,” Dr. Zhou says. “It also creates opportunities to correlate vasculature findings to structural findings and visual-field findings. Furthermore, OCTA scans, with high sampling density, better signaling, and 3D-motion correction, facilitate clear visualization of fine retinal structural features and reliable and reproducible quantitative analysis.”

Robert N. Weinreb, MD, director of the Shiley Eye Institute and distinguished professor and chair of ophthalmology at the University of California, San Diego, has used OCTA for more than 3 years in research at the Hamilton Glaucoma Center at University of California. “For glaucoma, the peripapillary region and macula — areas of keen interest for diagnosing and monitoring glaucoma — can be reproducibly assessed by quantifying the radial peripapillary capillaries and superficial macula vessels,” he says.

Clinical Applications

AngioAnalytics software provides quantitative tools to assess retinal vasculature and retinal structures simultaneously from an OCTA scan. The software provides measurements of vessel density for the macular and peripapillary regions and fovea avascular zone, along with thickness of retinal layers, the retinal nerve fiber layer (RNFL), and optic disc parameters. Change analysis is also provided for these measurements.

Vascular information is helpful in assessing glaucoma patients, especially because it is available alongside OCT structural information without requiring a separate scan. “For cases where structural findings and visual-field findings are not in agreement, vasculature information provides additional information that can help interpret results,” Dr. Zhou says. “For advanced glaucoma patients in which structural analysis may be near its measurement floor, vessel density analysis may still provide information to complement visual field assessment.”

Dr. Weinreb and colleagues have reported that AngioAnalytics software can detect glaucoma progression in some patients even earlier than standard OCT RNFL measures.¹ “It’s also useful in patients with advanced disease,” he says.

The software can also be used to assess treatment response. While RNFL tissue loss is irreversible, the impairment of microvasculature perfusion may be modifiable through treatment, Dr. Zhou speculates. Further clinical research is needed to determine if this is indeed the case. The software’s quantitative analysis of vasculature and retinal structure is repeatable and reproducible across AngioVue instruments, based on clinical trial data (ClinicalTrials.gov identifier: NCT02911883).

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The AngioAnalytics QuickVue report provides vessel density analysis and structural analysis (ie, RNFL or ganglion cell complex [GCC] thickness) with perfectly aligned analysis regions along with disc morphology analysis on one screen.

The Optovue-exclusive focal loss volume (FLV) parameter measures the focal loss over the entire GCC map. This analysis allows for the detection of defects in the GCC, which is the most predictive factor for glaucoma progression in suspected glaucoma cases and in diagnosed patients.²

The software can also measure areas of flow in the retina by outlining a region for vessel detection. The extracted flow area measurement is based on the outer retina slab. Other measurements include foveal avascular zone (FAZ) area, perimeter and foveal vessel density, as well as other nonflow areas within the superficial plexus of the retina.

Improving Outcomes

Dr. Zhou believes that AngioAnalytics software can potentially aid in achieving a more accurate diagnosis and potentially contribute to better monitoring of glaucoma progression and treatment response.

“One hypothesis is that vessel density change is an earlier biomarker for glaucoma progression than standard OCT measures,” Dr. Weinreb says. This hypothesis will need to be tested in longitudinal studies. GP

References

1. Shoji T, Zangwill LM, Akagi T, et al. Progressive macula vessel density loss in primary open-angle glaucoma: a longitudinal study. Am J Ophthalmol. 2017;182:107-117.
2. Zhang X, Loewen N, Tan O, et al; Advanced Imaging for Glaucoma Study Group. Predicting development of glaucomatous visual field conversion using baseline fourier-domain optical coherence tomography. Am J Ophthalmol. 2016;163:29-37.