Optical coherence tomography (OCT) angiography, or OCTA imaging, provides wider fields of view at high resolution. “However, while a 3 mm x 3 mm image on OCTA generally has great quality, it often does not encompass the entire extent of the pathology,” says Nadia Waheed, MD, MPH, vitreoretinal specialist and associate professor at Tufts Medical Center in Boston, Massachusetts.
But Optovue’s new AngioVueHD can capture wider images. Jay Wei, founder and CEO, Optovue, Fremont, California, explains that the improved resolution of AngioVueHD’s technology allows physicians to have the image quality they are used to seeing in a smaller imaging format (3 mm x 3 mm) in a larger field of view. “This enables them to eliminate doing 2 scans — one 3 mm x 3 mm scan for the best image quality and one 6 mm x 6 mm scan for a wide field of view,” Wei said. He added that physicians can now have both high-resolution imaging and a wide view in one scan.
“In fact, Optovue currently offers the widest field of view and the highest density scanning of any commercially available OCT system,” said Wei, adding that by eliminating the need for both a 3 mm x 3 mm and a 6 mm x 6 mm scan, AngioVueHD reduces exam times.
The AngioVueHD Montage feature further extends this wide field capability by automatically combining 2 high-density 6 mm x 6 mm scans — the macula and the optic disk — to provide the highest resolution imaging available in a 10 mm x 6 mm imaging format.
A CLOSER LOOK
Optovue’s AngioVueHD increases sample density from 304x304 A scans to 400x400 A scans, which is 73% more than available previously. “This results in a 33% increase in resolution, so that physicians can see even small capillaries clearly,” Wei says. To compensate for artifact caused by eye motion during scanning, DualTrac technology employs 2 levels of tracking, 1 during scan acquisition and 1 during the post processing phase.
“This dual approach to removing artifact is a sophisticated process,” says Wei. “Our scientists collaborated with Massachusetts Institute of Technology to develop the algorithm.”
AngioVueHD OCTA technology is uniquely suited for patients who have retinal disease associated with changes to the vasculature, such as wet AMD and diabetic retinopathy, because it quickly provides high-resolution images of the retinal vasculature. “By providing a wider field of view along with improved resolution, physicians can see the vasculature more clearly,” Wei says. “They are also able to assess for pathology that arises in the mid periphery more easily.”
For patients with wet AMD, Dr. Waheed uses Optovue’s AngioVueHD for initial diagnosis as well as for monitoring the size of the choroidal neovascularization (CNV).
“AngioVueHD Montage software lets us view the entirety of the CNV in one image, and thereby monitor its size over time,” Dr. Waheed says. “This is also invaluable for peripapillary CNV as well as for patients with polypoidal choroidal vasculopathy whose lesions may be eccentric and therefore not captured on a 3 mm x 3 mm scan. I was using 6 mm x 6 mm scans to screen these patients, but sometimes I wasn’t confident in the results because of the low scanning density. The higher the scanning density in a wide field of view, the more confident I am in my clinical assessment.”
Additionally, in other conditions associated with CNV, such as myopic degeneration or central serous choroidopathy, where fluorescein angiography may be equivocal, Dr. Waheed says OCTA can decipher CNV noninvasively in just a few seconds.
Dr. Waheed also employs OCTA for diabetic patients. “It provides beautiful structure-vessel correlation and enables me to monitor areas of ischemia in addition to macular edema monitoring with standard OCT,” she says. In patients with subtle visual symptoms, it allows for visualization of a vascular condition such as a mild branch retinal vessel occlusion that may not be immediately obvious upon examination.
More than 225 peer-reviewed clinical studies feature AngioVue’s technology, which is more studies than all other manufacturers combined, Wei says. Dr. Waheed and colleagues conducted a study1 that illustrates the importance of OCTA technology. It evaluated the ability of OCTA to detect early microvascular changes in eyes of diabetic individuals without clinical retinopathy. In observing 61 eyes of 39 patients with diabetes and 28 control eyes of 22 age-matched healthy subjects, changes to the vasculature were observed in 36% of diabetic eyes, and capillary nonperfusion was observed in 21% of eyes.
“OCTA could image foveal microvascular changes that were not detected by clinical examination alone,” Wei says. “The study concluded that OCTA may be able to detect diabetic eyes at risk of developing retinopathy and assess for diabetes quickly and noninvasively.”
ADVANTAGES FOR PATIENTS
OCTA technology benefits patients by reducing the number of FA procedures they require to monitor disease progression. “FA procedures are costly, are time consuming, and have risks,” Wei says.
Dr. Waheed points out that earlier diagnosis and treatment of CNV may result in better long-term outcomes and less vision loss. “But OCTA will need to be integrated into longitudinal clinical trials in order to assess this,” she says. RP
- de Carlo TE, Chin AT, Bonini Filho MA, et al. Detection of microvascular changes in eyes of patients with diabetes but not clinical diabetic retinopathy using optical coherence tomography angiography. Retina. 2015;35(11):2364-2370.