OCT ANGIOGRAPHY

Publication Exclusive: Noninvasive OCT angiography allows for detailed visualization of retinal vasculature

September’s announcement by Carl Zeiss Meditec that its AngioPlex OCT angiography technology had received 510(k) clearance from the FDA set the stage for other systems to likely also soon become commercialized in the U.S. The technology allows extreme close-up imaging of the retinal vasculature for assessing retinal vascular diseases and holds potential for guiding treatment decisions and monitoring patient responses to therapy.

“Over the past 20 years, OCT has developed rapidly as a ‘noninvasive’ method of imaging for medical diagnosis and defining activity criteria, such as intra/subretinal fluid, hyper-reflective dots and dense intraretinal areas,”Gabriel J. Coscas, MD, emeritus professor of ophthalmology at the University of Paris XII in Créteil, France, said. But over the past 2 years, it was found that additional information useful for treatment decisions can now be gained with OCT angiography (OCTA).

“This huge progress consists of having both functional and morphological assessment from a single dye-less examination,” Coscas said. “The rapid and noninvasive nature of OCTA allows for easier follow-up of morphological and functional changes in prolonged, repetitive and even monthly evaluations.”

SriniVas R. Sadda, MD, president and chief scientific officer of the Doheny Eye Institute in Los Angeles, is attracted to OCTA in part because of the ability to visualize the retinal microcirculation noninvasively without the use of dye, while at the same time reaping the benefits of OCT imaging.

OCTA offers a tremendous amount of contrast. In many ways it provides more detail and better resolution than traditional fluorescein angiography,” Sadda said, citing the ability to visualize the radial peripapillary capillary network near the optic nerve.

“That network is so fine and so tightly packed that with a traditional fluorescein angiogram we could never see it. But now with OCTA, we are able to observe the network,” Sadda said.

This visualization also extends to the central part of the macula.

“With OCTA, you have a lot more confidence for assessing retinal capillary perfusion status, which can be very helpful in understanding various retinal vascular diseases, with diabetic retinopathy and retinal vein occlusions being the most common,” Sadda said.

OCTA is also being used to evaluate macular telangiectasia. “We are able to see the vascular anomalies in so much more detail,” he said.

Another advantage of OCTA’s superior contrast is the ability to glean more quantitative data. Whereas fluorescein angiography typically relies on subjective categories to define mild, moderate or severe loss of blood vessels, OCTA has the potential to use automatic computer algorithms to quantify the level of capillary loss, Sadda said.

“[Optovue] is starting to provide numerical retinal vascular data such as flow density analysis. We can expect that all companies in short order will add quantitative metrics. Once you have quantitative metrics, you can follow disease much more precisely and understand the relationship between these anatomic parameters and other visual function measures,”