A History of OCT-A
Many see optical coherence tomography (OCT) angiography as a promising new technology, but David Huang, MD, PhD, Peterson professor of ophthalmology at the Casey Eye Institute at Oregon Health and Science University in Portland, OR, says the technology has been “brewing in the background” for over a decade.
“We were just waiting for the OCT system hardware to run fast enough and for the angiography algorithm to be efficient enough to produce a high-quality angiogram in reasonable scan time,” he said, talking about the history of OCT.
“Younger ophthalmologists probably see OCT as a technology that came out of Oxford, fully functioning,” he joked, “but 2016 marks its 25th anniversary. OCT spent close to 10 years in the wilderness before it became a profitable product.” He added that the persistence of Carl Zeiss Meditec (CZM) “in developing time-domain OCT is what allowed pioneering clinicians to learn how to use it, to improve patient care, that made it part of their standard care.”
Jay Wei, MS, left CZM to start Optovue, where he oversaw Fourier-domain OCT development, which is also known as spectral-domain OCT.
Dr. Huang noted it’s “pretty amazing” that the two angiography algorithms used clinically both originated at his university.
Ruikang Wang, PhD, developed optical microangiography(OMAGin 2011, and Dr. Huang introduced split-spectrum amplitude decorrelation angiography (SSADA) in 2012. Dr. Wang’s algorithm became the basis for the CZM system (introduced in the US as AngioPlex in 2015), whereas Dr. Huang’s algorithm became the basis for the OptovueAngioVue (approved in the US in 2016).
But there are still commercialization challenges, even though the technology allows retina specialists to determine if a patient has leakage or if an avascular area is growing, Dr. Huang said, including the need for a new CPT procedure code.
“It’s going to take a few years for these major clinical applications to become standard of care. I have no doubt that it will happen,” he said.
David Huang, MD, PhD
Dr. David Huang is the Peterson Professor of Ophthalmology and Professor of Biomedical Engineering at OHSU. Dr. Huang received an MD from Harvard, a PhD from MIT, ophthalmology residency training at the Doheny Eye Institute/USC and a cornea fellowship at Emory University.
David Huang, MD, PhD: OCT angiography and intra-operative OCT: I think these are not just trending topics because of their novelty, but have solid reasons to grow over the next 5 to 10 years into major segments of the technology of retinal imaging market. And most ophthalmologists are aware of OCT angiography as a new technology that sprang out in the past 2 years, but actually I think it’s been brewing in the background for quite a while, for at least ten years in Professor Yasuno’s lab in Japan and with Dr. Ricky Wong. And so what took us so long to come into the clinic? Well, it was waiting for the OCT system hardwares to run fast enough, and for the angiography algorithms to be efficient enough to produce a high quality angiogram in reasonable scan time. You can think of this as in a telecomm analogy. To get streaming video, you have to have a fast optical pipe, and you need very efficient compression algorithm. So it’s actually pretty amazing that the 2 angiography algorithm that became clinically implemented both came out of Oregon Health and Science University, where I’m at. And the first was Dr. Ricky Wong, who developed something called OMAG back in 2011, and my lab developed something a little bit later called SADA around 2012. And both of these were patented and licensed, and OptiVue developed a clinical OCT angiography platform, as did Zeiss at around the same time. OptiVue launched the first OCT angiography system in 2014 called AngioVue internationally, and several companies at that time also became interested in this area and developed prototypes. In 2015, Zeiss got FDA approval of AngioPlex and launched OCT angiography as a product. And other companies also entered the market. 2016, this year, AngioVue finally got FDA approval belatedly, and there are more commercial entries for this technology. I was also asked to present something of OptiVue’s history in OCT technology evolution. So the young ophthalmologists probably see OCT as a technology that came out of a box with fully functioning softwares and normative datas. But actually there’s quite a history behind this. This year is actually the 25th year anniversary for the invention of OCT back in 1991. And OCT actually spent I think about ten years in the wilderness before it became a profitable product. And I like to thank Carl Zeiss Meditech for the persistence in developing the time domain OCT technology that allowed pioneering clinicians to learn how to use it to improve patient care and made it part of the standard of care. And Mr. Jay Wei was in charge of advanced development, and then the OCT product at Zeiss between 92 and 2003. And then he started his own company called OptiVue to develop Fourier-domain OCT, also known as either – there’s two variants: spectral domain or swept source in 2006. And then came out with other first of a kind products including OCT angiography in 2014. And there are a couple bases for this product. One is a very efficient algorithm called SADA that splits the spectrum to obtain more effective image frames without increasing the image scan time. And another is to deal with the motion artifacts using registration or tracking to improve the image quality. So what are the killer apps for this technology? I think one so in choroidal neovascularization, neovascular AMD, where for example in this slide, you can see the choroidal neovascular network in yellow. Because OCT is three dimensional, you can divide the retina into layers, and yellow is flow in the outer retina, in contract with the inner retinal flow in purple. And you can see here within a cycle of anti-VEGF treatment you actually have shut down and then re-opening of the CNV network. And that’s information you cannot get with structure OCT or fluorescein. Another potential killer app is looking at capillary dropout. You can see it more clearly with OCT angiography. And this is very sensitive for picking up diabetic retinopathy. So what are the challenges facing OCT angiography commercialization? Well, one is clinical acceptance. It’s going to take a few years for these major clinical applications to become standard of care. But I have no doubt that it’ll happen. If you were around in 1999, you remember retinal specialists who said OCT doesn’t give them any useful information that they didn’t already know. And these people are today using OCT every day. So I’m sure this new information out of OCT angiography will learn how to use them in several years. Another is FDA approval. There’s a lot of incremental improvements in OCT angiography, getting rid of the artifacts and measuring quantifications. And – Oh, OK. So that’s delayed by FDA. And then finally, most importantly, you need a CPT code to pay more than standard OCT for this to be worthwhile. Thank you.