The Past, Present, and Future of OCT, Part 1: Transformative Milestones

To coincide with the announcement of our new Hall of Fame inductees – which sees David Huang, co-inventor of optical coherence tomography (OCT), and Dennis Lam, leading clinician, entrepreneur, and philanthropist, added to the esteemed roll-call – The Ophthalmologist recently convened a KOL roundtable to explore the transformative power and future potential of OCT.

For this special event, Huang and Lam were joined by Ophthalmologist Power Listers (see sidebar), who discussed their observations and experiences of how OCT technology has revolutionized the practice of ophthalmology and patient care.

In part one, we ask the panel, “What are the most transformative milestones in OCT’s developments since its inception?”

The panel

Highlights of that discussion follow.

Dennis Lam: I think OCT really is one of the breakthrough technologies, one that changes the practice of ophthalmology. In the past, when we had a patient with maculopathy we were kind of stuck; if we didn’t know the details of the pathology, we’d have to do guesswork. But with OCT technology, even in the beginning, we could identify structural changes in the retina, assess macular holes, create a whole lot of data to help us diagnose and treat patients. Nowadays we have OCT Angiography (OCTA), for example, enhancing our understanding of vascular changes in medical macular diseases. It is now an extremely important part of our ophthalmic practice.

Nadia Waheed: I think that David Huang and his colleagues at MIT – James Fujimoto, Carmen Puliafito, Eric Swanson – really seeded ophthalmology with perhaps the most transformative technology that we have seen. I was fortunate enough, when I started at the New England Eye Center at Tufts Medical Center, to see the original time domain device from MIT that had been deployed at the Eye Centre. We had newer generation devices by then, but the original device was still there in the OCT laboratory.

One thing that helped the technology to find its home in the clinic was the very close collaboration between the MIT group and the clinicians at the New England Eye Center. If you look at the papers that were published as part of the collaboration in those first few years you see that thousands of patients were imaged, generating an atlas of beautiful images of various different retinal pathologies. And ophthalmologists started to see that OCT could show them so much more than they could see with the naked eye. In macular degeneration and diabetic macular oedema, for example, you could see the fluid accumulating way before a patient's vision declined. I think another thing that helped define the utility of OCT was that this was just around the time when anti-VEGFs were being tested for neovascular AMD, and here was a modality that showed the efficacy of the therapeutic in real time.

Michael F. Chiang: When I was training -- I finished my clinical training in 2001 -- the way we learned ophthalmology was by putting contact lenses up to somebody's eye and learning about the nuance of the macula or the optic nerve head. It was basically descriptive and qualitative; you looked at something and drew a picture of what you saw, and that was the fundamental knowledge base of ophthalmology. Now it is totally different. There has been a huge paradigm shift from qualitative and descriptive to quantitative and objective. The shift has happened so gradually over 20-plus years, and sometimes people don't stop and realize just how different the field is now because of OCT technology. It is an awesome achievement, I think.

Anat Loewenstein: Many of the clinical skills are now just not needed. It's very similar to cardiology. My mom was a cardiologist, and she praised herself that she could diagnose everything with a stethoscope. Now my son, who is a cardiologist, focuses his exam on echocardiography. I'm sure that the ophthalmology residents, even though we try to teach them, don't bother to see, for example, if the pigment epithelium is elevated, or if there is a build-up of subretinal fluid. Things that we spent so much time learning, we just see it with the technology now, we just know.

Keith Barton: I'd say the technology has taken it even further than that, because we don't even need to see the patients now. In glaucoma, for example, during COVID-19 when patients didn't come in, Moorfields Eye Hospital set up a huge remote monitoring service. They put up remote hubs where patients came in, had their eye pressures checked and had their visual fields checked on an OCT. Sure, we could have checked eye pressures and fields in the past, but without OCT we would have had disc photos. OCT gives you so much more than just the appearance of the optic disc. If the vision's down you can see if there's macular oedema, for example. So, even in a glaucoma clinic, the technology has really transformed care, not just for the early diagnosis of glaucoma, but by actually allowing all the stable patients not to have to come to clinic.

David Huang: I want to thank everyone for talking about the current “killer apps” for OCT, which have definitely been transformative. But even before anti-VEGF therapy, we had already experienced several pivotal moments in the development of OCT, when we changed direction in terms of our main emphasis.

My research at MIT started in part due to a collaboration between Jim Fujimoto and Carmen Puliafito. Originally they were looking at the cornea. Of all things, Carmen (a retinal specialist) was interested in measuring the depth of radial keratotomy (RK) incisions, and more importantly, laser ablation for photorefractive keratectomy (PRK) in the study of corneal refractive surgery, which was a hot topic at that time.

My first target for interferometry was simply measuring corneal thickness, and then we also looked at retinal thickness. When I saw the internal signal from the retina, I realized that this could be an imaging technology. That’s when we pivoted from simply measuring thickness to developing an imaging technology, and where Eric Swanson came in with the advanced photonic technology to make the system sensitive and fast enough for imaging. I also want to acknowledge Joel Schuman, who at that point brought in all the eye samples and showed me how to access the retina and make the initial images. Joel already had the vision that this nascent technology could be useful for retinal evaluation.

We also looked at several other targets like coronary artery plaques and gastrointestinal (GI) mucosa, but the retina proved to be the most impressive, because you could see the internal layers. Those images showed the technology had clinical potential. I want to credit Joe Izatt and Michael Hee for their contribution in building the clinical prototype, which went to Massachusetts Eye & Ear Infirmary and then to Tufts for the initial clinical demonstrations. Then Humphrey Zeiss acquired the technology. John Moore was President of Humphrey Zeiss, the company that resulted from the Zeiss acquisition of Humphrey Instruments. Moore’s vision originally was to apply OCT to glaucoma, because the Humphrey Field Analyzer was – and still is – dominant in glaucoma.

It was fortunate that the Boston team continued their research into retinal diseases, which Carmen Puliafito oversaw before Jay Duker and Nadia Waheed took over this line of research at Tufts. Initially, they were looking at cystoid macular edema, macular holes, epiretinal membrane, and vitreoretinal traction to guide surgery. Back then (1990s), clinicians could reasonably claim that they could see these diseases better than OCT could by direct examination. But by the time that OCT technology had advanced into the 2000s it was hard to support such arguments. And then anti-VEGF therapy became a hot topic and you needed quantitative measurements of retinal thickness that only OCT could provide.

As we entered the modern era, OCT became the dominant imaging technology in ophthalmology. But before that, between 1991 and 2000, there were many times when we wondered whether OCT was viable and searched through a number of potential applications. So, there was a lot of evolution even before everyone became aware of OCT.

Anyway, that’s my ancient history perspective!

Just finally, the original OCT machine that I built at MIT in 1990 doesn't exist anymore, somebody took it apart for parts for other projects. So, the preserved early OCT system at Tufts is not the original, but it may indeed be the oldest existing one!

Stay tuned for Part 2, in which the panel discusses the developments in home OCT and remote monitoring. To see the full video of the roundtable, please register here.