Optical coherence tomography (OCT) has revolutionized the practice of ophthalmology as arguably one of the most important diagnostic tools available. Now, OCT angiography (OCTA), a relatively new non-invasive imaging technique (see “OCTA systems,” below), extends the possibilities of OCT technology even further. OCTA provides a detailed view of the retinal vasculature that can be isolated from OCT image data.

Despite its benefits, many ophthalmology practices fail to use OCTA to its fullest extent. According to Darrin Landry, CRA, OCT-C, an ophthalmic consultant for Bryson Taylor, Inc., who literally wrote the book on OCTA, as few as a quarter of the practices he’s worked with had been using the technology to its full potential. That equates to a lot of missed opportunity.

In this article, Mr. Landry discusses how to better take advantage of the opportunities OCTA offers.

Understand OCT and OCTA

Using this technology more fully starts with understanding what it can offer. While OCT illustrates the anatomical structure, Mr. Landry says that OCTA allows for a view of the vascular structure—and that’s the fundamental difference between the two. But because OCTA still uses OCT technology, in addition to the view of vascular complexes, you also can acquire an OCT scan with which to compare.

“OCTA also uses ‘en face’ imaging for scanning multiple layers from the anterior retina all the way through to the choroid,” explains Mr. Landry. “This is a major advantage because we can look at every single layer and find the exact layer in which there is an abnormality in the blood vessels. Being able to pinpoint the exact source of the neovascular complex is not something we’re able to do with regular OCT or sometimes with dye angiography, which is ultimately only a single plane view.”

These abilities are valuable for many pathological conditions—but most notably for age-related macular degeneration (AMD) and diabetic retinopathy.

“For instance, in neovascular AMD, we can actually see the neovascular complexes instead of looking at dye angiography and leakage,” Mr. Landry explains. “We can see every single capillary, and because blood is actually moving we can identify the entire lesion and its source.”

Conversely, Mr. Landry says OCTA also can illustrate where there is no movement, in the case of impaired perfusion. On an angiogram, this is obvious because the dye stops. OCTA works in a similar fashion but in a noninvasive system.

“We’re not injecting dye, and some of these systems can perform the imaging in as quickly as 6 seconds with no dilation,” Mr. Landry says. “This is where OCTA can shine.”

Expand the possibilities

Despite the possibilities of what OCTA can offer, Mr. Landry says many practices are not thinking “outside of the box.”

“If it can look at blood flow and what’s moving in the back of the eye, ultimately you can use it for any application that involves vascularity—any pathological condition that involves blood vessels,” he says.

For example, one area where Mr. Landry uses OCTA a lot is to identify macular telangiectasia (MacTel), where blood vessels around the fovea leak, become dilated, or both.

“On an OCTA, I can see impaired capillary perfusion and microaneurysms, and that’s important as MacTel can progress to become a retinal angiomatous proliferation.¹ This is one of the most underutilized areas of OCTA that stands to be incredibly beneficial,” he says.

In terms of why more practices aren’t using OCTA to the full extent, Mr. Landry says it boils down to training. He says OCTA is not a “point-and-shoot device,” like some professionals may be used to with fundus photography and even OCT. Overall, there’s a lack of formal training for this type of imaging modality. In addition, Mr. Landry says that OCT technology has become so user-friendly that almost anyone can do it, albeit not always well—but that doesn’t translate the same way to OCTA.

He says that ensuring OCTA is better used to its full extent really does come down to education and training.

“I’ve taught all over the world, and lack of training remains the No. 1 barrier,” he says. “Every time that I’m training a technician on OCTA, I hear them say, ‘I didn’t know it could be used for that.’ You can read a book to understand it, but acquisition is a whole different animal.”

That’s why Mr. Landry says it’s ideal to bring in a consultant who can assist with the training. He also says it can help to reach out to practices that successfully use OCTA and ask staff members for their tips and ideas.

“Once you understand the fundamentals of what it can do, you start to find more ways to use it and it can become a tremendous benefit to your practice,” Mr. Landry continues.

Enhance knowledge and increase utilization

Mr. Landry offers several tips to help better understand and utilize OCTA technology:

• Scan patients who have no diagnosis. One word of wisdom that Mr. Landry offers in being able to better understand what you’re looking at is to take the time to scan some patients who have no specific diagnosis.“You have to know what normal looks like,” he advises. “When we first started out with OCTA, we just scanned all of the patients that came through the door. If you’re new to this or not grasping it yet, use it on as many patients as you can until you fully understand what normal looks like and then you can begin to notice even the smallest changes.”
• Close communication and expectation gaps. Mr. Landry also recommends that ophthalmic professionals maintain communication with the clinician, as any gaps in communication and expectations can have a negative impact.“If the imager doesn’t know what the clinician is looking for, they’re probably not going to find it,” he adds. “Up your game as an imager by communicating and taking the time to continually learn. It ultimately makes you indispensable within the practice.”
• Think outside the box. If Mr. Landry were to sum up his most important piece of advice, he says it would be for more practices to begin thinking outside of the box, for example, using OCTA to identify MacTel, as described above. That’s truly the best way to use OCTA more fully.“Just because a diagnostic tool is designed for one purpose does not mean you cannot stretch those boundaries,” he says. “Push the envelope—within reason of course—and don’t limit yourself to what you can do.” OP

REFERENCE:

1. Chew E, Friedlander M. Update on Idiopathic Macular Telangiectasia Type 2. Retinal Physician. 2020;17(7):21-23.