OCTA from the Ophthalmic Photographer’s Perspective
By Zafiirah Khodabukus, COA
At Mid Atlantic Retina, where I’m an ophthalmic photographer, we use OCT every day. We also utilize OCT angiography (OCTA), because it provides our physicians with an additional, entirely new way to evaluate the retinal vasculature. Since OCTA is noninvasive, they find it particularly useful for supplementing the diagnostic information obtained from OCT as well as an alternative to fluorescein angiography in patients who have poorly accessible veins or are likely to be allergic to the fluorescein dye.
OCTA image acquisition isn’t difficult for our photographers, and the OCTA software is easy to navigate. Although manual focusing is possible, the autofocus capability tends to result in the best quality scans. For learning the basics of using the technology, a 2- to 3-hour training session with a company representative has been sufficient.
In fact, the biggest challenge of working with OCTA has little to do with the technology itself. Instead, the challenge is working properly with patients, which is not an uncommon issue in retina practices. To obtain quality OCTA scans, patients must remain still and not blink for the few seconds the images are being captured. This may be difficult to accomplish, especially for patients with extremely poor vision and those who have a difficult time with central fixation.
Our approach is to coach patients through each step of the test. Before we even position patients at the machine, we talk them through the process. We explain the purpose of the test and how it’s just like their earlier OCT scan(s) when they focused on the blue light with just one difference — not being able to move or blink for a moment. We let them know that we’ll tell them when to blink and when not to. We reassure them that if the first scan isn’t perfect, we can try again, which isn’t harmful to the eye. Once they’re in position on the head and chin rests, we continue to talk so there are no periods of silence during which they may wonder what to do. Frequent encouragement, such as “you’re doing great” also helps. At the appropriate time, we say “don’t move, don’t blink ... don’t move, don’t blink ... until the scan is complete. As soon as it is, we let them know they can blink and sit back.
With the scan complete, we check the quality of the resultant overview image (Figure 1). It doesn’t take long for a photographer to learn to recognize the difference between a good-quality scan and a poor-quality scan. The OCTA software can remove many of the artifacts that may occur, and we check for signs that the patient blinked or moved during the test. A dark line anywhere on the image indicates a blink, and results are essentially missing in that section. If the patient moved during the scan, the blood vessels in the image appear blurry. If a patient had trouble focusing, the image looks as if it’s shaking. Severe myopia or a dense cataract can cause distortion at the image borders. In any of these scenarios, we simply retry the scan. The entire process rarely, if ever, takes longer than 5 minutes and typically takes less than 2 minutes.
An Easy Transition
With a bit of training, experience, and patience, any practice’s imaging team should be able to develop its own script and patient-centered techniques for performing OCTA, with little if any disruption in the practice’s typical daily work flow.
Figure 1. (A) A poor-quality image due to patient blinking and movement. (B) A good-quality image was obtained when the same patient was re-scanned.
Zafiirah Khodabukus, COA, is lead photographer with Mid Atlantic Retina in Philadelphia, a practice serving patients in Pennsylvania, New Jersey, and Delaware.