SD-OCT is providing reproducible, high-quality, registered images to assess the treatment response in macular disease.
In our seven-doctor retina practice we use a variety of imaging equipment; however, one of the constants is our reliance on spectral-domain optical coherence tomography (SD-OCT). Fifteen years ago, I was fortunate enough to train at the Tufts University/New England Eye Centre with clinician-scientists who were instrumental in developing OCT technology. Now what stands out to me is the resolution we can obtain with SD-OCT, specifically the high-resolution SPECTRALIS multimodal imaging platform (Heidelberg Engineering, Inc.) is as good as that of our investigational devices from the early-to-mid-2000’s. I am eager to see where we will be in another 15 years.
Here I will overview our practice’s approach to managing diabetic eye disease.
Imaging is integral to the management of diabetic eye disease, therefore, all newly referred patients in our practice receive baseline imaging along with the clinical exam.1 What we do in the clinic should mirror, as best as possible, the best practices from randomized, controlled trials. Those lean heavily on angiography and especially OCT imaging to determine treatment selection and frequency. Therefore, baseline imaging almost always includes those two modalities at the minimum. We also, secondarily, may obtain ultra-wide colour fundus photography (Zeiss and Optos platforms) in our offices where that technology is available.
The sequence of follow-up imaging is determined by disease severity and treatability, whether it be diabetic macular oedema (DMO), which is the most common manifestation of diabetic retinopathy (DR) which we treat, severe non-proliferative DR, or proliferative DR.2 Patients with disease for whom treatment is initiated we see more frequently to gauge their response.
The image registration we can obtain with SPECTRALIS is remarkable, and the TruTrack Active Eye-Tracking feature allows me to compare live images to understand progression. Rather than relying on maps, I prefer to scroll through the scans for a line-by-line comparison. This feature is especially helpful when initiating, changing, or adding treatment: for example, adding focal laser to an area of macular oedema that is not responding to first-line anti-angiogenic therapy or adding a steroid for a patient who still has centre-involving swelling despite frequent anti-angiogenic injections. When it comes to DMO, we value the ability to objectively determine if treatment is providing a measurable improvement.
In the setting of proliferative diabetic retinopathy, I will occasionally perform repeat angiography; however, I generally do not repeat angiography frequently. Although overall, surgeons do less angiography than in the past, ultra-widefield angiography is important in the initial assessment of patients with suspected proliferative disease to ensure control and a complete laser pattern. In our practice, we use the Heidelberg Engineering Ultra-Widefield Module for that application in addition to other ultra-widefield platforms.
SPECTRALIS imaging is well tolerated by patients, and it can be done at any office visit. The patient remains seated in one spot while receiving OCT, angiogram, and ultra-widefield angiogram imaging at the same machine. Regardless of dilation status, we obtain a high-quality image, and the laser light wavelength is not overly bright as may be the case with other systems. For some widefield platforms, patients must be extremely dilated to obtain high-quality images and artifacts can be an issue. SD-OCT is by far the most utilitarian imaging modality available.
OCT and ultra-widefield colour images play a key role in disease education, and I use them with all my patients to explain their disease process. In DMO for example, I will show patients an example of a normal OCT versus their eye with a swollen macula. By seeing their image, they better understand their disease severity and how close to normal they are. Using the ultra-widefield colour image, I point out the red dots that indicate DR explaining that they have bleeding in or in front of their retina and, depending on severity, that that may be treated.
I also love talking to patients about blood sugar control. I give all my diabetic patients one homework assignment: learn your haemoglobin A1c – whatever that number may be – and make a numeric goal with their endocrinologist or primary care doctor. Only about half of my patients know what their HbA1c is when they first come in. I tell them that blood sugar is the fuel for the diabetic fire; they can remove the fuel and put out the fire over time by controlling HbA1c. I explain that their disease comes from a combination of the duration and severity of their diabetes. I say, “if you have diabetes and intend to live—and see—for a long time, you must get your blood sugar under control to reduce your risk of vision loss.”
I am currently involved in a large initiative to democratize diabetic eye care by moving it into a non-traditional setting. Patient access and education are some of the biggest gaps in diabetes care. Repeated, patient-friendly messaging can go a long way to helping this significant public health problem. Diabetes is a US pandemic that preceded COVID-19 by many years and will be around long after COVID recedes. We must ensure that the approximately 50% to 60% of patients with diabetes who do not go to eye exams have a pathway to care and treatment.3 Having imaging that is high-quality, straightforward to obtain, and reproducible is a large part of their clinical care.
Diagnostic imaging is certainly required as part of the standard of care for managing diabetic eye disease. At the bare minimum, the physician must be able to obtain high resolution OCT images and high-quality angiograms to assess the initial anatomy and pathophysiology and to track treatment. Both of these we can perform with SPECTRALIS.