One Step Ahead of Retinal Disease: How OCTA Guides My Treatment Recommendations
By Roberto Diaz-Rohena, MD
Using OCT angiography (OCTA) in my practice has given me a new perspective on the management of both choroidal and retinal vascular diseases. Based on the information OCTA provides about disease activity or lack thereof, I see more, and therefore can do more for my patients.
OCTA in Choroidal Disease
In diseases affecting the choroid, particularly AMD, I use OCTA to:
Monitor the behavior of neovascular complexes. OCTA excels in identifying areas of abnormal blood flow in the outer retina and choroid. It also reveals microvasculature that is not easily seen with other types of angiography. Taking advantage of these capabilities, I watch as an active lesion (“Medusa-like” appearance) regresses after treatment (“dead-tree-branch” appearance), and/or eventually grows “buds” that signal reactivation. With early warning of reactivation, I recommend treatment sooner, prior to exudation and appearance of subretinal fluid on OCT, rather than later (Figure 1).
Choose the most effective anti-VEGF agent and treatment frequency. If based on OCTA a choroidal neovascular lesion is unaffected by or quickly reactivates after anti-VEGF injections, I consider switching to a different anti-VEGF agent to see if it’s more effective or consider adding intravitreal steroids to the regimen. When an anti-VEGF injection is effective for a particular patient, I monitor time to lesion reactivation with OCTA to set the most effective yet least burdensome treatment frequency.
OCTA in Retinal Vascular Disease
I also use OCTA to:
Follow vascular changes in diabetic patients to assess ischemia and risk of disease progression. Unlike other types of angiography, OCTA quantifies parameters that are relevant in diabetic eye disease: size of the foveal avascular zone, vessel density, and capillary nonperfusion. Quantification allows precise visit-to-visit comparisons of changes in these parameters, which tell me how ischemic an eye is becoming. Because the extent of ischemia correlates with risk of progression to severe or proliferative diabetic eye disease, I may recommend anti-VEGF treatment sooner to reduce the risk of progression or I may follow the patient more frequently to monitor changes.
Assess the option of laser treatment for retinal vein occlusion. With OCTA, I can quickly obtain a 12x12 montage image. The system automatically merges a scan of the optic nerve head vasculature and a scan of the macular vasculature. The resulting montage shows me areas of nonperfusion and areas that would be amenable to laser treatment in patients with retinal vein occlusions that aren’t responding satisfactorily to treatment with anti-VEGF agents or steroids (Figure 2).
More accurately identify and manage atypical lesions. OCTA segments the retinal vascular layers so they can be viewed separately. This reveals what is normal and abnormal at each layer, allowing me to distinguish between presentations, such as retinal angiomatous proliferation (RAP) and macular telangiectasia, and more common lesions. I can see whether a lesion is present, where it’s located, and whether it’s associated with blood flow (i.e., whether it’s active or inactive). For example, the vasculature of a RAP lesion appears on OCTA in the inner retina/deep capillary plexus as well as in the choriocapillaris and often in the subretinal pigment epithelium. And the OCT B-scan flow overlay shows where throughout the lesion there is abnormal blood flow. Correct identification of wet AMD variants and other atypical lesions alerts me to the likely need for longer-term treatment, which I can explain to the patient.
More Details, Less Burden
Because OCTA directly assesses the structure of and blood flow through the retinal vasculature, it gives me information sooner or more precisely than other diagnostic technologies. As a result, I’m a step ahead of changes in my patient’s eyes, where I wouldn’t be without OCTA. I can offer treatment sooner when it’s potentially more beneficial. In many cases, I can rely on OCTA and forego other types of angiography for diagnosing and following patients, which is easier for them and more economical and efficient for the practice.
Figure 1. OCTA is being used to monitor this patient with wet AMD, including the response of the neovascular lesion to two different anti-VEGF agents. At the January visit, the patient had no symptoms, and OCT showed no subretinal fluid, but OCTA showed the lesion had increased in size and blood flow. Injection was recommended, but the patient declined. He returned 8 days later, experiencing metamorphopsia. With OCT showing fibrin and OCTA showing additional lesion growth and blood flow, the patient agreed to receive an injection.
Figure 2. 12 mm x12 mm OCTA montage showing non-ischemic branch retinal vein occlusion.
Dr. Diaz-Rohena is head of the Retina Section at Audie L. Murphy Veterans Hospital in San Antonio, Texas, and an adjunct associate professor in the UT Health San Antonio Department of Ophthalmology.