This iteration of OCTA is based on SD-OCT platforms. An algorithm is used to detect blood flow as a contrast medium and repeatedly sample sections of the macula. “This technology is very interesting and exciting in retina,” Dr. Chen said.
There are a few advantages of OCTA compared with FA. First, the former is not invasive and no fluorescein dye (with its potential for allergic reactions) is injected into the patient.
Second, OCTA offers superior details of different vascular layers of the retina that previously were not available by other imaging devices. The technology allows segmentation of the retina and the potential to detect changes and review them after the patients have undergone imaging.
Dr. Chen outlined a case of sickle cell retinopathy in a patient. Despite the absence of visual symptoms, vascular changes can be taking place in the retina. An OCTA from this case showed the presence of subtle vascular changes in the macula.
A flow void was visible with lack of circulation. A corresponding OCT image shows thinning in the temporal macula, suggesting that a vascular event occurred in that area in this asymptomatic patient.
Perhaps the greatest advantage, according to Dr. Chen, is that OCTA provides a great deal of quantitative information.
“We can skeletonize the vascular images and quantify the actual vascular density,” Dr. Chen said. “We can also look at the foveal avascular zone and its irregularity to better understand the changes in these patients.”
Newer imaging technologies continue to redefine and refine physicians’ approach to complex retinal diseases, Dr. Chen concluded.