OCTA system offers exquisite views

Reviewed by Daniel D. Esmaili, MD

The latest advancement in optical coherence tomography (OCT) technology, a high-density OCT angiography (OCTA) system (AngioVueHD, OptoVue) provides benefits for both surgeons and patients.

Perhaps the greatest advantage is that the technology facilitates improved evaluation of the retinal microvasculature without the patient having to undergo injection of fluorescein dye. The time required for patient evaluations is also decreased substantially.

The new system is a boon for ophthalmologists, said Daniel D. Esmaili, MD.

“The technology has done several things for us, the first of which is that we can now evaluate the retinal microvasculature without having to administer a dye as is required when performing fluorescein angiography,” said Dr. Esmaili, private practice at Retina-Vitreous Associates Medical Group, Los Angeles. “In addition, the system allows us to evaluate patients much more conveniently and rapidly.”

For example, in a patient with wet age-related macular degeneration (AMD), the clinician can easily evaluate the choroidal neovascular lesions periodically in a matter of seconds and as often as desired.

OCTA images are obtained concurrently with the standard structural OCT images, which eliminates extra time that would be added to a different method of evaluation.
 

Closer follow-up

Closer follow-up

“Clinicians can evaluate the choroidal neovascular lesion at every follow-up visit if they so desire, which has given us a way to evaluate and follow these patients a bit more closely and in a way that increases the convenience to the patients by requiring less time,” Dr. Esmaili said.

The safety profile is also improved due to the non-invasive nature of OCTA. Any risk of a dye reaction is eliminated, he pointed out.

An OCTA overview report of the left eye of a patient with diabetic retinopathy. The structural OCT images (horizontal and vertical B-scans) are presented with the four primary OCTA “slabs.” The superficial plexus is enlarged for easier viewing at the lower left. An irregular foveal avascular zone and focal areas of capillary non-perfusion are visualized. (Courtesy of Daniel D. Esmaili, MD.) 

A limitation of this technology is that the range of view of the retina has not been increased in contrast to the view available when using widefield fluorescein angiography, Dr. Esmaili commented.

“In its current form, OCTA provides a view of the macula and the optic nerve and not the peripheral retina,” he noted.

When using OCTA, the clinician has the freedom to choose a particular size image, large or small. The clinician can obtain the maximum density of b-scans in, for example, a 3-mm × 3-mm box, versus an 8-mm × 8-mm box in which the b-scans will provide a larger area of view albeit with less definition, according to Dr. Esmaili.

The company has provided an update to the technology and has introduced a 6-mm × 6-mm HD algorithm that gives both excellent definition and a useful area of evaluation. Software updates also allow for a montage composite view to be obtained by combining optic nerve and macula images.

Patients with AMD who are being followed have a substantial treatment burden. These patients may be asked to undergo monthly evaluations that include imaging, dilated eye examinations, and perhaps an injection if needed. An important consideration is that many patients are elderly and many require that they be transported to these evaluations by family members who may have other obligations.

“The feedback from our patients is that the non-invasive and rapid acquisition time of OCTA is creating shorter visits that are safer and more comfortable. Our patients are appreciative of this and have really embraced this technology,” he said.

Detailed imaging

Detailed imaging

From the standpoint of the practitioners, the details of the retinal microvasculature provided by OCTA are “absolutely exquisite.”

For example, in patients with diabetic retinopathy or retinal vein occlusion, the perfusion status of the macula is easily recognized as are areas of capillary dropout.

“This ability is highly useful when managing these patients,” Dr. Esmaili said.

Use of OCTA compared with fluorescein angiography is also managing to streamline ophthalmology practices, he pointed out.

When performing fluorescein angiograms, the technicians are engaged with the patients for 20 to 30 minutes because of the need to access veins, take and process photographs, and transmit large data sets through a network

More efficient offices

“Using OCTA, we have noticed that our practice is running more efficiently. Patients are evaluated faster and we are staying on time in the clinic,” he noted.

“OCTA is the next step in the evolution of OCT, and like all new technologies, there is a learning curve,” he said. “In the case of OCTA, it takes some practice for the ophthalmologist to appreciate normal versus abnormal findings and to identify artifacts. For our technicians and patients, it takes some practice to be able to acquire good images. Once a level of comfort is achieved, the benefits can be powerful.”

Daniel D. Esmaili, MD

E: desmaili@yahoo.com

Dr. Esmaili is a speaker for OptoVue.