Principles of OCTA and Applications in Clinical Neurology

Abstract

Purpose of ReviewThe article reviews the recent findings on the use of optical coherence tomography angiography (OCTA) in neurology.Recent FindingsOCTA is a new addition to the powerful and complementary technology of the OCT. Due to its noninvasiveness, and reproducibility, it is possible to obtain high-resolution 3D images of the vessels of the human eye. As the vessels of the retina with the presence of endothelial cell’s tight junctions resemble the brain vessels, it was hypothesized that the imaging of the retinal vessels might bring insight into brain vessels. OCTA has been effectively used to predict retinal vessel abnormalities in dementia, demyelization, optic disc neuropathies, and inherited degenerative diseases. Most common findings were decrease of vascular density and flow and an increase of avascular zones.SummaryAlthough OCTA is a relative new technology, recent studies show that it can be successfully applied in neurology.

Comparison of foveal avascular zone and retinal vascular density in healthy Chinese and Caucasian adults

“…; Teper et al. ; Wylęgała ) reported a significant difference between FAZ in the superficial and deep plexus; however, this finding may not be meaningful as Campbell et al. showed that all the vascular layers merged into one to create a single FAZ.…”

“…Currently, several OCT devices with dyeless angiography modality are available; they differ in the use of algorithms, OCT technology and nomenclature (Wylęgała ).…”

“…In our centre, the number of fluorescein angiography in patients with vascular age‐related macular degeneration (AMD) is down to 20% of its value before the inclusion of OCT‐A in our standard of treatment. This modality is, however, not only limited to the diagnosis of disease, but it also has a greater potential in studying physiological aspects of the blood flow and vascular architecture in healthy subjects (Wylęgała ; Wylęgała & Wylęgała ). Optical coherence tomography angiography (OCT‐A) measures the changes in parameters such as phase or amplitude between different B‐scans of the same location.…”

“…The ones located on outer parts of the inner plexiform layer and inner parts of the inner nuclear layer are called intermediate capillary plexus, and the ones below the outer parts of the inner nuclear layer are called the deep vascular plexus. Along the retinal nerve fibre layer, there is a fourth plexus called the radial peripapillary vascular plexus (Wylęgała ). In the initial period of the use of OCT‐A, most studies measured FAZ by using manual tools in ImageJ or built‐in software (Wylęgała et al.…”

Reproducibility, and repeatability of corneal topography measured by Revo NX, Galilei G6 and Casia 2 in normal eyes

“…Some OCT systems use swept-source technology featuring lower resolution but faster acquisition rate [13]. Others relay on spectral domain producing a smaller acquisition window but with a higher image quality [14]. The biggest advantage of AS-OCT over a Scheimpflug based system is that the numeric values are accompanied by the presence of high quality images that are superior in terms of resolution [15].…”