Date Published: October 2, 2018
Publisher: Public Library of Science
Author(s): Siqing Yu, Beatrice E. Frueh, Dagmar Steinmair, Andreas Ebneter, Sebastian Wolf, Martin S. Zinkernagel, Marion R. Munk, Demetrios G. Vavvas.
To analyze retinal blood flow before and after cataract surgery using swept-source optical coherence tomography angiography (SS-OCTA).
Prospective observational study. Consecutive patients were recruited and scanned using SS-OCTA before and after cataract surgery. Laser flare photometry were performed post-surgery. Perfusion and vessel density of superficial (SCP) and deep capillary plexuses (DCP) of the 3 × 3 mm images as well as foveal avascular zone (FAZ) measurements were assessed. Vessel continuity, vessel visibility and presence of artefacts were evaluated by two blinded graders using a predefined grading protocol.
Thirteen eyes of 12 patients met the inclusion criteria. There was a significant increase of perfusion and vessel densities in both the SCP and the DCP after cataract surgery within the 3 × 3 mm images. Significantly better distinguishability of FAZ border was observed postoperatively in both SCP and DCP, however, FAZ area and perimeter measurements did not significantly change after cataract surgery. Mean number of motion artifacts in SCP and DCP numerically decreased by 37% (P = .089) and 42% (P = .080).
Lens opacities have a significant influence on retinal blood flow measurements in SS-OCTA and should be considered in quantitative vessel analysis. Inflammation may also impact the assessment of density parameters. FAZ measurements seems to be the most robust parameters in terms of media opacity.
Optical coherence tomography angiography (OCTA) is the latest imaging modality that can be used to image the microvasculature of retina and choroid without dye injection. Instead of staining vasculature as fluorescein angiography (FA), OCTA is based on the concept of “motion contrast”. It visualizes blood flow by detecting dynamic structures among other static tissues such as the neurosensory retina. Thus, with its features of non-invasiveness, repeatability, OCTA rapidly gained widespread usage in the investigation, evaluation and monitoring of retinal and choroidal vascular diseases.[1–3]
Many studies showed that OCTA can be used to ocular pathology monitoring as it is easy to use, has short acquisition times and is noninvasive. However, it is still limited in detecting certain anatomical features, such as microaneurysms, vessel loops, leakage, and some vessel segments.[10,16] This prospective study is the first to illustrate that cataract can significantly influence quantitative vasculature measurements even in high quality images using SS-OCTA.