Optical coherence tomography angiography distortion correction in widefield montage images

Optical coherence tomography (OCT) imaging is inherently susceptible to distortion artifacts due to the natural curvature of the eye. This study proposes a novel model for widefield OCT angiography (OCTA) distortion correction and analyzes the effects of this correction on quantification metrics.

Widefield OCTA images were obtained on normal subjects at five fixation spatial positions. Radial and field distortion correction were applied and images stitched together to form a corrected widefield montage image. Vessel area density (VAD), vessel complexity index (VCI), and flow impairment area were quantified on the original and corrected montage images.

This model allows for distortion correction and montaging of widefield images. There were either statistically insignificant or small magnitude changes in vessel density and vessel complexity between uncorrected and corrected widefield images. There was a significant and large difference in flow impairment area, both in the macular (+8.2%, P=0.049) and peripheral areas (+17.2%, P=0.011), following correction. The relationship between pre- and post-correction flow impairment area was non-linear.

Distortion correction of widefield OCTA images can result in clinically and statistically significant differences in important quantification metrics. This effect appears to be most pronounced in the periphery.