A novel strategy for quantification of panoramic en face optical coherence tomography angiography scan field.

Abstract

To compare the retinal area measured on a panoramic en face optical coherence tomography angiography (OCTA) image with that on an ultra-widefield fluorescein angiography (UWF FA) image. Sixteen eyes (11 with branch retinal vein occlusion, 2 with central retinal vein occlusion, 1 with branch retinal artery occlusion, and 2 with hypertensive retinopathy) were included in this study. A panoramic en face OCTA image was created from five single non-panoramic en face OCTA 12 × 12-mm images. The panoramic OCTA image was superimposed on the corresponding UWF FA image after image registration; the total retinal area was measured using the grid displayed on the UWF FA image. The area on the UWF FA image was measured using stereographic projection software. The area of retina measured on a single non-panoramic 12 × 12-mm en face OCTA image, a panoramic en face OCTA image, and a UWF FA image was 152.4 ± 3.4mm2, 369.6 ± 26.9mm2, and 813.1 ± 24.4mm2, respectively (P < 0.0001). The panoramic OCTA image was 2.42-fold larger than a single non-panoramic 12 × 12-mm OCTA image and 0.46-fold smaller than a UWF FA image. Grid-based measurements using an OCTA image superimposed on the UWF FA image enabled measurement on the panoramic en face OCTA image with minimum influence of magnification errors because of the curved surface of the retina.