Wide-field swept-source OCT angiography of the periarterial capillary-free zone before and after anti-VEGF therapy for branch retinal vein occlusion

Abstract

Background The aim of the study was to investigate the changes in the periarterial capillary-free zone (paCFZ) after anti-vascular endothelial growth factor (VEGF) therapy in patients with branch retinal vein occlusion (BRVO) by wide-field swept-source optical coherence tomography angiography (SS-OCTA) and assess their associations with clinical outcomes. Methods In this retrospective observational study of 54 treatment-naïve BRVO patients with macular edema, we reviewed the findings of 12 × 12 mm2 SS-OCTA at baseline, 3, 6, and 12 months after intravitreal ranibizumab injections. The paCFZ and major retinal artery areas were measured on SS-OCTA images. The paCFZ area to artery area (P/A) ratio was calculated. Results The paCFZ areas and P/A ratios of first- and second-order arteries were significantly greater in BRVO eyes than in contralateral eyes (all P < 0.01), but there were no differences in the first- and second-order artery areas (P = 0.20 and 0.25, respectively). The paCFZ areas and P/A ratios decreased significantly at 3, 6, and 12 months after anti-VEGF therapy (all P < 0.01). The baseline P/A ratio was significantly correlated with the baseline best-corrected visual acuity (BCVA), central retinal thickness, and their improvements at 3, 6, and 12 months (all P < 0.05). Baseline BCVA and P/A ratios of first- and second-order arteries were independently associated with the final BCVA in multivariate linear regression. Conclusions Wide-field SS-OCTA shows that anti-VEGF therapy can lead to a significant improvement in the paCFZ parameters in BRVO. Smaller baseline P/A ratios on SS-OCTA tend to predict better visual outcomes at 12 months after anti-VEGF therapy.

Deep learning for artery–vein classification in optical coherence tomography angiography

“…The use of biomarkers such as the capillary-free zone to manually delineate the arteries and veins may be altered in the disease state, decreasing its reliability. 35 Therefore, future research should explore reliable quantitative methods for manual AV classification, such as using vessel tracking in fundus-guided or OCT-guided AV classification. 8,36…”

Imaging in retinal vascular disease: A review

“…Likewise, enlarged paCFZ can be found along unaffected major retinal arteries in eyes with BRVO 57 . Thus, paCFZ might be a useful biomarker for monitoring retinal diseases associated with change in retinal microvasculature 54 . Perivenous retinal whitening may be another related finding in RVO.…”

“…The paCFZ, first described by His in 1880, is a physiological avascular zone surrounding the retinal arteries mainly in the SCP and derives from a higher oxygen concentration in this area during embryonic development. 54 Vasoobliteration of the periarterial capillaries can be induced upon exposure to hyperoxia. 55 Arthur et al described a larger paCFZ in patients with DR imaged with OCT-A.…”

“…57 Thus, paCFZ might be a useful biomarker for monitoring retinal diseases associated with change in retinal microvasculature. 54 Perivenous retinal whitening may be another related finding in RVO. It occurs secondary to hypoperfusion induced middle retinal ischemia and can be best visualised with en-face OCT scans.…”

“…The periarterial capillary‐free zone (paCFZ) could be of additional special interest. The paCFZ, first described by His in 1880, is a physiological avascular zone surrounding the retinal arteries mainly in the SCP and derives from a higher oxygen concentration in this area during embryonic development 54 . Vasoobliteration of the periarterial capillaries can be induced upon exposure to hyperoxia 55 .…”