Regional-specific retinal ischaemic index guided by ultra-widefield fluorescein angiography correlates with macular oedema in retinal vein occlusion

Aims To quantify the regional ischaemic index (ISI) in eyes with retinal vein occlusion (RVO) and to determine its correlation with macular oedema (ME). Methods In this retrospective study, ultra-widefield fluorescein angiography was performed in 46 eyes with RVO. The retinal ISI was calculated for the perimacular area (PMA), near-peripheral area (NPA), mid-peripheral area (MPA), and far-peripheral area (FPA), each further divided into superior-inferior and nasal-temporal segments. Central macular thickness (CMT) was measured with spectral-domain optical coherence tomography. Associations between regional ISI and CMT were analysed using Spearman’s correlation and linear regression. Results 46 eyes of 46 RVO patients were enrolled. Mean CMT was 453.73±301.48 µm. ISI in the S-NPA (superior NPA) strongly correlated with that in the I-NPA (inferior NPA) (r=0.53, p<0.001); a moderate correlation was observed between S-MPA (superior MPA) and I-MPA (inferior MPA) (r=0.32, p=0.03). Linear regression showed that S-NPA ISI predicted I-NPA ISI (B=0.54, p<0.001) and S-MPA ISI predicted I-MPA ISI (B=0.42, p=0.004). Among regions, PMA (r=0.31, p=0.04), I-NPA (r=0.35, p=0.02) and I-FPA (inferior FPA) (r=0.33, p=0.048) significantly correlated with CMT. Linear regression identified that PMA ISI (B=0.32, p=0.03) and I-NPA ISI (B=0.42, p=0.007) could independently predict increased CMT. Conclusions ME severity in RVO was correlated with PMA and I-NPA ischaemia. Moreover, these specific regional ISI values could independently predict CMT, highlighting potential targets for personalised therapy.