Retinal artery/arteriole occlusion risks after endovascular treatment for unruptured intracranial aneurysm

Background To evaluate the association between retinal artery/arteriole occlusion (RAO) and unruptured intracranial aneurysm (UIA).Methods Incident UIA patients from a nationwide cohort (n=253 240) were categorised into three groups based on subsequent treatment: observation (n=208 993), microsurgical clipping (n=14 168) and endovascular treatment (EVT) groups (n=30 079). The incidence and the incident time of RAO were analysed. HRs of RAO and associated risk factors were evaluated. Additionally, a hospital cohort comprising 2569 consecutive UIA patients treated at a tertiary hospital was analysed with detailed clinical information of UIAs.Results In the nationwide cohort analysis, the incidence of RAO was significantly higher in EVT group than in observation and clipping groups, especially within 60 days (early RAO (within 60 days): HR=4.00, 95% CI: 2.44 to 6.56); delayed RAO (after 60 days): HR=1.74, 95% CI: 1.13 to 2.68). Multivariable analysis showed that the presence of chronic kidney disease (p=0.009) and use of a balloon microcatheter during the procedure (p=0.013) were associated with a higher risk of RAO. In hospital cohort analysis, 11 (0.8%) cases of RAO occurred after EVT, whereas none occurred after microsurgical clipping (p<0.001). Patients with RAO were younger and received balloon microcatheters more frequently than their counterparts. Ten cases of RAO (90.9%) occurred in paraclinoid aneurysms, where EVT was preferred over microsurgical clipping.Conclusions Performing EVT for UIA may increase the risk of subsequent RAO. Care should be taken when treating paraclinoid aneurysms with balloon microcatheters.