Systematic review and risk factor analysis of post-vitrectomy silicone oil migration to the central nervous system

Silicone oil (SiO) migration to the central nervous system (CNS) is a rare complication of SiO tamponade after vitreo-retinal surgeries, it could masquerade hemorrhage on computed tomography neuro-imaging. Only limited cases were reported in the literature, certain intra-operative and post-operative ocular risk factors might contribute to the different extend of SiO migration in the CNS.

To study the risk factors for cerebral ventricular migration (CVM) on top of visual pathway migration (VPM).

Conforming to the preferred reporting items for systematic reviews and meta-analyses guidelines, literature searches on PubMed, MEDLINE, EMBASE were performed on June 1, 2024. Publications on SiO migration to CNS were included in this review. Non-English articles, and studies without neuro-imaging of the CNS were excluded. Patient demographics, SiO filled eyes' ocular characteristics and vitrectomy surgical details were extracted from included studies in this review. VPM and CVM were assigned as group 1 and group 2 respectively. Fisher's exact tests, Mann-Whitney U tests and binary logistic regression were performed.

Total 68 articles were obtained after searches, 48 publications were included for analysis. Total 54 SiO filled eyes were analyzed. Post-vitrectomy intraocular pressure (IOP) was found to be significant in both Mann-Whitney U test (P = 0.047) and binary logistic regression (P = 0.012). Diabetic was found to be significant in binary logistic regression (P = 0.037), but at borderline risk for CVM in Fisher's exact test (P = 0.05). Other significant factors include longer SiO tamponade time (P = 0.002 in Fisher's exact test) and visual acuity (P = 0.011 in binary logistic regression). Optic nerve atrophy or disc cupping (P = 1.00, P = 0.790) and congenital optic disc anomalies (P = 0.424) were all with P > 0.05.

SiO migration to CNS is rare with limited case reports only. Our analysis of the existing literature demonstrated higher post-vitrectomy IOP was associated with CVM, followed by patients' diabetic status, longer SiO tamponade time and visual acuity. Optic nerve atrophy, disc cupping and congenital optic disc anomalies were not associated. Modifiable risk factors of post-vitrectomy IOP and SiO tamponade time should be closely monitored by vitreo-retinal surgeons. Lower IOP target post-vitrectomy and earlier SiO removal surgeries should be arranged.