Background Intravitreal injection therapy (IViT) for retinoblastoma has shown promise in the treatment of vitreous seeds; however, the potential for tumour dissemination following intravitreal penetration has limited its use. This review evaluates the risk of extraocular tumour spread in patients receiving therapeutic intravitreal injections for retinoblastoma.

Methods PUBMED (1946–present), SCOPUS (all years), Science Citation Index (1900–present) and Conference Proceedings Citation Index—Science (1990–present) electronic databases were searched to identify all published reports of IViT for retinoblastoma in humans.

Results 14 studies with original IViT data were included in this review. A total of 1304 intravitreal injections were given in 315 eyes of 304 patients, with one report of extraocular tumour spread and one patient in whom intravitreal treatment could not be excluded as a contributor to metastatic disease. The proportion of subjects with extraocular tumour spread potentially due to IViT in these combined reports was 0.007 (95% CI 0.0008 to 0.0236), with a mean follow-up of 72.1 months. In a subset of 61 patients receiving IViT via safety enhancing injection techniques (347 injections, 19.6 months mean follow-up), there were no reports of tumour spread.

Conclusions Local and systemic tumour spread following IViT in cases of retinoblastoma is rare, and this risk is potentially reduced by the use of safety enhancing injection techniques. These results suggest that the risk of tumour spread should not preclude IViT use for carefully selected patients as part of multi-modal globe salvaging therapy.