Retinoblastoma: Intravitreal Chemotherapy

Vitreous seeding in retinoblastoma was long recognized as a major risk factor for eye survival due to the hypoxic environment of the vitreous and the reduced vitreous concentration of the drugs when delivered intravenously, intra-arterially and/or peri-ocularly. In 2012, the establishment of a safe technique for intravitreal melphalan injection helped to overcome this problem, and it became rapidly adopted worldwide. So, where do we stand now? First, recent studies have now confirmed long-term intravitreal chemotherapy (IVitC) safety and efficacy, not only for both persistent and recurrent vitreous and/or retrohyaloid disease but also against epi-retinal and epi-papillary gravitational implantation of seeds. On the other hand, clinical observations and a better knowledge of the cellular composition of the seeding helped us to re-evaluate the treatment eligibility criteria and response, as well as to redefine the treatment intensity according to the seed classification. Finally, as more advanced eyes are now salvaged, increasing efforts are made to control or minimize intraocular treatment-related toxicity and preserve vision. An increasing body of evidence has recently emerged suggesting that topotecan as monotherapy may supplant melphalan for vitreous disease without retinal toxicity, even at high doses. Last but not least, the advent of IVitC had a positive impact on the quality of life of the patients by significantly reducing the enucleation rate and eradicating the need for external beam irradiation.