Intravitreal Melphalan versus Topotecan for Vitreous Seeds in Retinoblastoma: A Comparative study of 64 Asian Indian eyes.

Purpose: To compare the outcomes of intravitreal melphalan (IVit-M) versus intravitreal topotecan (IVit-T) for vitreous seeds (VS) in retinoblastoma (RB).

Study design: Retrospective interventional study.

Participants: Patients of RB with VS receiving intravitreal chemotherapy between December 2012 and December 2022, at a single quaternary ocular oncology referral center.

Intervention: IVit-M injection of 25mcg/0.1cc in 25 eyes and IVit-T. of 30mcg/0.15cc in 39 eyes.

Outcomes: Resolution of VS, globe salvage, intravitreal chemotherapy-related complications RESULTS: The mean age at presentation was 28 months (median, 24 months; range, 4 to 144 months) for the IVit-M group and 25 months (median, 24 months; range, 2 to 60 months) for the IVit-T group. At the time of initiation of intravitreal injection, the VS belonged to type 1 (1 (4%) vs. 1 (3%)), type 2 (9 (36%) vs. 14 (36%)), type 3 (8 (32%) vs.18 (46%)), or a combination of these (7 (28%) vs. 6 (15%)) in IVit-M and IVit-T groups, respectively. Complete resolution of VS following intravitreal chemotherapy was seen in 22 (92%) and 28 (72%) eyes (p=0.069) in IVit-M and IVit-T groups, respectively. At a mean follow-up period of 44 months after the first IVit-C injection in the IVit-M group and 19 months in the IVit-T group, globe salvage was higher in the IVit-T group (77%) than in the IVit-M group (60%, p=0.148), respectively. Posterior segment complications were significantly higher in the IVit-M group than in the IVit-T group (p<0.001). These included retinal pigment epithelial atrophy (p<0.001), optic atrophy (p<0.001), vascular attenuation (p<0.001), and retinal/ subretinal hemorrhages (p=0.004).

Conclusion: IVit-T is as efficacious as IVit-M for controlling VS in RB, with a better safety profile in pigmented Asian Indian eyes.