Table 4. Indications for various chemotherapy methods for retinoblastoma.

Feature	Intravenous chemotherapy	Intra-arterial chemotherapy	Periocular chemotherapy	Intravitreal chemotherapy
Primary therapy
Bilateral retinoblastoma	+++	+	+	∼
Unilateral retinoblastoma	++	+++	+	∼
Secondary therapy for recurrent/persistent tumour
Retinoblastoma	++	+++	+	∼
Subretinal seeds	++	+++	+	∼
Vitreous seeds	++	++	+	+++

+++ marked, ++ intermediate, + minimal, ∼ little to none.

Subtenon's chemotherapy as primary therapy is used in conjunction with intravenous chemotherapy for groups D and E.

If intravenous chemotherapy is used as primary and secondary therapy, the regimen is changed to different agents in secondary therapy.