Pediatric Patient Referred for an Optic Nerve Mass

A 13-year-old male patient was referred for evaluation of an optic nerve mass with decreased central vision and occasional pain. Examination revealed an afferent pupillary defect, a few vitreous cells, and an optic nerve lesion associated with a small peripapillary hemorrhage, peripapillary subretinal fluid, and scattered white lesions in the inferior retinal periphery. What would you do next?