A 2-year-old boy from rural Maharashtra is brought to the eye clinic by his mother with a chief complaint of white pupillary reflex (leukocoria) in the left eye for 3 months. On examination, the child is cooperative and visual acuity cannot be formally assessed. Dilated fundoscopy reveals a white intraocular mass arising from the retina with areas of calcification and vitreous haze. B-scan ultrasonography confirms a retinal mass with high internal reflectivity. The right eye appears normal on examination. There is no family history of retinoblastoma or other malignancies. What is the most appropriate next step in management?