- Group 2b (invasion of the cut end of the optic nerve): Patients receive carboplatin IV over 1 hour, vincristine IV, and etoposide IV over 4 hours on day 1, and, if necessary, intrathecal cytarabine on day 2. Treatment repeats every 21 days for 6 courses. Patients also undergo orbital radiotherapy 5 days a week for 4 weeks.