A 3-year-old girl from rural Uttar Pradesh presents with her mother who reports progressive vision loss over 2 weeks, particularly at night. On examination, the child has conjunctival xerosis with Bitot's spots bilaterally, corneal haze, and inability to see in dim light. She has a history of measles 3 months ago and poor dietary intake of leafy vegetables and eggs. Visual acuity is 6/18 in both eyes. What is the most appropriate immediate management?