This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
A child with a unilateral white reflex raised IOP. The required investigations are: 
Select and explain. 
A. USG, B. Observation under anesthesia, C. Tonometry, D. All
D: All
Answer: D: All 
Explanation: ALL Investigations for Leucocoria - Examination under anaesthesia X Ray-orbit, UltrasoundQ, CT scan to look for calcification size, and extent of tumor MRI to rule out ectopic intracranial retinoblastoma & optic nerve involvement. LDH level is raised in aqueous Measurement of IOP by Tonometry Distant metastasis is suspected by CSF examination (lumbar puncture), bone /liver/spleen scan, bone marrow aspiration biopsy etc