<prompt> What is the length of optic nerve20 mm30 mm40 mm50 mm  <response>: Answer- D. 50 mmoptic nerve is about 47-50 mm in length and can be divided into 4 pas : -Intraocular pa 1 mmIntraorbital pa 30 mmIntracanalicular pa 5-9 mmIntracranial pa 10 mm 