This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Ophthalmology
[{'content': 'Blow out fracture of orbit commonly produces \nSelect and explain. \nA. Deviation of septum, B. Retinal haemorrhage, C. Fracture of nasal bones, D. Fracture of floor of orbit', 'role': 'user'}, {'content': 'Answer: D \nExplanation: (D) Fracture of floor of orbit # Blow out fracture of orbit; Intraorbital haemorrhages, proptosis, paralysis of extrinsic muscles and fracture of the floor of the orbit are not infrequent following a blunt injury to the orbital region> Proptosis develops due to reactive oedema and intra-orbital haemorrhage.> Partial or complete ophthalmoplegia occurs as a result of injury to the muscles or due to profuse orbital oedema.> In the fracture of the floor of orbit, the eyeball is depressed into the maxillary antrum & the inferior rectus and inferior oblique muscles are entrapped causing diplopia.> There occurs limitation of upward gaze, and downward gaze may also be reduced because of the pinched inferior rectus muscle in between the chips of the broken bone> A positive forced duction test, downwards and inwards displacement of the globe and radiological evidence virtually confirm the diagnosis of blowout fracture with incarcerated orbital tissue.> The fracture of the base of skull implicates optic foramen and may cause optic atrophy or pulsating exophthalmos.> The fracture of the optic canal is characterised by a wound at the lateral part of the eyebrow, loss of direct homolateral pupillary reaction and hemianopic field defects.> The patient may suffer from epistaxis and varying periods of unconsciousness.> The pallor of the optic disc may be noticed 2-3 weeks after the injury. Serial radiological tomograms taken at one minute intervals may confirm the diagnosis.', 'role': 'assistant'}]