This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ocular motility and squint, Subject name: Ophthalmology
[{'content': 'Forced duction test is to find out \nSelect and explain. \nA. Ocular muscle palsy, B. Ocular muscle spasm, C. Angle of detion, D. Refractive error', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (Refer: AK Khurana Comprehensive Ophthalmology, 6th edition, pg no. 353 - 354) Forced duction testIt is performed to differentiate between the incomitant squint due to paralysis of extraocular muscle and that due to the mechanical restriction of the ocular movements.FDT is positive (resistance encountered during passive rotation) in cases of incomitant squint due to mechanical restriction and negative in cases of extraocular muscle palsy.', 'role': 'assistant'}]