Forced duction test is to find out-

Forced duction test (FDT) is performed to differentiate between the incomitant squint due to paralysis of extraocular muscle and due to mechanical restriction of the ocular movements. FDT is positive in case of incomitant squint and negative in extraocular muscle palsy Ref ; A.K.Khurana ; 6 th edition; page no: 357