forced duction test

forced duction test

A test used in ophthalmology to assess whether eye elevation or movements of the inferior muscles of the eye are restricted as a result of an injury, e.g., of an orbital floor fracture. Used to determine if an ocular deviation is mechanically restricted versus paretic.
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Forced duction test preoperatively showed restriction in all directions and maximum in abduction.
Monocular elevation deficiency (MED) is classified as three subtypes: 1) restrictive form, with features including positive forced duction test (FDT) for elevation, normal elevation forced generation test (FGT), and elevation saccadic velocity, often an extra or deeper lower eyelid fold on attempted upgaze and poor or absent Bell phenomenon; 2) paretic form with elevator muscle weakness, with features including free FDT, reduced elevation FGT and saccadic velocity, in which the Bell phenomenon is often preserved; and 3) a combination form, with features including positive FDT for elevation and reduced FGT and saccadic velocity for elevation.
A forced duction test is performed at this point to confirm adequate relief of entrapment.
Diplopia occurs due to many factors which can be differentiated clinically or by forced duction test.
Mechanical entrapment of the orbital content most commonly the inferior rectus muscle followed by the inferior oblique muscle causes diplopia in up gaze and down gaze and the forced duction test in this case is positive.
Strabismus surgery was performed according to the results of forced duction test (FDT).
The forced duction test was positive for inferior rectus (IR) of the involved eye in 20 of the 36 eyes (55.
Treatment is generally based on carrying out the forced duction test (FDT).
Dutton (1991) mentioned that a positive forced duction test may be misleading as it does not always correlate with entrapment.
Three patients were unable or unwilling to have forced duction test pre and postop- eratively because they feared further manipulation of the injured eye.
Forced duction test preoperatively showed restriction in adduction and supraduction in both cases.
High myopia should be considered in the differential diagnosis such as the 6th nerve palsy excluded by Positive forced duction test, Thyroid eye disease excluded by Normal muscles on CT, Myasthenia Gravis excluded by a Normal tensilon test.