forced duction test
The forced duction test separates a motility defect caused by mechanical restriction from one caused by a neurological lesion.1,2 Under topical anesthesia, the examiner grasps the eye with forceps and rotates it in the direction of reduced mobility.1 In children and uncooperative adults the test is done under general anesthesia before surgery.2
Checked movement of the globe makes the test positive and indicates a restrictive problem, while free movement points to a neurological lesion.1,3 For example, if an eye that cannot abduct moves freely into abduction with the forceps, the lateral rectus is paralyzed.2 Resistance instead points to contracture of the medial rectus, conjunctiva or Tenon's capsule, or to myositis of the medial rectus.2
More detail
With topical anesthesia, the patient looks at a hand held in the direction the forceps move the eye.2 Looking toward the hand keeps the patient's own innervation from resisting the passive movement and mimicking a restriction.2 Pressing the globe back into the orbit during the test can make a restricted eye test negative.2 The forced generation test is the companion maneuver, in which the patient tries to move the eye against a cotton-tip swab.3 Inability to push against the swab usually indicates weakness of the ocular motor nerve or muscle, and abnormal forced ductions with normal forced generations usually indicate a restrictive problem.3
Under general anesthesia, succinylcholine causes sustained contraction of the extraocular muscles for as long as 20 minutes and can confound the result, while a nondepolarizing muscle relaxant does not alter the test.4 Surgeons use the test at the beginning and end of each strabismus operation and at stages in between.4
Sources (8)
- Kanski, Clinical Ophthalmology (2024), ch. 4
- von Noorden and Campos, Binocular Vision and Ocular Motility, ch. 20
- Liu, Volpe and Galetta, Neuro-Ophthalmology: Diagnosis and Management, ch. 2
- von Noorden and Campos, Binocular Vision and Ocular Motility, ch. 26
- Rutstein, R., Daum, K. (1997). Anomalies of Binocular Vision: Diagnosis & Management, Mosby.
- Forced Duction Test: Is It Necessary after the Scleral Buckling Procedure? (2020). PMC, 7(7), 1-5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7383212/
- Forced Duction, Active Force Generation, and Saccadic Velocity Tests. (1978). PubMed, 786926. https://pubmed.ncbi.nlm.nih.gov/786926/
- Unmasking Bilateral Inferior Rectus Restriction in Thyroid Eye Disease: Using Degree of Cyclotropia. (2015). PubMed, 26564931. https://pubmed.ncbi.nlm.nih.gov/26564931/
Reviewed October 2026