abduction
Abduction is the rotation of one eye in the temporal direction.1,2 Abduction is a duction, meaning a movement of one eye, and is usually tested with the fellow eye covered.2 In full, normal abduction the temporal limbus reaches the lateral canthus.2
The lateral rectus muscle abducts the eye, and the abducens nerve (cranial nerve VI) supplies the lateral rectus.3 The medial rectus, supplied by the oculomotor nerve (cranial nerve III), produces the opposite movement, adduction.3
More detail
Ductions can be graded at the bedside with a pen torch while the fellow eye is covered.4 Full movement scores 0, and increasing underaction scores −1 to −4.4 For the lateral rectus, −4 means the eye cannot abduct past the midline, −3 means it cannot abduct more than 22.5° past the midline, −2 means no more than 45°, and −1 means no more than 67.5°.4 Overactions are graded from +1 to +4 in the same way.4
Sources (8)
- Pickwell's Binocular Vision Anomalies, Appendices (glossary)
- Yanoff and Duker, Ophthalmology (2023), ch. 11
- Liu, Volpe and Galetta, Neuro-Ophthalmology: Diagnosis and Management, ch. 15
- Kanski, Clinical Ophthalmology (2024), ch. 18
- Rutstein, R., Daum, K. (1997). Anomalies of Binocular Vision: Diagnosis & Management, Mosby.
- Gunton, K. B. (2015). Dissociated vertical deviation: clinical features, associated abnormalities, and a new pathogenetic concept. Eye, 29(2), 213-220.
- Riordan-Eva, P., & Whitcher, J. P. (2008). Vaughan & Asbury's general ophthalmology. McGraw-Hill Medical Pub.
- Kushner, B. J. (2017). Diagnosis and treatment of diplopia. In Pediatric Ophthalmology and Strabismus (pp. 1023-1046). Springer, Berlin, Heidelberg.
Reviewed October 2026