pseudostrabismus
Pseudostrabismus is the clinical impression of a misaligned eye when no strabismus is present.1 The illusion is common in young children, and roughly half of the young children sent to ophthalmologists for esotropia turn out to have pseudostrabismus.3
Prominent epicanthal folds are a common cause.2 The fold obscures the inner canthus and makes the eyes look crossed, especially in side gaze, where the adducted eye is buried under the skin fold.2,3 A wide, flat nasal bridge adds to the effect.3 An unusually short interpupillary distance can likewise simulate esotropia, and a wide one can simulate exotropia.1,2
Angle kappa can also produce pseudostrabismus.1,2 The fovea normally lies temporal to the anatomical center of the posterior pole. As a result, the corneal light reflex sits slightly nasal to the center of the cornea in each eye, a positive angle kappa.1,2 A large positive angle kappa, as with a macula dragged temporally in retinopathy of prematurity, simulates exotropia.1,2 A negative angle kappa, as in high myopia, places the reflex temporally and simulates esotropia.1,2
More detail
The examiner can show anxious parents that the deviation disappears when the skin of the nasal bridge is lifted, and centered corneal light reflexes demonstrate the alignment.2,3 The epicanthal fold normally fades as the bridge of the nose develops.2 Flat nasal bridges and wide epicanthal folds are more common in Asian children, and one study found that a referral for infantile esotropia proved correct in only 5.9% of children of Chinese descent, against 36% of other children.3
Facial asymmetry can create the impression of a hypertropia that further examination does not confirm.2 Angle kappa also distorts real deviations. A large positive angle kappa makes an existing exodeviation look worse than it is and can mask part of an esodeviation.2
Sources (8)
- Kanski, Clinical Ophthalmology (2024), ch. 18
- von Noorden and Campos, Binocular Vision and Ocular Motility, ch. 12
- Yanoff and Duker, Ophthalmology (2023), ch. 11
- American Academy of Ophthalmology. 2020. Strabismus Terminology. [online] Available at: <https://www.aao.org/education/bcscsnippetdetail.aspx?id=ce9b9c03-0bc8-4a63-8e51-09334c399fd7> [Accessed 6 May 2024].
- Noorden, G.K. and Campos, E.C. 2002. Binocular vision and ocular motility: theory and management of strabismus. 6th ed. St. Louis: Mosby.
- Rutstein, R. and Daum, K. 1997. Anomalies of Binocular Vision: Diagnosis & Management. St. Louis: Mosby.
- Von Noorden, G.K. and Campos, E.C. 2002. Binocular vision and ocular motility: theory and management of strabismus. 6th ed. St. Louis: Mosby.
- Xu, T.T., Bothun, C.E., Hendricks, T.M., Mansukhani, S.A., Bothun, E.D., Hodge, D.O. and Mohney, B.G. 2020. Pseudostrabismus in the First Year of Life and the Subsequent Diagnosis of Strabismus. Journal of Pediatric Ophthalmology and Strabismus, 57(3), pp.154-159.
Reviewed October 2026