Citation: Daroff R (2005) Enophthalmos Is Not Present in Horner Syndrome. PLoS Med 2(4): e120. https://doi.org/10.1371/journal.pmed.0020120
Published: April 26, 2005
Copyright: © 2005 Robert Daroff. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Competing interests: The author has declared that no competing interests exist.
The case report by Nautiyal et al.  is an instructive reminder that the first episode of an acute painful Horner Syndrome should prompt imaging of the ipsilateral internal carotid artery, since carotid dissection (as well as other conditions, such as high-grade stenosis) needs to be ruled out. Unfortunately, the authors perpetuate the extremely common misconception that enophthalmos accompanies ptosis and miosis in human Horner Syndrome. It is only an illusion of enophthalmos caused by the ptosis. This is evident in the left eye of their patient in Figure 1 of the case report.
Actual measurement with exophthalmometry clearly demonstrates the lack of enophthalmos. As stated by Loewenfeld (, p. 1139), “Animals such as cats, rats, or dogs have enophthalmos on the side of the sympathetic lesion. But in man, the enophthalmos is only apparent. The small palpebral fissure makes the eye look sunken in on the affected side, but the position of the globe in the orbit remains virtually unchanged. This has been found by all workers who have measured the supposed enophthalmos objectively.” Loewenfeld cites four supportive references.
Thompson and Miller (, p. 964) provide four additional references that the enophthalmos “is apparent rather than real.”
- 1. Nautiyal A, Singh S, DiSalle M, O'Sullivan J (2005) Painful Horner syndrome as a harbinger of silent carotid dissection. PLoS Med 2: e19.
- 2. Loewenfeld IE (1999) The Pupil: Anatomy, physiology, and clinical applications, Volume 1. Boston: Butterworth-Heinemann. 2 v.
- 3. Thompson HS, Miller NR (1998) Disorders of pupillary function, accommodation, and lacrimation. In: Miller NR, Newman NJ, editors. Walsh and Hoyt's Clinical Neuro-ophthalmology. 1. Baltimore: Williams and Wilkins. pp. 961–1040. 5th ed.