# Hippus

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Pupillary response

**Pupillary hippus**, also known as **pupillary athetosis**, is spasmodic, rhythmic, but regular dilating and contracting [pupillary movements](/source/Pupillary_response) between the [sphincter](/source/Sphincter) and [dilator](/source/Iris_dilator_muscle) [muscles](/source/Eye_muscles).[1][2] Pupillary hippus comes from the Greek *[hippos](https://en.wiktionary.org/wiki/%E1%BC%B5%CF%80%CF%80%CE%BF%CF%82#Ancient_Greek)* meaning horse, perhaps due to the rhythm of the contractions representing a galloping horse.[3] Notably, *hippos* in antiquity referred to involuntary eye movements which are nowadays called [nystagmus](/source/Nystagmus).[4]

It is particularly noticeable when [pupil](/source/Pupil) function is tested with a light,[2] but is independent of eye movements or changes in illumination.[1] It is usually normal, however pathological hippus can occur.[2][3]

Pathologic hippus, the phenomenon of increased oscillation or their amplitude, is associated with [aconite](/source/Aconitine) poisoning,[5] [altered mental status](/source/Altered_mental_status), trauma, cirrhosis, and [renal disease](/source/Renal_disease); suggesting a common pathway of [frontal lobe](/source/Frontal_lobe) dysfunction.[6] A retrospective study of 117 hospitalized patients with hippus noted an increased 30-day mortality when compared to controls and adjusted for other factors.[6]

## See also

- [Athetosis](/source/Athetosis)

- [Anisocoria](/source/Anisocoria) - condition characterized by an unequal size of the eyes' pupils.

## References

1. ^ [***a***](#cite_ref-McLaren_1-0) [***b***](#cite_ref-McLaren_1-1) McLaren J. W.; Erie J. C.; Brubaker R. F. (1992). "Computerized analysis of pupillograms in studies of alertness". *Investigative Ophthalmology and Visual Science*. **33**: 671–6.

1. ^ [***a***](#cite_ref-Cassin_2-0) [***b***](#cite_ref-Cassin_2-1) [***c***](#cite_ref-Cassin_2-2) Cassin, B. and Solomon, S. *Dictionary of Eye Terminology*. Gainesville, Florida: Triad Publishing Company, 1990.

1. ^ [***a***](#cite_ref-Beatty_3-0) [***b***](#cite_ref-Beatty_3-1) Beatty, J., & Lucero-Wagoner, B. (2000). The pupillary system. In J. T. Cacioppo, L. G. Tassinary & G. G. Bernston (Eds.), *The handbook of psychophysiology* (2nd ed.) (pp. 142-162). USA: Cambridge University Press.

1. **[^](#cite_ref-4)** Gerb, Johannes; Brandt, Thomas; Huppert, Doreen (July 2023). ["Historical descriptions of nystagmus and abnormal involuntary eye movements in various ancient cultures"](http://journals.sagepub.com/doi/10.1177/00368504231191986). *Science Progress*. **106** (3). [doi](/source/Doi_(identifier)):[10.1177/00368504231191986](https://doi.org/10.1177%2F00368504231191986). [ISSN](/source/ISSN_(identifier)) [0036-8504](https://search.worldcat.org/issn/0036-8504). [PMC](/source/PMC_(identifier)) [10469245](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10469245). [PMID](/source/PMID_(identifier)) [37642983](https://pubmed.ncbi.nlm.nih.gov/37642983).

1. **[^](#cite_ref-Reddy_5-0)** Forensic and State Medicine: Reddy

1. ^ [***a***](#cite_ref-Denny_6-0) [***b***](#cite_ref-Denny_6-1) Denny JC, Arndt FV, Dupont WD, Neilson EG (2008). "Increased hospital mortality in patients with bedside hippus". *Am J Med*. **121** (3): 239–45. [doi](/source/Doi_(identifier)):[10.1016/j.amjmed.2007.09.014](https://doi.org/10.1016%2Fj.amjmed.2007.09.014). [PMID](/source/PMID_(identifier)) [18328309](https://pubmed.ncbi.nlm.nih.gov/18328309).

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