Cyclotropia
A strabismus with eye torsion about the visual axis.
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Cyclotropia is a form of strabismus involving torsion of one or both eyes about the visual axis, causing the visual fields to appear tilted relative to each other. The latent form, cyclophoria, occurs only in the absence of appropriate visual stimuli; both are subsumed as cyclodeviation. This condition can result in double vision and head tilt, and its role in vision disorders is not always correctly identified.
Quick Facts
- Surgical threshold
- above 5 degrees
Facts from the source article.
Diagnosis
Cyclotropia is diagnosed through subjective and objective tests, both of which should be assessed before surgery. Subjective tests include the Maddox rod test, Bagolini striated lens test, phase difference haploscope of Aulhorn, and the Lancaster red-green test (LRGT), with the LRGT being the most complete. Objective evaluation of torsion is reliably performed via fundus photography using landmarks such as the fovea centralis and optic disc.
Treatment
Small amounts of torsion may be asymptomatic and not require correction, as the visual system can compensate through motor responses or brain signal processing; cyclotropia of vascular origin often improves spontaneously. Cyclotropia cannot be corrected with prism spectacles as other eye position disorders are, though two Dove prisms can rotate the visual field experimentally. For cyclodeviations above 5 degrees, surgery is normally recommended, which may involve correcting an associated vertical deviation, a Harada–Ito procedure, or another procedure to rotate the eye inwards or outwards. Cyclodeviations without vertical deviation can be difficult to manage surgically, as correction may introduce a vertical deviation.
More in Disorders of Ocular Muscles, Binocular Movement, Accommodation and Refraction
Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Cyclotropia (CC BY-SA 4.0).
- Word definitions: the Codexery glossary, each quoted from its Wikipedia article.
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