A tadpole pupil (pictured above, right eye) occurs with segmental spasm of the iris dilator muscle producing episodic pupillary distortion, often in the shape of a tadpole. Dr. Stan Thompson of the University of Iowa, Department of ophthalmology, first coined this phenomenon as a "tadpole pupil" in 1983. This intermittent, irregular mydriasis usually lasts less than five minutes but has been described to last up to 15 minutes. It may occur several times per day, over several days to weeks. Tadpole pupil usually resolves without recurrence, but it does have a strong association with the subsequent development of a Horner's Syndrome. Tadpole pupil has also been associated with Adie tonic pupil and migraines. Hence, clinicians should consider additional workup for these entities.
- Balaggan KS, Hugkulstone CE, Bremner FD. Episodic segmental iris dilator muscle spasm: the tadpole-shaped pupil. Arch Ophthalmol. 2003;121(5):744-745.
- Thompson HS, Zackon DH, Czarnecki JS. Tadpole-shaped pupils caused by segmental spasm of the iris dilator muscle. Am J Ophthalmol. 1983;96(4):467-77.
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