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Contractions of the iris dilator muscle, a smooth muscle of the eye running radially in the iris, [2] can cause irregular distortion of the pupil, thus making the pupil look tadpole shaped and giving this condition its name. Episodic segmental iris mydriasis was first described and termed “tadpole pupil” in 1912 by HS Thompson. [1]
Anisocoria has various causes: [3] Physiological anisocoria: About 20% of the population has a slight difference in pupil size, which is known as physiological anisocoria. In this condition, the difference between pupils is usually less than 1 mm. [4] Horner's syndrome
Dilation of the pupil in an eye with synechia can cause the pupil to take an irregular, non-circular shape (dyscoria) as shown in the photograph. If the pupil can be fully dilated during the treatment of iritis, the prognosis for recovery from synechia is good. This is a treatable status. To subdue inflammation, topical corticosteroids can be used.
Dyscoria, a potential cause of anisocoria, refers to an abnormal shape of the pupil which may be due to developmental and intrauterine anomalies. [4] [verification needed] If the abnormal eye remains dilated when shined with light, it is a pathological small pupil. [citation needed]
The effect of spherical aberration (a fourth-order aberration) increases as the fourth power of the pupil diameter. Doubling pupil diameter increases the spherical aberration component by a factor of 16. [7] Thus, a small change in pupil size can cause a significant change in spherical aberration.
The extraneous pupil is c. 2.5mm away from the principal pupil. In cases of true polycoria there is an intact sphincter muscle, which contracts and dilates the pupils. [7] In an eye without polycoria, the sphincter muscle is a part of the iris that functions to constrict and dilate the pupil.
Few people have spent time gazing into a sheep’s eyes, but if you have, you may have noticed something very strange about their pupils. Instead of being round, as is the case with humans, they ...
Both 0 and 180 degrees lie on a horizontal line at the level of the center of the pupil, and as seen by an observer, 0 lies on the right of both the eyes. [medical citation needed] Irregular astigmatism, which is often associated with prior ocular surgery or trauma, is also a common naturally occurring condition.