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the opening in the center of the iris through which light enters the eye; see also Plate 17.
Adie's pupil tonic pupil.
Argyll Robertson pupil one that is miotic and responds to accommodation effort, but not to light.
fixed pupil a pupil that does not react either to light or on convergence, or in accommodation.
Hutchinson's pupil one that is dilated while the other is not.
a stationary pupil unresponsive to all stimuli.
Etymology: L, figere, to fasten, pupilla, little girl
an abnormal condition in which the pupils fail to dilate or contract when stimulated. The cause is commonly adhesions binding the iris to the lens capsule or acute glaucoma causing interference with the nerve supply of the iris.
fix·ed pu·pil(fikst pyū'pil)
A stationary pupil unresponsive to all stimuli.
the aperture in the center of the iris which regulates the amount of light that reaches the retina.
dilated pupil due to parasympathetic denervation.
Argyll Robertson pupil
one that is miotic and responds to accommodation effort, but not to light.
a pupil that does not react either to light or on convergence, or in accommodation.
a congenital or acquired pupillary membrane that obstructs the pupil.
a complete posterior synechia that separates the anterior and posterior chambers of the anterior compartment.
spastic pupil syndrome
anisocoria with pupils that fail to dilate in darkness. Seen in cats infected with feline leukemia virus. The virus has been observed in the short ciliary nerves and ciliary ganglia of some affected cats.