| entrance pupil | <microscopy> The apparent size of the limiting aperture of a lens or lens system (properly that of the diaphragm), as seen from the object plane. This can shift and become a complex matter in some circumstances. In a properly set up microscope system it should be that of the substage iris diaphragm. (05 Aug 1998) |
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| exclusion of pupil | The condition resulting from posterior annular synechia, in which the iris is bound down throughout the entire pupillary margin, but the pupil is not occluded. Synonym: exclusion of pupil. (05 Mar 2000) |
| exit pupil | <microscopy> The exit pupil of a lens system is an image of the entrance pupil (hence conjugate to it) and normally should be the image of the limiting diaphragm. In both the microscope and the telescope it is the eyepoint where the beam has its smallest cross-section. It is also called the Ramsden circle or eyepoint. (05 Aug 1998) |
| eye-closure pupil reaction | A constriction of both pupils when an effort is made to close eyelids forcibly held apart. A variant of the pupil response to near vision. Synonym: Galassi's pupillary phenomenon, Gifford's reflex, lid-closure reaction, orbicularis phenomenon, orbicularis pupillary reflex, Piltz sign, Westphal's pupillary reflex, Westphal-Piltz phenomenon. (05 Mar 2000) |
| keyhole pupil | A pupil with a coloboma. (05 Mar 2000) |
| fixed pupil | A stationary pupil unresponsive to all stimuli. (05 Mar 2000) |