It is associated with lesions of the central nervous system, as may occur in head injury. Hutchinson's pupil A pupil that is dilated and completely inactive to all stimuli. It is slightly larger (,3%) than the real pupil and situated slightly behind it (Fig. P23).Įxit pupil of the eye This is the image of the iris aperture formed by the crystalline lens. It is some 13% larger than the real pupil and located slightly in front of it. It is what one sees when one looks at an eye. Pupil dilatation See mydriatic pupil light reflex.Įntrance pupil of the eye This is the image of the iris aperture formed by the cornea. Pupil constriction See miosis pupil light reflex. It is used in research but also as a clinical test. A circular aperture made in a diaphragm which can be mounted in front of the eye to provide a constant and smaller pupil size. See iridoplegia tabes dorsalis.Īrtificial pupil 1. The condition is bilateral, the pupils are small and usually unequal. It is most often noted in cases of severe optic nerve dysfunction or retinal disease.Īpparent pupil See entrance pupil of the eye.Īrgyll Robertson pupil Pupil that reacts when the eye accommodates and converges but fails to react directly and consensually to light. See efferent pupillary defect Adie's syndrome pupil light reflex.Īmaurotic pupil Miotic pupil that does not react to direct and consensual ipsilateral light stimulation, but does react consensually to contralateral stimulation. myotonic pupil pupillotonia tonic pupil (some authors use this last term when the cause is known and Adie's pupil when the cause is unidentified). Other causes include temporal arteritis in elderly patients, syphilis or diabetes. It may be due to a disease of, or injury to, the ciliary ganglion or to the short ciliary nerves. The condition is usually unilateral, with the affected pupil being the larger of the two (anisocoria). The reaction of the pupil to a near target is also delayed and slow. See acorea anisocoria corectopia dicoria dyscoria hippus iridectomy microcoria miosis dilator pupillae muscle sphincter pupillae muscle mydriasis Edinger-Westphal nucleus polycoria polyopia pupil light reflex.Īdie's pupil A pupil in which the reactions to light, direct or consensual, are almost abolished, with a reaction occurring only after prolonged exposure to light or dark. The function of the pupil is to regulate the amount of light admitted into the eye, to optimize the depth of focus and to mitigate ocular aberrations. Its diameter can vary from about 2 to 8 mm. It is located slightly nasally to the centre of the iris. Aperture within the iris, normally circular, through which light penetrates into the eye.
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