Marcus Gunn phenomenon
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an increase in the width of the palpebral fissures during chewing, sometimes with a rhythmic elevation of the upper lid when the mouth is open and with ptosis when the mouth is closed.
Marcus Gunn pupilA change in the pupillary reflex, caused by unilateral optic nerve or retinal disease.
A light is shone, first on one eye and then the other, with the opposite eye covered; the affected eye demonstrates a slight contraction or dilation of the pupil.