Gunn crossing sign
1. compression of the underlying vein at arteriovenous crossings seen ophthalmoscopically in arteriolar sclerosis; Synonym(s): Gunn crossing sign
2. on alternate stimulation with light, the pupil of an eye with optic nerve transmission defect constricts poorly or even dilates when stimulated (a relative afferent pupillary defect).
Synonym(s): Marcus Gunn sign
Gunn cross·ing sign(gŭn kraws'ing sīn)
Retinal arteriovenous crossing with venous compression in hypertensive disease.