c.1200, from Old English ege (Mercian), eage (West Saxon), from Proto-Germanic *augon (cf. Old Saxon aga, Old Frisian age, Old Norse auga, Swedish öga, Danish øie, Middle Dutch oghe, Dutch oog, Old High German ouga, German Auge, Gothic augo "eye"), from PIE *okw- "to see" (cf. Sanskrit akshi "the eye, the number two," Greek opsis "a sight," Old Church Slavonic oko, Lithuanian akis, Latin oculus, Greek okkos, Tocharian ak, ek, Armenian akn).
Until late 14c. the plural was in -an, hence modern dialectal plural een, ene. The eye of a needle was in Old English; to see eye to eye is from Isa. lii:8. Eye contact attested by 1965. Eye-opener "anything that informs and enlightens" is from 1863. Have an eye on "keep under supervision" is attested from early 15c.