aniseikonia

noun

an·​is·​ei·​ko·​nia ˌa-ˌnī-ˌsī-ˈkō-nē-ə 

: a defect of binocular vision in which the two retinal images of an object differ in size

aniseikonic

ˌa-ˌnī-ˌsī-ˈkä-nik 

adjective

Word History

Etymology

anis- + Greek eikṓn "image" + -ia entry 1 — more at icon

Note: The American ophthalmologist Walter B. Lancaster (1863-1951) took credit for coining the word in an article "Aniseikonia" published jointly in the Transactions of the American Ophthalmological Society (vol. 36 [1938], pp. 227-34) and Archives of Ophthalmology (vol. 20 [1938], pp. 907-12). Though recent sources claim that he originated the word in 1932 (as Eleanore Z. Thill, "Theory and practice of spectacle correction of aniseikonia," vol. 1, chapter 47 of Duane's Ophthalmology on CD-ROM, 2006 edition), there appears to be no evidence of this contemporary with Lancaster's publications or his professional activity in the 1930's. The usual Latinization of medical terms formed from Greek elements would have resulted in anisiconia, but the coiner chose a direct transliteration from Greek.

First Known Use

1934, in the meaning defined above

Medical Definition

aniseikonia

noun

an·​is·​ei·​ko·​nia ˌan-ˌī-ˌsī-ˈkō-nē-ə 

: a defect of binocular vision in which the two retinal images of an object differ in size

aniseikonic

-ˈkän-ik 

adjective