Source : Webster's Revised Unabridged Dictionary (1913)

Ophthalmology \Oph`thal*mol"o*gy\, n. [Gr. ? the eye + -logy:
   cf. F. ophthalmologie.]
   The science which treats of the structure, functions, and
   diseases of the eye.

Source : WordNet®

ophthalmology
     n : the branch of medicine concerned with the eye and its
         diseases