Source : Webster's Revised Unabridged Dictionary (1913)

Emmetropia \Em`me*tro"pi*a\, n. [NL., fr. Gr. ? in measure,
   proportioned, suitable (? in + ? measure) + ?, ?, eye.]
   (Med.)
   That refractive condition of the eye in which the rays of
   light are all brought accurately and without undue effort to
   a focus upon the retina; -- opposed to hypermetropia, myopia,
   an astigmatism.

Source : WordNet®

emmetropia
     n : (ophthalmology) the normal refractive condition of the eye
         in which there is clear focus of light on the retina