Source : Webster's Revised Unabridged Dictionary (1913)

Asthenopia \As`the*no"pi*a\, n. [Gr. 'a priv. + sqe`nos strength
   + 'w`ps eye.]
   Weakness of sight. --Quain. -- {As`the*nop"ic}, a.

Source : WordNet®

asthenopia
     n : a tiredness of the eyes caused by prolonged close work by a
         person with an uncorrected vision problem [syn: {eyestrain}]