The Collaborative International Dictionary of English v.0.48:

Hemeralopia \Hem`e*ra*lo"pi*a\, n. [NL., fr. Gr. ?, the opposite
   of ?; ? day + ? of ?. See Nyctalopia.] (Med.)
   A disease of the eyes, in consequence of which a person can
   see clearly or without pain only by daylight or a strong
   artificial light; day sight.
   [1913 Webster]

   Note: Some writers (as Quain) use the word in the opposite
         sense, i. e., day blindness. See Nyctalopia.
         [1913 Webster]

WordNet (r) 3.0 (2006):

hemeralopia
    n 1: inability to see clearly in bright light [syn:
         hemeralopia, day blindness]