night blindness

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A condition of the eyes in which vision is normal in daylight or other strong light but is abnormally weak or completely lost at night or in dim light. The condition may result from vitamin A deficiency, disease, or hereditary factors. Also called nyctalopia.

Century Dictionary and Cyclopedia

1. n. Inability to see in a dim light; nyctalopia. Also called daysight. See nyctalopia and hemeralopia.

Wiktionary

1. n. The optic condition nyctalopia, the inability to see clearly in faint light, as at night

GNU Webster's 1913

1. n. (Med.) See Hemeralopia.

WordNet 3.0

1. n. inability to see clearly in dim light; due to a deficiency of vitamin A or to a retinal disorder