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Failure or imperfection of vision at night or in dim light, with good vision only on bright days. (Dorland, 27th ed)

The faculty of seeing during the night, with privation of the faculty during the day. It affects both eyes at once, when idiopathic. Its duration is uncertain, and treatment very obscure. It is, however, a disease of nervous irritability, and one of excitement of the visual nerve in particular. The indications of cure will consequently be-to allay direct irritation in every way; to excite counter-irritation by blisters; and to gradually accustom the eye to the impression of light. One labouring under this affection is called a Nyctalope, Nyctalops, Nyctalopex. Nyctalopia has also been used for night blindness. See Hemeralopia.

Night-blindness (less correctly, day-blindness; hemeralopia).

Night-blindness; sometimes used in a reverse sense, the patient seeing better in an obscure light than in bright sunlight. [Gr.]