Nyctalopia (from
Greek νύκτ-,
nykt- "night"; αλαός,
alaos "blind, not seeing", and ὄψ,
ops "eye"), also called
night-blindness, is a condition making it difficult or impossible to see in relatively low light. It is a symptom of several eye diseases. Night blindness may exist from birth, or be caused by
injury or malnutrition (for example, a lack of
vitamin A). It can be described as insufficient
adaptation to darkness.