Nyctalopia (Greek for "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). The most common cause of nyctalopia is
retinitis pigmentosa, a disorder in which the rod cells in the
retina gradually lose their ability to respond to the light.
Patients suffering from this genetic condition have progressive
nyctalopia and eventually their daytime vision may also be
affected. In X-linked congenital stationary night blindness,
from birth the rods either do not work at all, or work very
little, but the condition doesn't get worse. Another cause of
night blindness is a deficiency of retinol, or vitamin A, found
in fish oils, liver and dairy products. In the Second World War
misinformation was spread by the British to cover up the reason
for their pilots' successful night time missions. Their success
was, in the misinformat