Nyctalopia

As night blindness ( colloquially ), Latin Nyctalopia, in medicine hemeralopia the restriction of vision in dim light is called. The foreign words hemeralopia (from Greek ἡμέρα "day" and ὤψ " eye") and nyctalopia (from Greek νύξ "night" ), both ( paradoxically ) both for night blindness (ie Tagessichtigkeit ) as well as for day blindness (ie night vision ) are used and are to loud DIN 5340-207 no longer be used.

Night blindness is a partially - functional visual impairment.

The ability to adjust the eye ( adaptation) is to the darkness either restricted or completely failed.

Night blindness is caused by a malfunction or total loss of chopsticks. Traps the rods completely, it is called in the narrower sense of " night blindness ". The seeing at dusk is strongly hindered. In a nocturnal, unlit area seeing is virtually impossible.

It may be in the night blindness is a congenital defect or an acquired visual impairment. (Called " essential" ) Congenital forms are, for example, Oguchi syndrome ( mutation in the gene coding for S- arrestin gene) or the autosomal dominant type Nougaret. Acquired night blindness visual impairment, for example, caused by vitamin A deficiency or other disease of the eye.

In a vitamin A deficiency can in the rods is not enough rhodopsin ( visual purple ) are formed, which is formed from the vitamin A derivative retinal and opsin the protein.

In addition, night blindness may indicate the beginning of a retinitis pigmentosa.