Night blindness

Synonyms in a broader sense

Medical: hemeralopia
English: night blindness
Extended: Blindness, problems driving at night


Night blindness is a disturbed ability of the eyes to adapt to darkness. For those affected, only outlines can be seen.
The eyes adapt to light very quickly, while adapting to darkness takes a very long time at 30 to 50 minutes.


People whose eyes cannot adapt well to the darkness are called night blind. Such a real night blindness, which rarely occurs, is usually innate.
It can also be acquired due to a vitamin A deficiency. In those affected, the rods (sensory cells of the retina, which are responsible for black and white vision) are impaired in their function. The patients see very little at night or at dusk. You only see outlines. At the ophthalmologist (specialist in ophthalmology) night blindness is measured and recognized using devices.
There is no therapy.


Night blindness can be acquired or in most cases congenital. Acquired night blindness is due to the poor functioning of certain sensory cells in the retina of the eye.
The human retina is made up of many different types of cells. Two of them are the chopsticks and cones. Both have the task of converting incident light into electrical signals and transmitting them to the brain. Cones are responsible for color vision, whereas rods are responsible for black and white vision, i.e. for light and dark - especially at night. In the night blind, these rods are only weakly functional and this is where blindness comes from. Only the rods work in the dark - there are no colors in the dark ("At night all cats are grey."). If these fail, the patients are almost blind.
Night blindness can also be acquired, which is very rare these days, as there must be a vitamin A deficiency. A vitamin A deficiency can either be caused by insufficient intake or by non-usability.
Night blindness can also occur with various underlying diseases. For example, in the case of changes in the retina that are caused by the breakdown of the receptors.
In the so-called "Retinopathia pigmentosa“Above all, the chopsticks are destroyed. The patients notice the night blindness early on. The vision of colors is usually not particularly impaired in these patients. Patients can see well even in daylight. As soon as the light becomes weaker and mainly the receptors for chiaroscuro or black and white have to work, the disease becomes noticeable.


A Night blindness makes itself noticeable by the fact that it is very difficult for the eyes to adapt to their surroundings in twilight and darkness. The patient's view is very limited.
The Visual acuity however, brightness is not affected. In the Retinopathia pigmentosa are the chopsticks that are used for the See are responsible at night, destroyed. If the light is too low, there is complete blindness.


The Night blindness is at the ophthalmologist (specialist in ophthalmology) means Testing proven. First and foremost, however, conversations between doctor and patient are informative.
There are devices like that Nyctometer or Mesoptometer for use.These measure the twilight visual acuity. They check the performance of the visual organ between daytime vision and the like. complete adaptation to darkness.
The patients are first exposed to very bright light, after which they have to move to the darkest possible room. After a period of about 15 minutes getting used to it, the patient is presented with different optotypes in different lighting conditions.


The innate Night blindness cannot be treated. It is inherited and always progresses.
The advance of the so-called Retinopathia pigmentosa can be slowed down slightly by the administration of vitamin A according to studies.
You should also pay attention to other eye diseases. Maybe there is also one cataract (cataract) in front of who the Eyesight also deteriorated. If there is acquired night blindness, vitamin A can also be substituted.
Basically, it should be noted that patients no longer drive a car at dusk.


In the innate Night blindness the finding remains for a lifetime. An improvement in symptoms through therapy is not to be brought about. People have to come to terms with their illness. The disease can move into other stages and into further ones degenerative diseases develop.


Of the Night blindness cannot be prevented because in most cases it is a congenital disease. However, it should always be balanced nutrition be taken care of in order to prevent the development of night blindness.
Vitamin A and its precursors are found in the following foods, among others:

  • Carrots
  • liver
  • egg yolk
  • Butter.

Additional information

  • Color blindness
  • Red-green blindness
  • Blindness
  • Visual center

You can find all information about ophthalmology at: Ophthalmology A-Z