A distinction can be made between congenital and acquired night blindness. Night blindness means that from a certain drop in brightness – in contrast to healthy people – you can no longer see anything, i.e. you are blind. For those affected, only the outlines of objects are recognizable.
The main reason for night blindness is a congenital, hereditary inferiority of the rod apparatus, the so-called essential night blindness. The chopsticks work, but cannot adapt to lower lighting. Therefore, apart from the night vision problems, everything else is normal here, including visual acuity, field of vision and color vision. Other causes are vitamin A deficiency due to insufficient intake or use in gastrointestinal diseases and liver disorders.
Vitamin A is necessary for the regeneration of visual purple and without it, dark adaptation is not possible. In contrast to congenital night blindness, this form can be remedied by taking the vitamin with food. Also acquired disturbances of rod function through diseases of the retina and the optic nerve. The best known is retinitis pigmentosa. In fact, whenever large parts of the outer retina are destroyed – this is where most of the rods are located – problems arise. Last but not least, significant clouding of the cornea and the lens of the eye leads to a strong attenuation of light and thus, of course, to limited vision in the dark. But this is not true night blindness.
The diagnosis of night blindness is based on the doctor-patient conversation and with the help of special devices, the so-called nyctometers or mesoptometers.
Therapeutic options and the prognosis for night blindness are limited and largely dependent on the underlying cause. Only if you can treat the underlying disease in acquired night blindness in time can its development be stopped. In the case of congenital night blindness or retinitis pigmentosa, which has not yet been cured, one can only provide help with protective goggles. It is also not possible to prevent night blindness, since in most cases it is a congenital or acquired disease.
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