Night blindness - causes and signs of night blindness

Today, there are three main types of hemeralopia. Among them:

• congenital (inherited and most often manifests itself at an early age);
• symptomatic (the result of deviations accompanied by damage to the retina);
• essential hemeralopia (as a consequence of functional changes in the retina due to a lack of essential vitamins in the body).

Causes

The retina consists of rods and cones, the former are responsible for the direct perception of light, and the latter for the perception of color. When the necessary balance between them is disturbed for some reason, hemeralopia occurs. The physiological mechanism for the progression of this condition is a significant decrease in the number and qualitative changes in the structure of the rods. The deviation may appear due to a failure in the metabolism of rhodopsin, a visual pigment that plays an important role in the process of perceiving surrounding objects in dim light.

Each of the three types of this disease is caused by different conditions. Congenital hemeralopia is exclusively hereditary, develops under the influence of genetic factors and is not eliminated by treatment. Essential hemeralopia is the most common in medical practice and is most often the result of improper nutrition and an inadequate diet. Symptomatic hemeralopia may occur against the background of other pathologies of the eye membranes, myopia, myopia, glaucoma, optic nerve atrophy and other diseases.

There are factors that create a favorable environment for the progression of such a deviation. For example:

• poor sleep (lack of sleep or insomnia);
• infections;
• long-term nervous and physical stress;
• lack of vitamin A in the body (usually manifested by an exacerbation in early spring);
• alcohol addiction and smoking.

Symptoms

There is a weakening of vision and spatial orientation in the twilight, a decrease in light sensitivity, a disruption of the dark adaptation process, a change in the electroretinogram, a narrowing of the visual field, primarily in colors. The fundus is usually unchanged. Sometimes, especially with congenital hemeralopia, light spots and focal pigmentation of the fundus are observed, caused by degenerative changes in the retina.

With symptomatic hemeralopia, the clinical picture of the underlying disease is observed.

Essential hemeralopia is often accompanied by conjunctival xerosis and other manifestations of vitamin A deficiency.

It received its popular name "night blindness" due to the main symptom by analogy with the peculiarity of chicken vision: these birds are diurnal and see almost nothing at dusk, so farmers have to leave the light near the drinker and feeder at night.

Diagnostics

An ophthalmologist deals with problems with hemeralopia, and you should contact him if you suspect it. A specialist will be able to make such a diagnosis based on the anamnesis data and a general examination of the patient's eye condition. It may be necessary to conduct a diagnostic study such as electroretinography.

Treatment

The congenital form is almost impossible to eliminate, but other types can be cured. Thus, in the case of the symptomatic variety, it can be eliminated by treating the underlying disease, which resulted in this blindness.

As for the essential type, the basis of treatment is diet. The lack of vitamins that provoked hemeralopia is replenished with an appropriate balanced diet.

Prevention

A set of preventive measures includes the need for timely treatment of eye abnormalities and a balanced diet. It is important to adhere to the work and rest regime for people who spend a lot of time at the computer. In no case should you work at a computer in poor lighting. If you sit in front of a monitor for a long time, you should give your eyes a rest every 40 minutes of your working time. When relaxing in the mountains in winter in bright sunlight, you should use sunglasses with an ultraviolet filter.

In order to read normally, we must have a normal pupil size. The pupil must be narrow enough. Therefore, lighting must be both local and external, so that the pupil size is adequate. You can use lenses that improve contrast sensitivity - the acuity of vision in the twilight.