Night blindness (hemeralopia) - why it occurs, methods of diagnosis and treatment

Hemeralopia (night blindness) is a pathology accompanied by impaired visual adaptation in low light conditions (twilight, darkness, artificial darkness). With hemeralopia, vision of objects in the dark deteriorates, spatial orientation is disrupted, as well as the process of light adaptation, visual fields are narrowed, and problems with color perception are identified.

The popular name for the disease is “night blindness” due to the similarity of its symptoms with the visual characteristics of chickens, which are also poorly oriented in the dark or twilight. The retina of our eye is made up of rod-shaped ("rod") and cone-shaped ("cone") light-sensitive cells that make up the photoreceptor apparatus of the eye. At the same time, “rods” provide black-and-white twilight and night vision, “cones” provide daytime perception of the color palette. On average, the retina contains approximately 110–125 million rods and up to 7 million cones, the normal ratio of which is 18:1.

The rod-shaped cells of the retina have the visual pigment rhodopsin, which provides dark adaptation to vision. This pigment tends to disintegrate in the light, and in the dark, reacting with vitamin A, it is restored. The synthesis of rhodopsin pigment occurs with the release of energy, the conversion of which into electrical impulses gives signals to the optic nerve, which sends impulses to the brain. This mechanism is ensured by the normal functioning of rod-shaped cells. Violation of the ratio of “cones” and “rods” with a lack of rhodopsin leads to the development of hemeralopia, when in low light visual acuity decreases, remaining normal in bright light.

Causes of hemeralopia

In ophthalmology, it is customary to distinguish three types of hemeralopia: congenital, symptomatic and essential.

In congenital hemeralopia, the causes of the disease are genetic factors that are hereditary and familial in nature. A similar pathology is characteristic of Usher syndrome, hereditary retinitis pigmentosa and other inherited pathologies.

What vitamin deficiency causes night blindness?

If you ask what vitamin deficiency causes night blindness, doctors will answer that the most important vitamin for vision is vitamin A, or retinol. In addition to it, vitamins A2 and PP are involved in the synthesis of the rhodopsin pigment in the rod cells of the retina. Other manifestations of retinol deficiency include thinning hair, brittle nails, pustular skin lesions, and respiratory infections. In developed countries, the diet of residents is quite varied, so the disease most often develops due to disturbances in the transportation, transformation and absorption of retinol.

The liver accumulates retinol. It can take up to three years from the onset of vitamin A deficiency to symptoms of night blindness.

Essential hemeralopia can be caused by:

diseases of the gastrointestinal tract (pancreatitis, intestinal lymphangiectasia, intestinal enzymopathies, colitis);
diabetes;
hepatobiliary pathology;
anemia;
treatment with retinol antagonists (quinine);
alcoholism.

Also, increased consumption of retinol can lead to hypovitaminosis and even vitamin A deficiency, for example, with regular hypothermia, high physical activity, and severe stress.

Signs of hemeralopia

Symptoms of congenital hemeralopia develop in early childhood, characterized by persistent vision loss that cannot be cured. Night blindness is accompanied by a decrease in the acuity of twilight and night vision, and a feeling of visual discomfort even in twilight. Patients with hemeralopia note that they cannot distinguish between surrounding objects and lose spatial orientation in low light or when moving from a dark room to a well-lit one. At the same time, in the daytime, as well as with sufficient lighting, visual acuity is usually not impaired.

In addition, with hemeralopia, there may be a feeling of “sandiness” or dryness in the eyes. Children with hemeralopia are afraid of the dark, so they behave restlessly and often cry at dusk. This disease is characterized by a narrowing of visual fields with a decrease in the perception of yellow and blue colors.

Essential hemeralopia is accompanied by the appearance of xerotic Iskersky-Bitot plaques on the conjunctiva, which are flat dry spots that are located within the eye fissure. In addition to eye symptoms, there may be dryness of the mucous membranes and skin, and areas of hyperkeratosis may appear on the body, with peeling and scratching of the skin, and bleeding gums. With acute vitamin A deficiency, softening and ulceration of the cornea (keratomalacia) is often observed.

Diagnostics

The diagnosis of night blindness can only be made by an ophthalmologist based on the patient’s complaints, the main symptoms of the disease and the electroretinography method. The latter allows you to see all the anomalies in the retina.

The basis of the method is that human eyes react to light with specific electrical impulses (biopotentials). An oscilloscope is used to record the obtained data.

As a result, the ophthalmologist receives an electroretinogram, which allows you to see a full picture of the biopotentials of the retina.

Diagnosis of hemeralopia

Deterioration of twilight vision is a reason for an urgent consultation with an ophthalmologist, who will help identify the causes of hemeralopia. Typically, the examination begins with visometry - checking visual acuity, which in the case of essential hemeralopia is often unchanged. Performing achromatic as well as color perimetry makes it possible to detect a concentric narrowing of the visual fields and the presence of the Purkinje phenomenon.

The ophthalmoscopy picture for various types of hemeralopia has some of its own characteristics. Thus, the essential form of hemeralopia is characterized by the absence of changes in the fundus, while in others there are specific changes inherent to the disease that caused night blindness. With genetically determined hemeralopia, ophthalmoscopy reveals small round foci of degeneration on the retina.

The study of dark adaptation requires adaptometry. The functional state of the retina is assessed using electroretinography and other additional electrophysiological studies. Determining the causes of symptomatic hemeralopia may require tonography, refractometry, as well as biomicroscopy using a Goldmann lens, optical coherence tomography, etc. A comprehensive examination of patients with hemeralopia often includes consultations with a gastroenterologist and endocrinologist.

Causes of dangerous pathology

If you discover signs of night blindness, in order to save your vision, you will have to adhere to the basics of comprehensive treatment. Otherwise, the therapy will not give the desired long-term effect.

This is explained by the fact that the human retina consists of two types of cells:

sticks;
cones.

The former are responsible for the ability to see in poor lighting conditions, while the responsibilities of the cones include the ability to recognize colors and control overall visual acuity. As soon as even minor deterioration begins in the retinal cells, this immediately affects the rapid deterioration of well-being, because the patient develops night blindness.

Physiologically, the mechanism is explained by the fact that rods are formed from rhodopsin, which is obtained through cooperation with vitamin A. If light hits the retina, then rhodopsin disintegrates. To regenerate the component, a new vitamin dose is required, which the body simply has nowhere to take from. This makes it clear why the deficiency of useful components is so destructive.

If we consider the general primary sources of pathology without taking into account poor heredity and lack of minerals, then there will still be many other variations due to which hemeralopia is observed:

liver failure;
anemia;
exhaustion of the body against the background of weak immunity, which is an ideal environment for the development of many other ailments, including scurvy;
treatment with vitamin A antagonists.

Various atypical retinal pigment pathologies, retinal detachment, dysfunction of the optic nerve, inflammation, glaucoma, myopia and many other eye diseases can also act as a catalyst for deviation.

In recent years, cases have become more frequent when dangerous signs began to manifest themselves even in healthy people who had no history of night blindness, and a visit to an ophthalmologist did not reveal any specialized eye diseases.

Because of this, many patients begin to panic, asking: what is happening to them? In fact, the reason should be sought in prolonged work at the computer. The clinical picture is aggravated due to poor lighting. With repeated irritation, the nerve endings are damaged, which then signal a problem with the classic symptoms of hemeralopia.

In order not to reach such a deplorable state, experts recommend doing gymnastics, using drops, the name of which will be suggested by the doctor, and also periodically taking a break from the monitor during the working day.

Treatment of hemeralopia

With the congenital form of hemeralopia associated with hereditary pathology, treatment is not carried out; it is incurable. To treat acquired hemeralopia, it is necessary to identify and subsequently eliminate the causes that caused the violation of dark adaptation.

Hemeralopia caused by myopia requires the selection of glasses or contact lenses; laser correction of myopia or refractive surgery (lens replacement, scleroplasty, etc.) may be offered. Hemeralopia caused by cataracts or glaucoma also requires surgical treatment of these diseases (anti-glaucomatous operations, cataract surgery). If the cause is retinal detachment, laser coagulation is indicated.

In case of essential hemeralopia, first of all, it is necessary to normalize the diet, enriching it with foods containing carotene and retinol (butter, cheese, cod liver, milk, eggs, carrots, tomatoes, spinach). In addition, instillation of vitamin drops for the eyes and oral forms of vitamin A, riboflavin, and nicotinic acid are prescribed, according to age-specific dosages. At the same time, treatment of gastrointestinal diseases and diabetes mellitus is mandatory (with monitoring of blood glucose levels and insulin therapy).

Treatment of the disease: how to get rid of night blindness

Therapy depends on the cause that led to hemeralopia. If the condition is symptomatic - caused by other diseases - then the underlying disease is treated. For example, in case of night blindness caused by myopia, correction agents are prescribed or laser vision correction surgery is performed. Surgery is also prescribed for glaucoma or cataracts.

Night blindness from a lack of vitamin A first of all requires normalization of nutrition. Doctors recommend including meat, fatty fish (salmon, cod liver), dairy products (cheese, butter, milk), carrots, spinach, and chicken eggs in your diet. Medications are also prescribed: eye drops rich in vitamin A, riboflavin, nicotinic acid. Diseases of the liver, gastrointestinal tract, and thyroid gland are diagnosed, and if problems are identified, appropriate treatment is prescribed.

The prognosis for night blindness is usually positive. With timely detection of hemeralopia and correct treatment of the underlying disease, it is possible to completely restore high-quality vision to the patient.

Prevention of hemeralopia

Symptomatic hemeralopia, depending on the severity of the underlying disease during treatment, can lead to both the restoration of dark adaptation of vision and its permanent loss. Functional hemeralopia usually responds well to therapy with complete restoration of twilight vision.

However, patients suffering from hemeralopia often develop a pathological fear of the dark, which takes on the nature of a phobia or obsessive-compulsive disorder, which is a mental disorder.

To prevent hemeralopia, it is necessary to ensure that the body receives the necessary vitamins, as well as adequate protection of the retina. To achieve this, treatment of concomitant pathologies, adequate nutrition, and the use of sunglasses must be provided, both outdoors and when working with harmful radiation. People with hemeralopia are not recommended to use fluorescent lamps. Children with mild myopia need to wear glasses in the evening.

In the medical department, everyone can undergo examination using the most modern diagnostic equipment, and based on the results, receive advice from a highly qualified specialist. The clinic is open seven days a week and operates daily from 9 a.m. to 9 p.m. Our specialists will help identify the cause of vision loss and provide competent treatment for identified pathologies.

You can make an appointment at the Moscow Eye Clinic by calling 8 8 (499) 322-36-36 (daily from 9:00 to 21:00) or using the online registration form.

Folk remedies

Photo: organicauthority.com

Folk recipes for combating night blindness also suggest diversifying your diet with fresh fruits, berries, vegetables, especially green ones - green onions, celery, spinach, parsley. A salad of grated carrots with vegetable oil, millet porridge, quickly cooked liver, cream, egg yolk, fresh blueberries and currants will be very useful.

A remedy that has long been popular is fish oil. Fish oil has been used to prevent rickets because it is high in vitamin D, but it also contains large amounts of fat-soluble vitamin A. To combat night blindness, it is enough to take one tablespoon for 3-4 weeks.

Decoctions and infusions that are used for night blindness.

Infusion of red rose. Place a teaspoon of dried rose petals in a glass of water, pour boiling water over it, leave until it cools. Take three glasses a day.
For a decoction, take dandelion leaves and roots, blueberry grass, linden flowers, a tablespoon each, buckwheat and sea buckthorn leaves, half a tablespoon each, boil in 1 liter of water for 15 minutes, let it brew for 30-40 minutes and take one glass a day, pre-strained.
Young shoots of stinging nettle, two tablespoons, are infused in boiling water for one hour and drunk a third of a glass during the day before meals.
An infusion of eyebright herb is prepared in the evening by pouring cold boiled water and leaving to infuse overnight (8-9 hours). In the morning, strain and take a quarter glass three to four times a day.

Decoction of rose hips. Give three tablespoons for two glasses of water and boil for 10 minutes. Take two glasses a day.

The information is for reference only and is not a guide to action. Do not self-medicate. At the first symptoms of the disease, consult a doctor.

What to do with night blindness

Many people note that their vision noticeably worsens in the evening. Moreover, similar symptoms can be observed even in those who have never had visual impairments. What causes the decrease in visual acuity in the evening, is it possible to cope with this phenomenon? Let’s look at this in this article.

How does night blindness, or blurred vision in the evening, manifest itself?

A condition in which twilight vision deteriorates is called night blindness, or hemeralopia. It is characterized by a decrease in visual acuity and loss of spatial orientation at dusk or in poor lighting. The main symptoms of hemeralopia are decreased sensitivity to light, impaired vision adaptation to darkness, and narrowing of the visual fields. At the same time, in the daytime and in good lighting, a person can see normally.

Ophthalmologists note that it is not an independent disease. More often it indicates the presence of an ophthalmological disease, a lack of vitamins or eye fatigue. In any case, hemeralopia seriously affects the quality of life of people, especially in winter, when daylight hours are greatly reduced.

Why vision deteriorates in the evening: the main causes of hemeralopia

Experts identify several reasons that cause twilight and night vision disorders.

Heredity.

In some cases, hemeralopia is present in a person from birth and persists throughout life.

Vitamin A deficiency.

Retinol is one of the most important vitamins for vision. It is part of rhodopsin (visual pigment) and plays a critical role in the process of light perception. The daily intake of vitamin A for adults ranges from 800 to 1000 mcg. If, for one reason or another, not enough retinol enters the body, a person’s night vision deteriorates and “night blindness” develops.

Eye diseases.

Hemeralopia may be a symptom of some ophthalmological diseases. Poor vision in the dark and at twilight may indicate degenerative changes in the retina, inflammatory diseases of the choroid and retina, optic nerve atrophy, glaucoma and other eye diseases. As a rule, in such cases, “night blindness” is not the only symptom and is accompanied by other clinical manifestations of the disease.

Eye fatigue.

Another common reason why vision decreases in the evening is eye fatigue. If you spend all day in the office at the computer, watch a lot of TV, do sewing or other work that requires good near vision, then in the evening excessive muscle tone occurs. This leads to the fact that distant vision in the evening deteriorates noticeably. The danger of frequent eye fatigue is that regular overstrain of the accommodative muscles can sooner or later lead to myopia, and then appropriate correction will be required.

Main types of night blindness

Depending on the cause that caused hemeralopia, there are several types of night blindness.

Congenital.

In this case, the disorder of twilight and night vision is hereditary and permanent. Congenital hemeralopia manifests itself already in childhood or adolescence and is characterized by a persistent decrease in vision in the dark and a disrupted process of adaptation to changes in illumination. This type of night blindness cannot be cured.

Essential.

This type of hemeralopia occurs when vitamin A is insufficiently supplied to the body or its absorption is impaired. Most often, essential hemeralopia develops in people who adhere to unbalanced diets, eat poorly, suffer from alcoholism, liver disease, and neurasthenia. Impaired absorption of retinol is typical for patients with endocrine diseases, reduced immunity, hepatitis, chronic diseases of the pancreas and gastrointestinal tract. This type of “night blindness” responds well to treatment: it is enough to normalize the intake of retinol in the body or restore metabolic processes.

Symptomatic.

This is a twilight vision disorder that is a symptom of other eye diseases. Therapy in this case consists of treating the underlying disease.

"False night blindness."

If evening vision deteriorates at times due to daytime eye fatigue, then this type of hemeralopia is called “false night blindness.”

Risk groups: who experiences vision loss in the evening?

Night blindness can develop in people of any gender. However, during menopause, serious hormonal changes occur in the female body, due to which the risk of developing hemeralopia becomes several times higher than among representatives of the stronger sex of the same age.

Several other categories of people are also at risk:

• socially vulnerable segments of the population whose diet is depleted in vitamins, including retinol; • adherents of unbalanced strict diets; • patients with chronic diseases that affect the absorption of vitamins; • people over 40 years old, because retinal nutrition deteriorates with age; • patients with certain ophthalmological diseases; • people who work a lot on the computer.

Why is poor vision in the dark dangerous?

Hemeralopia not only reduces the quality of life of patients, it can be truly dangerous.

Firstly, if you don’t pay attention in time to the fact that your vision is diminishing and adaptation to darkness is impaired, you can miss a dangerous ophthalmological disease that will lead to irreversible changes.

Secondly, according to European doctors, night blindness causes road accidents no less often than drunk driving. People who have impaired light perception may not notice dangers on the road, which leads to accidents. For this reason, commissions that determine the professional suitability of drivers and other specialists often conduct a night blindness test.

Deterioration of vision in the evening: diagnosis, treatment and prevention

In most cases, night blindness is treatable, so if your vision in the dark has worsened, you should see an ophthalmologist as soon as possible.

Diagnosis usually includes analysis of patient complaints, study of clinical symptoms and electroretinography, which allows us to determine the presence of retinal abnormalities.

Also, for diagnostic purposes, the doctor may conduct the following studies:

• perimetry - determination of visual fields; • electrooculography - assessment of the state of the eye muscles and the surface of the retina during movements of the eyeball; • adaptometry - testing for light perception.

Based on the diagnostic results, the specialist determines the type of hemeralopia and prescribes appropriate treatment.

If “night blindness” is associated solely with overwork, then the doctor will recommend changing your work schedule: resting your eyes, taking frequent breaks, maintaining a distance between your eyes and the computer monitor, and performing special exercises. Correct lighting, which should be moderately bright and comfortable, helps to avoid visual fatigue. It is not recommended to work at a monitor or watch TV in the dark.

With essential hemeralopia, it is important to increase the intake of vitamin A into the body or eliminate the causes that interfere with its absorption. With this form of the disorder, diet therapy is often prescribed, which involves a balanced diet and consumption of foods with large amounts of retinol and other vitamins. With “night blindness” you need to eat a lot of fresh berries and fruits (blueberries, black currants, gooseberries, apricots, peaches), herbs and vegetables (carrots, spinach, tomatoes, green peas), as well as cod liver, butter, cheese, eggs , milk. If necessary, the doctor will prescribe a complex of vitamin preparations that compensate for the lack of retinol in the body.

The success of treating symptomatic hemeralopia directly depends on the severity of the underlying disease. If it can be treated or corrected, then the night vision disorder will also be reversible. For example, surgical treatment of myopia or glaucoma in most cases helps to restore clear vision to the patient and restore the light sensitivity of the retina, thereby relieving him of night blindness.

The only form of hemeralopia that cannot be treated is congenital. However, to reduce the severity of symptoms, a specialist may prescribe vitamins and diet therapy.

For people who are at risk for developing hemeralopia, but do not yet have symptoms of this disorder, doctors recommend taking preventive measures:

• eat a balanced diet, eating plenty of foods with vitamin A; • protect your eyes from bright light (dazzled headlights, flashlights, reflected light rays); • regularly visit an ophthalmologist for timely diagnosis of myopia or ophthalmological diseases; • undergo an annual medical examination to identify chronic diseases and conditions that can trigger the development of hemeralopia.

Paying close attention to eye health will help prevent the development of night blindness and maintain good vision in the dark.

Come for a diagnosis at the Kazakh Research Institute of Eye Diseases at the address: Almaty, Tole bi street, 95a (corner of Baitursynov street). Telephone; +7 (727) 279 54 36

Prevention

The hereditary form of the disease cannot be prevented. If the disease is caused by a nutritional factor, that is, a reduced supply of nutrients to the blood, it is recommended to adhere to the following rules:

a balanced diet, with the help of which the body receives all useful substances and vitamins;
consumption of vitamin complexes in the autumn-winter period, when their amount in products is reduced;
timely treatment of all inflammatory diseases of the gastrointestinal tract to prevent malabsorption of nutrients.

Night blindness is a disease due to which a person loses perception of the surrounding space during twilight. To prevent the development of complications, you should fully adhere to the doctor’s recommendations for treating the disease.

Other reasons for the development of pathology

The inability to see at dusk develops not only due to vitamin deficiency. Various diseases can also cause this pathology. The cause of visual impairment may be:

Ophthalmic diseases that are associated with retinal detachment.
Severe diseases of the liver and biliary tract.
Low hemoglobin.
Lack of a certain pigment in the tissues of the eye.
Some genetic diseases.
Oncological diseases of the brain.

The cause of deterioration in visual function may also be a plant called night blindness. This plant has small blue flowers and a slightly velvety stem. If the juice of such a flower gets on the mucous membrane of the eye, it becomes irritated and the person begins to see poorly in the dark.

In addition, metabolic disorders can also lead to a similar problem. This may be a consequence of poor nutrition or systemic diseases of internal organs.

Only a qualified doctor can accurately determine the root cause of night blindness.