Night blindness: causes, symptoms and treatment
Night blindness is a disease of the organs of vision, which is characterized by a deterioration in its quality in conditions of insufficient illumination, for example, at dusk, in the dark, with artificial dimming, etc.
In ophthalmic practice, there is no such term as "night blindness". It is used mainly in everyday speech. Doctors call night blindness hemeralopia.
Night blindness worsens a person's quality of life, since at night his field of vision narrows, his ability to perceive colors is impaired, and his spatial orientation deteriorates. If you find such symptoms in yourself, you need to consult a doctor, since acquired night blindness is treatable.
The name of the pathology was given due to the fact that its symptoms have a certain similarity with the visual capabilities of chickens. In the evening, these birds find it difficult to navigate in space.
The human eye, namely its retina, consists of rods and cones. This is the name of the cells that react to light. The rods are responsible for nighttime black and white vision, and the cones are responsible for daytime vision. The retina contains more rods than cones. Their normal ratio is 18: 1. If the balance is disturbed, then the person develops night blindness. At the same time, during the day, he sees everything as before.
The sticks contain a pigment called rhodopsin. He is responsible for the adaptation of the organ of vision in the dark. When exposed to light, the pigment disintegrates, and in the dark it is restored again. This process takes place with the participation of vitamin A.
When rhodopsin is produced in the rods, energy is released. It is transformed into electrical signals that travel to the brain through nerve fibers. This ensures night vision.
Video: what is night blindness?
- Causes of night blindness
- Symptoms of night blindness
- Diagnosis of night blindness
- Night blindness treatment
- Prevention of night blindness
Causes of night blindness
There are three types of night blindness: congenital, symptomatic, and essential.
Congenital night blindness is a hereditary pathology. It is diagnosed with retinitis pigmentosa, with Asher's syndrome, etc.
Various diseases can lead to the development of symptomatic night blindness, including:
- Myopia with a drop in vision down to -6.
- Retinal detachment.
- Optic nerve atrophy.
- Siderosis, in which iron salts are deposited in the tissues of the eyeball.
- Eye burns of radiation etiology.
Essential night blindness develops in people who are deficient in vitamin A, PP and B2. often patients with the following diagnoses face such a violation:
- Liver cirrhosis and other organ pathologies.
- Diseases of the digestive system, for example, gastritis, colitis, enteritis, etc.
- Exhaustion of the body.
- Prolonged exposure of bright light to the retina.
Essential night blindness can develop in patients who take quinine, as this substance is a retinol antagonist.
Separately, it is necessary to highlight the factors that can become a trigger for the development of night blindness:
- Viral diseases that a person has suffered: herpes, rubella, chickenpox, measles, etc.
- The entry of a woman into the menopausal period.
- Compliance with a diet that involves avoiding animal products.
After a person has developed a deficiency of one or another vitamin, he will not have an instant onset of night blindness. As a rule, its first symptoms appear only 2 years later from the manifestation of vitamin deficiency.
Regardless of what exactly caused the development of night blindness, the pathology mechanism is the same: the production of rhodopsin is disrupted in the rods of the retina.
Symptoms of night blindness
If the disease is inherited to a child, then already in early childhood, he will experience a decrease in vision. It will not be possible to get rid of the problem. The congenital form of the pathology does not respond to treatment.
Visual acuity in congenital night blindness at night is significantly reduced. In the twilight, a person feels uncomfortable, he finds it difficult to orient himself in space, does not see the objects around him. At the same time, in the daytime, a child with congenital night blindness does not complain of any vision problems. He sees objects well at far and near distances. At dusk, red colors seem even darker to the patient, and blue ones are lighter. In general, vision in the dark seems to be blurred. This effect was discovered in 1819 and is called the Purkinje phenomenon.
For a person to be able to read or write in the evening, he needs a bright light.
Other symptoms of congenital night blindness include complaints of a feeling of grit in the eyes. Children with this disorder often suffer from a fear of the dark, and show pronounced anxiety as dusk falls. The fields of vision are narrowed, the patient perceives the blue and yellow colors worse.
If a person develops an essential form of night blindness, then on the conjunctiva he will have noticeable flat dry areas in the form of a spot. These spots are called Iskersky-Bito plaques.
Other symptoms of essential night blindness include:
- Dry skin.
- Dry mucous membranes.
- Peeling skin.
- Itchy skin.
- Bleeding gums.
- Corneal ulceration and softening.
These symptoms are associated with a vitamin A deficiency.
Diagnosis of night blindness
If a person notes that his vision began to deteriorate and in the evening he began to see worse, he needs to consult an ophthalmologist.
The first examination that the doctor will prescribe is visometry. It will assess the degree of visual acuity. With night blindness, most often this parameter remains within the physiological norm.
Revealing the narrowing of the visual fields and the violation of the Purkinje phenomenon allows such a study as achromatic and color perimetry.
If the patient develops essential night blindness, the doctor will not find any pathological changes in the fundus. If the disease is a consequence of other disorders, then changes in the fundus will have the specifics of the underlying pathology.
If a patient is diagnosed with congenital night blindness, then the retina will be covered with small foci of degeneration. These foci have a rounded shape.
To assess the possibilities of dark adaptation of the organs of vision, it is necessary to send the patient for adaptometry.
Other studies that can help clarify the diagnosis include:
- Optical coherence tomography.
- Refractometry, etc.
If necessary, the patient can be referred for a consultation with a gastroenterologist or endocrinologist.
Night blindness treatment
The hereditary form of the disease is incurable. A person's visual acuity at dusk will be reduced, regardless of the measures taken.
When the disease has been acquired during life, it is necessary to establish the factor that provoked night blindness. Only after that it will be possible to choose the optimal treatment regimen.
If night blindness is a consequence of myopia, then the patient will need to wear glasses. They are selected depending on the characteristics of a particular person's vision. Glasses can be replaced with contact lenses. According to indications, laser vision correction, scleroplasty, lens replacement surgery, etc. can be performed.
With night blindness, provoked by cataracts or glaucoma, the patient is shown surgical intervention. This can be cataract phacoemulsification, antiglaucomatous surgery, cataract extraction.
Laser coagulation is prescribed for patients with retinal detachment.
The essential form of the disease responds well to treatment. The patient is required to draw up an individual nutritional plan. The menu should include foods rich in carotene and retinol.
These products include:
- Cod liver.
- Cheese and milk.
- Chicken eggs.
- Tomatoes and spinach.
Video: The importance of Vitamin A in night blindness:
The patient is given installations with eye drops enriched with a vitamin component. It is imperative to additionally take vitamin A, riboflavin, niacin.
Patients with diabetes need to receive sugar-burning medications or insulin injections to control blood glucose levels. Patients with disorders in the work of the digestive tract are prescribed appropriate treatment.
As for the prognosis for recovery, it completely depends on which pathology led to the deterioration of twilight vision. Perhaps both complete recovery and complete blindness. In most cases, it is still possible to get rid of night blindness.
The complications of the disease include the formation of phobias and fear of the dark. In the future, this can provoke a mental disorder.
Video: Simple Ways to Improve Night Vision:
Prevention of night blindness
Preventive measures can be as follows:
- A person must eat right so that his body does not need any vitamins and microelements.
- When exposed to the sun, you need to wear sunglasses.
- It is imperative to protect the eyes with special means if a person works in conditions of harmful radiation.
- In the presence of diseases of the organs of vision, it is necessary to contact an ophthalmologist in a timely manner.
If a patient is diagnosed with night blindness, then he should not use fluorescent lamps to illuminate the room.
The author of the article: Degtyareva Marina Vitalievna, ophthalmologist, ophthalmologist