Blindness - causes and diseases causing vision loss

Blindness implies a severe visual impairment in which a person is unable to see due to pathological changes in the visual apparatus. With this pathological condition, the perception of visual stimuli may be partially reduced or lost completely. Taking into account the nature of origin, congenital and acquired blindness are distinguished. Treatment of the pathology depends on the cause of its occurrence and is selected individually.

Causes of blindness

Blindness is a whole group of diseases characterized by partial or complete loss of vision or color perception. This pathological condition is a common problem in the modern world, which leads to disability. Congenital vision loss can occur for the following reasons:

• retinopathy of prematurity;
• congenital rubella syndrome;
• albinism;
• hereditary predisposition;
• genetic mutations;
• Bardet-Biedl syndrome;
• taperetinal degenerations;
• aplasia of the eyeball.

Congenital blindness also occurs as a result of infection of the fetus with pathogens such as rubella, tuberculosis or influenza. Children suffering from severe retinol deficiency are at risk. There are 2 types of hereditary blindness: complete and partial.

Acquired blindness most often occurs due to cataracts or traumatic damage to the visual organs (sometimes to the brain). What diseases lead to complete blindness? In adulthood, vision loss can develop against the background of the following pathological conditions:

• age-related cataract;
• glaucoma;
• retinopathy in diabetes mellitus;
• degeneration of the optic spot;
• optic nerve atrophy;
• trachoma;
• xerophthalmia;
• onchocerciasis;
• keratomalacia;
• pigmentary rhinitis;
• violation of corneal permeability.

In many cases, pathology in people under 30 years of age is caused by eye injury, which often occurs in industrial conditions. Damage can be not only mechanical, but also chemical. The perception of visual stimuli can also be impaired due to methanol poisoning.

Every year the number of blind people increases. And it has been observed that blindness in one or both eyes most often affects people in developing countries around the world.

Sometimes the pathology occurs from smoking, due to damage to the vascular systems, which causes vision loss.

Symptoms

The main manifestation of the disease is the absence of visual sensations. Deterioration of vision can be sudden and complete, or it can be gradual, characterized by the presence of light perception. Sometimes a person with this problem has residual vision (0.01-0.05 diopters) in one eye, which can see with proper glasses correction. If a symptom of a child's blindness is the lack of reaction of the pupil to light, then a complete loss of vision is detected. Sometimes a perceptual (false) form of the disease is diagnosed.

This disease can manifest itself with the following symptoms:

• impaired color perception;
• loss of visual fields;
• decreased visual acuity;
• scotomas;
• problems with orientation in space;
• delay in the formation of movements.

Blind people experience significant difficulties with assessing spatial orientation, distinguishing between objects and colors. The quality of life is significantly reduced, difficulties arise with performing usual actions and movements. In case of blindness, the core of the sensory organization of the tactile-kinesthetic-auditory type is formed, the loss of vision is compensated by the strengthening of other senses (hearing, smell, tactile sensations). Congenital blindness in children leads to various complications.

In addition to the above symptoms, children often experience a main speech defect in blindness in the form of tongue-tied speech.

What are the types of violation?

Vision loss is not considered a separate disease and occurs as a result of exposure to certain factors. The following types of blindness are distinguished:

One of the variants of the pathology is the loss of the ability to see well at night.

• Absolute. A person does not see anything, does not distinguish between light and darkness, shape and distance between objects.
• Practical blindness. The patient retains residual vision. The eyes do not provide complete information about the surrounding space, but you can distinguish colors and perceive light.
• Colorblindness. The patient does not distinguish or sees colors incorrectly. The full form of the pathology is rarely diagnosed. The disorder is 8 times more common in men than in women.
• Night blindness. The term means that any person sees worse in the dark than in light, but against the background of this pathology, night vision deteriorates significantly.
• Snow blindness. A temporary disease that develops due to a person receiving a large dose of ultraviolet radiation, which leads to swelling of the cornea.

Classification

Taking into account the degree of damage to the visual organs, ophthalmology distinguishes several forms of this disease:

1. Full. Both eyes do not perceive visual stimuli, and the pupils do not react to light. In medical terms, complete loss of vision is called amaurosis.
2. Partial (practical) . Residual vision is observed, color perception and light perception are preserved.
3. Subject. The pupils react to changes in the intensity of light pulses, but a person is not able to distinguish the shape of surrounding objects.
4. Hysterical. Develops against the background of mental trauma, due to excessive excitability. No eye changes are observed.
5. Civil. The patient cannot see his fingers at a distance of 3 meters, as a result of which he is unable to move normally and ensure a normal existence for himself. People with this form of pathology need outside help.
6. Professional. Visual impairment interferes with the performance of professional duties.
7. Cortical. The occipital lobes of the cerebral cortex are affected, the reaction to light is preserved.

The following specific types of pathological conditions are also distinguished, accompanied by partial loss of vision:

1. Chicken blindness. Visibility in the dark deteriorates significantly; a person cannot see objects and cannot move independently. This form can be congenital or acquired (as a result of certain diseases). In good lighting, people with this diagnosis see very well.
2. Snow blindness . This is the name for temporary blindness from bright light, which occurs as a result of powerful ultraviolet irradiation of the eyes. Temporary blindness from bright light is a consequence of swelling and growth of the cornea. With this disease, complete loss of vision never occurs; short-term blindness in one eye is often observed.
3. Colorblindness. The perception of the color spectrum is impaired; a person is unable to correctly identify colors. Most often, the patient cannot distinguish only some colors; complete color blindness is quite rare. This disease is usually genetic in nature and occurs predominantly in men.

Read in a separate article: Retinal hemorrhage: causes, types and treatment

Visual impairment can be permanent or temporary. Sometimes false vision loss occurs. There is such a rare form of vision loss as onchocerciasis (river scotoma), which develops as a result of damage to the visual organs by midges that live in fast-flowing rivers.

In the presence of cognitive impairment, a cognitive form of the disease may develop.

How to develop peripheral vision?

Developmental exercises help achieve the following goals:

• improvement of brain activity;
• a person begins to better navigate in space;
• Speed ​​reading develops.

Let's consider effective exercises that will help develop lateral vision:

1. Fix your gaze on the object and try to simultaneously recognize objects located on both sides.
2. Concentrate your gaze on an object located three meters away from you. Take a pencil in your hands and spread your hands. In this case, you should see not only the main object, but also the pencils.
3. Take the pencils again and spread your hands. Raise your right hand up and watch the pencil in this hand with your right eye. At the same time, lower the left pencil and watch it with your left eye. Next, the pencils are brought to the center. Then move the objects diagonally and return to the starting position.
4. On sheets of paper, draw large letters or numbers in bright colors. Observe the drawings while constantly increasing your viewing angle. As peripheral vision develops, smaller pictures can be used.
5. Concentrate on the subject, while paying attention to the subject located in the periphery. There should be more and more of these items.

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So, peripheral vision is no less important than central vision. The ability to see peripheral objects allows you to navigate well in space. Impaired lateral vision may indicate the presence of serious pathologies, including: glaucoma, scotoma, retinal detachment, disruption of brain function, neoplasms, and others. In order not to miss dangerous diseases, it is important to contact an ophthalmologist in a timely manner and follow his recommendations.

Diagnostics

If visual acuity has decreased significantly, scotomas have appeared, or visual fields have begun to fall out, you should immediately consult a doctor, since such manifestations indicate serious vision problems. It is also necessary to contact an ophthalmologist if damage to the visual organ occurs. To diagnose blindness, the following diagnostic measures are carried out:

• ophthalmoscopy;
• visometry;
• perimetry;
• fluorescein angiography;
• electroretinography;
• campimetry.

Using these studies, the specialist determines the degree of visual impairment. Complete blindness is minus 30 or more. Various blindness tests are performed to detect color vision impairment. To detect the problem in a timely manner and prevent the development of severe complications, it is necessary to contact an ophthalmologist as early as possible. If a sudden bursting pain occurs in the eye, scotomas form, an eye burn or penetrating injury occurs, you should immediately call an ambulance.

Timely contact with doctors will help preserve your vision.

What can cause loss of peripheral vision?

There are various reasons that can cause loss of peripheral vision. Regardless of the final diagnosis, if your vision changes quickly, it should be considered a medical emergency. If you cannot get to an ophthalmologist immediately, go to the nearest emergency room. One thing that is important in recognizing peripheral vision loss is that the problem may not be related to problems with your vision at all. One of the symptoms of a stroke is sudden loss of peripheral vision. If you are suffering from a stroke, prompt medical attention can make a significant difference to your long-term health. Often, loss of peripheral vision can be a problem only in your eyes. A retinal detachment makes it feel like you have a curtain hanging on one side of your face, eliminating all vision on one side. Other problems occurring in the retina of the eye can also lead to tunnel vision or loss of peripheral vision. Retinal degeneration, pigmentary disease and retinopathy are all conditions that can lead to problems with peripheral vision.

One common reason why many older adults may lose their peripheral vision is due to glaucoma. Glaucoma victims gradually lose their vision until they are left with complete tunnel vision. Some patients who develop glaucoma also experience eye pain and redness, as well as nausea and vomiting.

Many people fear the worst when they lose part of their vision. It is important to understand that very few people suffer from the worst cause of peripheral vision loss, which is a brain tumor. Other symptoms that, when combined with impaired peripheral vision, may indicate a brain tumor include sudden onset of headaches, nausea and vomiting, problems with balance and difficulty speaking. Other people may notice changes in their personality. Seizures are also a common symptom of brain tumors.

Peripheral vision loss is not necessarily permanent. Some people lose their peripheral vision with the onset of a migraine. Other migraine symptoms include headaches severe enough to prevent you from participating in normal activities, throbbing pain in the head, or sensitivity to light or sound.

There are many reasons why you may lose your peripheral vision. Some of these conditions are permanent, while others are temporary. Some of them require emergency medical attention, while others that are less serious do not. It is important for you to treat any sudden changes in your vision as a medical emergency and go to an ophthalmologist or emergency room immediately.

Treatment and prognosis

The likelihood of regaining lost vision depends on the cause of blindness. If the pathological condition arose as a result of cataracts, glaucoma, an inflammatory process or an infectious lesion, then to return the perception of visual stimuli it is sufficient to eliminate the primary disease. Retinal detachment requires surgery. There is no specific cure for blindness.

Many types of total blindness are reversible. However, visual disturbances caused by optic nerve atrophy or cerebral hemorrhage cannot be treated. Congenital color blindness also cannot be treated. If the pathology cannot be cured conservatively or surgically, then an individual plan is selected aimed at improving the patient’s quality of life. Compensation for blindness and low vision is carried out using the following scientific methods:

1. Guide dogs . Specially trained animals help sick people move around the streets.
2. Computer electronic devices : audio books, various manuals in Braille, voice reading programs, models of visual replacement devices, Braille keyboards, and so on.
3. Specialized computer programs for the blind . Modern computer companies have taken care of people with disabilities and created tactile electromechanical panels, Braille and speech input-output, operating systems for the blind Oralux and Adriane Knoppix. A special web technology WAI-ARIA was also created.
4. Bionic eye. The essence of this technology is to implant a retinal prosthesis and integrate a camera into special glasses, which interacts with a video processor and photosensor, sending electrical video signals to the brain.

A guide dog is an excellent assistant for a visually impaired person.

In developed countries, biocells are used in the treatment of blindness. Stem cell treatment is also practiced. The prognosis for the development of amaurosis is in most cases unfavorable. The patient is registered with an ophthalmologist throughout his life. And since such a sudden deterioration in vision (even partial) negatively affects the quality of vision, patients often additionally have to consult a psychiatrist.

Causes and factors of occurrence

Most often, loss of half the visual field is caused by pathological changes in the brain affecting the area of ​​the optic chiasm or behind it, as well as the cerebral cortex in the area of ​​the inner surfaces of its occipital lobes.
Depending on the level of damage, various types of hemianopsia occur. The nature of visual field loss depends on the cause that causes it. The most common cause is diseases of the light-receiving apparatus of the eye.

If the loss of the visual field looks like a curtain on any side, the cause is either retinal detachment or a disease of the visual system pathways. With retinal detachment, in addition to loss of the visual field, distortion of the shape and broken lines may be observed. In addition, the amount of visual field loss may be different in the morning and evening.

Sometimes patients note that they see the image as if through water (it “floats”).

The causes of retinal detachment can be high myopia, retinal dystrophy, or previous eye trauma.

If the outer halves of the visual field (from the temple) fall out, especially in two eyes, an enlargement of the pituitary gland (adenoma) can be suspected.

Loss of the visual field in the form of a dense or translucent curtain from the nose may be one of the signs of glaucoma, and “fog” or colored rainbow circles may be periodically observed when looking at a light bulb.

Loss of the visual field in the form of a translucent curtain on any side can be caused by opacities of the optical media of the eye, such as: cataract, pterygium, cataract, opacification of the vitreous body.

If some area in the center of the visual field falls out, the cause is a malnutrition of the central zone of the retina (macular degeneration) or the optic nerve (partial atrophy).

Macular degeneration, in addition, is often accompanied by distortion of the shape of objects, curvature of lines, and changes in the size of individual parts of the image.

Concentric narrowing of the visual field (tube vision) is most often a consequence of a special form of retinal dystrophy - its pigmentary degeneration, while high central visual acuity remains for quite a long time.

Advanced glaucoma can also cause a concentric narrowing of the visual field, but with it the acuity of central vision suffers much earlier.

In everyday life, a concentric narrowing of the visual field manifests itself as follows: a person approaches the door, takes out the key and looks for the keyhole for a long time. Such people become almost helpless in an unfamiliar environment; they need a lot of time to familiarize themselves with it.

With sclerosis of the cerebral vessels with impaired nutrition of the visual center of the cerebral cortex, a concentric narrowing of the visual field can also be observed, but it is more often accompanied by a significant decrease in the acuity of central vision, forgetfulness, and dizziness.

Source https://www.glazmed.ru/lib/public09/what008.shtml

There are many factors that provoke the development of short-term blindness. But experts identify a number of reasons that are the most common. The disease can develop when:

• Thrombosis of spinal vessels
• Intracranial pressure (hypertension)
• Acute glaucoma
• Diabetes mellitus
• Optic neuritis
• Retinal detachment
• Functional disorders
• Neovascular macular degeneration

In addition to the above reasons, there are others that relate to diseases of the cardiovascular system.

During a hypertensive crisis, short-term vision loss may also develop. First, a person experiences goosebumps, dark spots or flashes before his eyes, and only then he completely loses the ability to see with one or two organs of vision at once.

A stroke may cause loss of vision that lasts up to three hours. After this time, vision returns again.

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Prevention measures

There are no specific preventive measures to prevent the development of blindness. However, it is possible to prevent the development of this pathological condition if you avoid various damage to the visual apparatus and brain, treat existing diseases in a timely manner and regularly visit an ophthalmologist for the purpose of prevention. When the first signs of visual impairment appear, you should immediately consult a doctor.

Every year there are new advances in ophthalmology in the fight against blindness, so in many cases it is possible to restore vision.

Author of the article: Kvasha Anastasia Pavlovna, specialist for the website glazalik.ru