Why can't the blind lead the blind?
There are also acquired causes that lead to blindness. Some people only lose their sight in the course of their lives. The most common is blindness due to illness. But accidents and injuries can also make people blind. Some examples!
Poor vision in one eye (weak vision, amblyopia) can develop in childhood. No physical causes can be found for this. Nevertheless, the brain switches off the visual impressions of the eye for no known reason. If the weak-sightedness occurs in both eyes, blindness can be the result.
Age-related macular degeneration (AMD)
Age-related macular degeneration is the most common cause of severe visual impairment from the age of 60. From the age of 80, it is the most common cause of blindness. In AMD, visual cells in the center of the retina (macula = yellow spot), which are responsible for colored and sharp vision, perish as a result of the aging process.
At first, those affected see blurred and blurred, later a dark spot appears in the center of the field of view. Seeing is only possible at the edge. Orientation in space and reading and writing become impossible over time. An estimated 50 percent of cases of blindness can be traced back to age-related macular degeneration. In addition to age, risk factors for AMD include smoking, exposure to light (especially UV radiation) and high blood pressure. Genetic predisposition also plays a role.
Green star (glaucoma) and blindness
In the case of glaucoma, the intraocular pressure is usually increased, which in many cases goes unnoticed for a long time. If the blood flow to the optic nerve is disturbed, it can be damaged. Usually glaucoma first affects one eye, and later also the second. Many only become aware of the glaucoma when they have already lost some of their eyesight. The reason for the increased intraocular pressure are various eye diseases. Glaucoma is responsible for about 20 percent of all cases of blindness. In the case of glaucoma, ophthalmologists first lower the pressure with the help of eye drops. Surgery can also lower the pressure in the eye.
In cataracts, the lens of the eye gradually becomes cloudy because substances are deposited there and cloud the view. Cataracts are easy to operate: the doctor replaces the clouded lens with a new plastic lens. In industrialized countries, cataracts are very rare as an acquired cause of blindness. It is different in developing countries, where medical care is poor. The cataract is still a common cause of blindness there.
Diabetes and blindness
The diabetes mellitus disease slowly damages the blood vessels. They gradually "saccharify" when the blood sugar level is permanently too high. The fine vessels in the retina in the eye (diabetic retinopathy), which can burst, are also affected. The retina also swells and is poorly supplied with oxygen. As a result, those affected see less clearly. If doctors do not treat diabetic retinopathy in a timely and adequate manner, there is a risk of blindness from diabetes. Diabetic retinopathy is considered to be the main cause of blindness in the middle ages of 40 to 80 years.
A cerebral infarction sometimes also damages those regions in the brain that are responsible for vision. The optic nerves are poorly supplied with blood and supplied with oxygen. Sometimes the nerves partially or even completely stop working. Acting quickly is therefore essential in the event of a stroke in order to keep the damage to the brain as low as possible. Incidentally, visual disturbances are also a sign of a stroke!
Vascular occlusion in the eye
In most of the elderly patients, an artery or vein seals the fundus of the eye. This vascular occlusion leads to a lack of oxygen and damages the tissue. The sensory cells (rods and cones of the retina) and nerve fibers of the optic nerve are extremely sensitive to disturbances. If the degradation products are no longer removed, those affected can suddenly go blind on one side. Most of them do not feel pain, but the experience is extremely frightening.
The reasons for a vascular blockage in the eye ("stroke in the eye") can be age-related changes in blood vessels (arteriosclerosis), increased blood pressure, insufficient blood sugar control in diabetics, increased cholesterol levels in the blood or heart diseases (especially cardiac arrhythmias).
Injuries and accidents
Puncture and impact injuries, acid burns or burns to the eye are less common causes of blindness, but they are all the more devastating.
This eye disease is also rare, but it can very quickly lead to blindness. The retina becomes detached from the eyeball. A warning sign are lightning bolts and zigzag lines in the eye. Inflammation of the vascular skin of the eye (uveitis) can also cost eyesight.
Alcohol and blindness
In some countries, such as Russia, people go blind after consuming hard liquor. The reason is that unprofessional distilling of schnapps produces dangerous methanol. This alcohol variant is actually an additive in solvents or antifreeze. When methanol is broken down in the body, poisonous by-products such as formaldehyde and formic acid are produced. Impaired eyesight is typical of methanol poisoning. The toxic breakdown products block the metabolism, the retina swells and visual information no longer reaches the brain. Ultimately, the toxins damage the optic nerve itself - then permanent blindness threatens.
Other acquired causes of blindness
There are other reasons for blindness in developing countries due to poor medical care. These include, for example, worm infestation in the eye (river blindness or onchocerciasis), chlamydial infection of the eye (trachoma) or a vitamin A deficiency that dries out the surface of the eye (keratomalacia or xerosis conjunctivae).
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