Impaired Vision

Impaired vision is associated with a variety of symptoms. Find out which are the most common causes of vision disorders and when you need to see a doctor.

Visual disturbances include a number of very different symptoms: Some see flashes, zigzag lines, swarms of mosquitoes, flicker, veil or fog in front of their eyes, while others experience double vision or visual field loss. Visual disturbances can be temporary and harmless, for example in circulatory problems. Sometimes, however, they are caused by serious illnesses that require treatment. For example, a stroke or a retinal detachment due to impaired vision – quick action is required and you must call an emergency doctor immediately!

The technical term “visual disturbances” is unspecific. Doctors understand by it all changes of the optical perception, thus of the sight. And regardless of the cause. Visual disturbances can develop slowly or suddenly. Some have sudden visual disturbances in one eye, while others have visual disturbances in both eyes at the same time.

Children’s vision is also prone to disturbance. Visual acuity does not develop normally if ametropia (farsightedness, nearsightedness) or strabismus remain untreated. Sudden visual disturbances in children tend to indicate eye diseases (e.g. inflammation) or other diseases in the body, such as migraines. Always have your child’s vision problems checked by a doctor!

The causes of vision disorders are extremely varied. They range from non-hazardous circulatory problems, such as those caused by a change in the weather, to eye injuries and a wide variety of illnesses. These can affect the eye itself, but can also take place in a completely different part of the body and then affect vision. Examples are diabetes, high blood pressure or liver damage due to excessive alcohol consumption.

Types of vision disorders and symptoms

Impaired vision can be associated with a variety of symptoms – from flashes of light to blurred vision and flickering eyes. Sometimes the symptoms are harmless, temporary and disappear by themselves, for example in circulatory disorders. In other cases, it is better to take the symptoms of vision problems seriously and act quickly – because serious illnesses can be the cause. Doctors know different types of vision disorders and symptoms. The most important at a glance!

Color vision defect / color blindness

Ophthalmologists summarise colour weakness and colour blindness under colour vision defects. In the case of colour deficiency, certain light-sensitive cells in the retina – the cones – do not function sufficiently. Color blindness means that one or more types of cones are missing in the retina – people affected can no longer see certain colors.

The worst form is complete colour blindness. This vision disorder means seeing the world in grey. A very common phenomenon is congenital red-green deficiency or colloquial red-green blindness – almost only men suffer from it. Diseases such as glaucoma, diabetes or Alzheimer’s disease also weaken the function of the cones or cause them to fail completely – then colour blindness is acquired.

Night blindness

Some people only have vision problems in the dark. The cause of night blindness (nyctalopia) lies in the second type of light sensory cells in the retina: the rods. They can distinguish between light and dark and ensure that a person can see well at dusk and at night. The rods are active even at very low light intensities. If they do not function sufficiently or even fail completely, people with night blindness do not see much or nothing at all in darkness. It is difficult for them to orient themselves.

Behind the inherited night blindness can be the eye disease retinitis pigmentosa. First the rods, later also the cones for colour vision gradually lose their function. If night blindness develops only in the course of life, retinal detachment or a vitamin A deficiency can be to blame. However, the latter is almost non-existent in industrialized countries with good medical and food supplies.

Flickering eyes, flashes of light, zigzag lines

Some people with impaired vision perceive light phenomena such as lightning, zigzag lines and flickering eyes. Doctors speak of “photopsies”. Such light phenomena are frequent companions for certain diseases, for example migraine and epilepsy. Eye migraine (ophthalmic migraine) also often leads to flickering eyes, flashes of light and restrictions in the visual field. In contrast to migraine, headaches are only sometimes added and are less severe. Eye migraine is a special form of migraine.

In most cases, sudden visual disturbances such as flickering in front of the eyes disappear on their own. If not, be careful! Because the retina can become detached or the vitreous body can lift off – then complete blindness threatens! Elderly people in particular are threatened by vitreous detachment because it shrinks over the course of their lives. If you have flickering eyes for a long time, have yourself immediately driven to the emergency room – but never drive the car yourself!

Double pictures (diplopia)

Visual disturbances in the form of double images are probably familiar to most people who have been exposed to too much alcohol. However, eye diseases and other diseases can also be responsible for double vision. Examples are disorders of the eye muscles, certain cranial nerves or the autoimmune disease multiple sclerosis. If the double images appear only on one eye (monocular diplopia), this may be due to corneal curvature or cataract.

Field of vision deficits (scotomas)

A visual field loss means that a person no longer perceives the same size of space as before – the visual field is restricted, narrowed, and the visual acuity in this area reduced. Visual field deficits are visual disturbances that can affect the middle region, but also the edges (tunnel vision).

There are various triggers for the restricted visual field. Examples are cataract, glaucoma, macular degeneration, optic neuritis or retinal damage. Many of these eye diseases can lead to blindness. Other diseases such as strokes, eye and brain injuries or tumours are also associated with visual field deficits.

Blurred vision

One of the most common visual disturbances is when people suddenly see blurred. They see blurred and describe the visual disturbance as if they were perceiving their environment through a fog or veil. The reasons can be overstrained eyes, defective vision (e.g. short-sightedness or long-sightedness), glaucoma or, in the worst case, retinal detachment. In the latter case, you must act quickly because blindness is imminent!

Flying Mosquitoes

If small threads or dots suddenly fly over the visual field, this is not always an immediate cause for concern. The “flying mosquitoes” or French “mouches volantes” are usually harmless and are caused by turbidity in the vitreous. These cast shadows on the retina, which you perceive as threads or streaks. They occur more frequently with severe nearsightedness and increasing age. However, if they severely affect your vision, always consult an ophthalmologist. Because behind the flying mosquitoes could also be a vitreous detachment or retinal detachment.