What is a visual impairment (also called “low vision“)?

In Germany, there are legal definitions of visual impairment and blindness. They are defined by the national law and are classified by degree of disability using percentages. For example, someone who can only recognize an object from a distance of 10 meters that a person with normal vision can recognize from a distance of 100 meters has a visual acuity of 10%, or 0.1. A visual acuity of less than 0.05 is legally considered to be a “severe” visual impairment. If visual acuity is 0.02 or lower, the person is considered legally blind.

The legally blind designation also applies if the person’s visual field is restricted to a maximum of 5 degrees of visual angle. They may still have some residual vision, such as being able to see coarse shapes (for example, large letters) or light and dark. The most frequent cases are those in which the person has visual field defects, which means parts of the visual world are missing. In this case, the person can be considered blind even if they still have good visual acuity in the central part of their visual field.

When a visually impaired person reaches adulthood at the age of 18, according to German reimbursement codes, they are only entitled to reimbursement for visual aid devices (e.g., reading devices) if they suffer from a visual impairment or from blindness in both eyes that corresponds to level 1 of the classification recommended by the World Health Organization (WHO). This is the case even when their visual acuity can only be corrected to 0.3 to 0.1 with eyeglasses. This regulation is relevant for health-insured people who are almost blind or completely blind in both eyes or those who are blind in one eye and have very limited vision in the other eye.

B1 to B3 classifications of visual impairments are only used for active athletes who participate in sports such as para athletics, blind soccer, and para rowing. Visually impaired athletes are classified exclusively by an eye doctor (ophthalmologist) and are then assigned to the appropriate competition (starting) class. The starting class B1 is only for fully blind athletes who do not have any light sensation. B2 athletes score low in a visual test, and B3 athletes are considered visually impaired. The regulations are very strict. The visual acuity of the better eye with the best possible correction is used when assigning an athlete to their starting class.

Visual impairments manifest themselves in a wide variety of ways: visual field limitations (“tube” or “tunnel” vision), night blindness, color vision deficits, visual field loss, glare sensitivity, or severe vision limitations. There is also variety in how visual impairments are experienced, as patients with similar diagnoses can have different kinds of vision loss. And people who suffer from the same eye disease may have the same objectively measured visual abilities yet feel significantly different as far as how they perceive things subjectively and how they respond to the loss emotionally. Accordingly, their ability to cope with their disability can differ as well.

Some people can cope well with their limitations or even compensate for them. But others hang on to the belief that they only can be happy and satisfied if they can see “normally” again. They likely will cope poorly with their visual impairment. Their dark path of thinking may lead to disappointment, anxiety, grief, or anger, and it can make things worse and even make the disease progress faster.

In the course of a lifetime, the visual system can be disturbed by any of a number of issues, whether they are genetic or due to an accident or a disease. The main causes of visual impairment are considered to be the classic eye diseases such as cataract, diabetic retinopathy, macular degeneration (AMD), and glaucoma, which can slowly progress to visual impairment and even blindness. Neurological diseases, such as those that can occur after a stroke (apoplexy, also known as cerebral infarction or cerebral stroke), a traumatic brain injury, or a tumor, also often lead to vision loss.

There are around 37 million people worldwide who are blind. Of these, 90% live in so-called developing countries. Three-quarters of their diseases could be preventable, because cataract is considered the most common cause of blindness, followed by glaucoma and age-related macular degeneration (AMD).

The term “glaucoma” summarizes the diseases of the eye that are associated with increased intraocular pressure or blood flow regulation problems. Eventually, if left untreated for long periods of time, this condition can lead to blindness. However, complete blindness (black blindness) is very rare in developed countries.

More information about glaucoma can be found here.

Age-related macular degeneration (AMD) is a degenerative disease of the macula in the retina of the eye, also called the yellow spot, which is the part of the retina that is important for central (high-acuity) vision. AMD occurs mainly starting at age of 65, with women and men being equally affected. It leads to a loss of vision in the central area of the retina that can slowly progress. The peripheral part of the visual field is usually preserved.

AMD is one of the most common causes of blindness. Possible triggers of the disease include genetic predisposition, nicotine abuse, as well as intense sun exposure or malnutrition.

More information about age-related macular degeneration can be found here.

In retinopathy, the retina with its photoreceptors is no longer supplied with sufficient blood flow, which usually leads to a gradual loss of vision.

Here you can find more information about diabetic retinopathy.

Retinitis pigmentosa (RP) is a largely incurable disease that causes retinal degeneration. In most cases it is inherited.

Here you can find more information about retinitis pigmentosa.

Any disorder of, injury to, or disruption of the visual system can cause blindness, and the type of vision loss depends on where the damage occurs: the eye muscles, cornea, lens, retina, optic nerve, or brain. These disorders can be congenital, such as in eye malformations, or hereditary diseases. Other kinds of visual impairments can be acquired over the course of a life span. In addition to diseases such as age-related macular degeneration, diabetic retinopathy, and glaucoma, other common causes of blindness are cataract, retinal detachment, infections, and so-called vascular processes such as thrombosis or embolism. Injuries (traumas) to the eye, optic nerve, or brain can lead to different kinds of visual impairment or blindness. Rare cases of blindness have also been reported after back surgery, methanol poisoning, and pregnancy, and as side effects of COVID-19 infections or vaccinations, and even certain medications.

Medical therapies are always guided by the cause of the visual impairment or vision loss. For example, a cataract is treatable with surgery. But for all other preventable causes of blindness, detecting them early and initiating appropriate treatments, such as eyedrops for glaucoma, is the best course of action.

Treatment options for visual impairments depend on the underlying disease. The more advanced the visual impairment, the more attention is paid to rehabilitation. This is intended to enable blind and severely visually impaired people to continue to live independently. There are many visual aid devices on the market, including apps and accessibility functions in smartphones.

More information about individual treatment options for each disease can be found in our review articles on age-related macular degeneration, diabetic retinopathy, and glaucoma.

Vision loss is partially reversible with SAVIR therapy. This therapy uses small microcurrent pulses to improve blood flow in the eye and brain, to reactivate “dormant” nerve cells so that the remaining visual stimuli can be better processed. Microcurrent treatment can significantly improve the vision of patients suffering from various diseases such as age-related macular degeneration, diabetic retinopathy, amblyopia, or glaucoma.

In a clinical trial, 82 patients with visual impairments caused by optic nerve damage were treated for 10 days with either microcurrent (SAVIR therapy) or a placebo therapy. To deliver the microcurrent treatment, electrodes were attached near the eyes to administer very mild current pulses via the electrodes for 40 minutes daily. After only 10 days of microcurrent therapy, visual performance improved significantly in two-thirds of the study participants, with the neuronal network of their brains recovering to partially restore their vision.

This could be explained by improved blood flow to the eyes and brain. For example, the visual cortex in the back of the head was again able to exchange signals with the frontal cortex in the forehead areas to generate meaningful images from the visual impulses of the eyes. Although the damage to the patients’ optic nerves had previously been considered irreparable, as a result of the treatment, patients were able to see better again. The therapy had simply reactivated “dormant” neurons.

SAVIR therapy has very few risks and side effects. In more than 2,000 patient treatments, not a single serious adverse event has been observed. The current impulses are much lower than those of a heart pacemaker, and are so weak that they are hardly felt on the skin. Patients may notice brief flashes of light when their eyes are closed during treatment.

Depending on the degree of a patient’s visual impairment, visual aids (glasses) may also be used. They must be individually adapted to individual patients by an optician or a vision rehabilitation specialist. Contrast is also an important factor to be considered. For example, the rooms, furniture, and other household objects of visually impaired people should be rich in contrast. High contrast makes it easier for them to find their way around and manage daily tasks. For example, a white cup on a white table is hard to see, so the use of a black cup is much better. Uniform and glare-free light sources and spot lamps provide additional support. For these, cold light with high-luminosity halogen lamps are preferable.

There are currently 145,000 blind people in Germany alone, with around 10,000 new cases of blindness every year. Of those affected, 60% are over 60 years old, and 38% are over 80. Visual impairments are not always recognized immediately by outsiders, because even people who are blind by definition often leave the house without a yellow armband or a cane for the blind.

Blind people may be able to read with a magnifying glass or operate a computer with the help of a special device that enlarges the letters. Many visually impaired people are very mobile and manage well in everyday life; they may not even consider themselves to be “blind.” However, for some activities they need assistance. For example, the visually impaired can find it difficult to decipher handwriting. A thick black pen on white paper and block letters should be used to write them messages. Many things that are easy for normally sighted people require a great deal of concentration for the visually impaired. Recognizing faces or gestures, looking someone in the eye — these things can be difficult or impossible. This should be kept in mind when dealing with the visually impaired.

Simulation glasses allow sighted people to experience what it’s like to be a blind person. They come in a variety of styles that simulate different eye conditions and visual impairments.