In medicine, there are many different types of visual impairment. Some are already congenital, others are acquired. In either case, low vision should be corrected to prevent further damage to the eye and provide a better quality of life for those affected.
What is low vision?
Schematic diagram showing the anatomy of the eye with myopia and after treatment. Click to enlarge. Low vision occurs when an eyeball is unable to image an object properly on the retina, or is no longer able to do so, and consequently the affected person is unable to perceive objects as someone with healthy vision would. Classic visual impairments are those in which affected persons can no longer see objects sharply. A distinction is made between hyperopia, commonly known as farsightedness, and myopia, commonly known as nearsightedness. In addition, there are also visual impairments in which those affected cannot distinguish between the colors red and green, the so-called color vision impairment, or can see poorly at night, the so-called night blindness or hemeralopia. Another possible visual impairment is double vision, also known as diplopia in technical jargon, in which those affected cannot see properly in three dimensions due to an incorrect eye position. In some cases, amblyopia also occurs when visual impairment is present even though the eye is organically completely healthy.
Causes
Low vision can have a variety of causes. Most visual impairments are congenital. To see sharply, the eye must focus light rays so that the focal point is exactly on the retina. The lens of the eye is therefore flexible so that it can focus the light rays as necessary to see a targeted object sharply. If an eyeball is too long or too short, or if the lens of the eye is too curved, the focal point shifts. In addition, age is also often a causative factor for visual impairment. With age, the flexibility of the eye lens decreases and objects at certain distances can then only be perceived blurred, this is also referred to as presbyopia. However, some visual impairments are also acquired and often arise from a subconscious effort to correct a genetic misalignment of the eyes, or to suppress the transmission of the image of a defective eye to the brain. Night blindness, on the other hand, can be both hereditary and otherwise acquired.
Diseases with this symptom
- Farsightedness
- Squint
- Myopia
- Red-green weakness
- Color blindness
- Night blindness
Diagnosis and course
Visual impairment has many more people today than a century ago. Only an eye test brings certainty, how it is about the efficiency of the eyes. Unlike presbyopia, most visual impairments develop in childhood. For this reason, children today are examined for possible visual impairments at an early age in order to correct them and prevent further damage. A doctor (e.g., an ophthalmologist) or an optometrist can diagnose whether short-sightedness or long-sightedness is present and how pronounced it is by determining the refractive power. The visual impairment is then corrected with a visual aid in the form of glasses or contact lenses. Color blindness or night blindness is tested using other methods. If visual impairments are not detected in childhood, they often become apparent in old age. When the flexibility of the eye lens decreases, those affected can no longer correct existing nearsightedness or farsightedness themselves and then notice a visual defect by themselves. In addition, poor vision is often accompanied by headaches or eye pain. Correction by means of a visual aid is possible without problems even in advancing age. Nevertheless, it is better to detect visual impairments at an early stage, since visual impairments can progress to some extent and, in the worst case, a malposition of the eyes and thus a further visual impairment can develop as a result of an untreated visual impairment. Particularly in the case of farsighted persons, there is a risk that an adjustment of the eye lens to the refractive power can lead to inward squinting. Amblyopia may develop after double vision.In myopic individuals, there is also a risk of detachment of the retina, which can lead to complete blindness of the eye. However, if a change in the retina is noticed early, it can be easily corrected surgically.
Complications
Low vision usually cannot be treated, meaning that symptoms can be eliminated in only a few circumstances. This includes, first and foremost, lasering of the eyes. If low vision occurs over time and is not treated, it will not improve, but in most cases will become more severe. Those who do not use glasses or contact lenses in spite of poor vision, unnecessarily strain the muscles of the eyes. This usually makes the visual impairment even stronger. Therefore, if visual impairment occurs, the patient must immediately request and use a visual aid. When using contact lenses, dry eyes are a common side effect. The rule here is: if possible, avoid contact lenses and prefer to wear glasses. Especially when sleeping, contact lenses should be removed beforehand. In laser eye surgery, complications occur only in extremely few cases. Most operations are successful and remove the visual defect. Those who do not wear a visual aid despite low vision often have unclear or blurred vision. This not infrequently leads to headaches or migraine attacks and balance problems.
When should you go to the doctor?
Although direct treatment by a doctor is not mandatory for low vision, it is highly advisable. As a rule, the patient’s vision deteriorates when he or she suffers from untreated low vision. Young people in particular should therefore always consult an ophthalmologist or optometrist if they have this symptom. The ophthalmologist should be consulted if other symptoms occur in addition to poor vision. These include, for example, pain in the eye or veil vision. These symptoms may be a disease of the eye, which must be examined. If the patient suffers from low vision alone, an optician can also be consulted to prescribe suitable glasses or contact lenses. Particularly in older age, poor vision is a common symptom. Children should see an ophthalmologist regularly, even without symptoms, for a check-up. In this way, any existing visual defects or visual weaknesses can be detected at an early stage and treated directly. In this way, consequential damage can be avoided. As a rule, a specialist can be consulted directly, a visit to the general practitioner is not necessary.
Treatment and therapy
Short-sightedness and long-sightedness can be corrected by glasses or contact lenses. In addition, it is nowadays also possible to restore vision surgically. This often involves using a laser to alter the refractive power of the eyes. The success of surgery depends on the strength and type of visual impairment and is not successful in all cases. To prevent diplopia or other visual impairment from developing into amblyopia, the healthy eye is usually masked for a longer period of time. This ensures that the vision of one eye is not suppressed until a visual impairment develops here. Color blindness cannot be treated so far, but there are tinted contact lenses or spectacle lenses with which those affected can see much more clearly, at least in daylight. Depending on the underlying causes of night blindness, it is treated differently. Night blindness caused by vitamin A deficiency can be corrected by administering vitamins. Night blindness with other causes is often not treatable and cannot be corrected by vision care.
Outlook and prognosis
The outlook for low vision is very difficult to predict and depends greatly on the cause of the low vision. If low vision is not treated or the eyes are not supported by a visual aid, the low vision usually increases and does not disappear on its own. If glasses are not used, the muscles of the eyes must work harder to see sharply. The strength of the muscles diminishes over time and the visual impairment increases. Therefore, a visual aid should always be used to compensate for a visual impairment. A visual impairment can also occur for a short time, for example during a migraine.In this case, the visual impairment disappears on its own when the migraine has subsided. It is possible to correct the visual impairment with the help of a laser. In this case, however, the patient must already be an adult so that the visual acuity does not change in the course of life. With this treatment, there are usually no complications or further discomfort. In older age, visual impairment occurs preferentially, although it is a common symptom that usually cannot be avoided.
Prevention
Night blindness resulting from a deficiency of vitamin A can be prevented with a healthy diet containing sufficient vitamin A. However, because most visual deficiencies have genetic causes, they cannot be countered by specific prophylactic measures. However, if visual impairments such as farsightedness, nearsightedness or double vision are detected early and corrected immediately, further visual impairments that may develop from them can be averted. It is therefore advisable to have children’s eyes examined at an early stage in order to detect any visual deficiencies and correct them with vision aids. It is controversial whether external, unfavorable influences, such as reading in poor light, can lead to visual impairment. However, to prevent this risk, poor image quality should not be projected onto the retina and, for example, reading should only be done in sufficient light and the eyes should be allowed time to recover after particular exertion.
What you can do yourself
It is usually not possible to treat low vision at home. In many cases, medical treatment is also not possible, so the patient must live with the visual impairment for the rest of his or her life. In case of night blindness, a healthy diet can help. In this case, the body needs vitamin A in particular and must be supplied with it. For this purpose, a healthy lifestyle with the consumption of fruits and vegetables is recommended. As a rule, unnecessary efforts of the eyes should be avoided. This includes working at a monitor for long periods of time or reading content in poor light. Likewise, if you have poor vision, you should always wear a visual aid. This can be either glasses or contact lenses. If the visual aid is not worn, the muscles in the eye have to work hard to see sharply. This can increase the visual impairment. Therefore, it is advisable to always wear the visual aid when it is necessary. Regular visits to the eye doctor and optometrist are also recommended. The earlier the visual impairment is detected, the better it can be treated. An ophthalmologist can likewise provide information about possible surgical interventions.
