In night blindness, medically called hemeralopia, vision at dusk is impaired. This is due to a functional weakness of the rods. These are the sensory cells in the retina that enable vision in poor light conditions.
What is night blindness?
Night blindness can be congenital, but it can also be caused by a disease such as diabetes or a vitamin A deficiency. From this depends on how night blindness progresses. In almost all cases, night blindness cannot be cured. See psyknowhow for Leptospirosis Explained.
In a narrower sense, night blindness means that you can no longer see anything at all at night or in twilight. This is very rare, most patients affected by night blindness simply have poorer vision at night. In both cases, however, night blindness is spoken of.
The cause of night blindness is always a disturbance of the rods. These sensory cells in the retina allow us to see at dusk. Such a dysfunction of the rods can be triggered by many different causes.
Therefore, if you have night blindness, it makes sense to be examined by an ophthalmologist. Vitamin A deficiency is very rare in industrialized countries. Vitamin A is necessary for seeing light and dark and leads to impaired vision in the dark if it is present in insufficient amounts.
A vitamin A deficiency can occur, among other things, if not enough foods are eaten that contain the vitamin or if adequate intake is not possible due to a stomach or intestinal disease.
Congenital diseases are far more frequently responsible for night blindness. For some people, the chopsticks just don’t work as well. This form of night blindness is often accompanied by nearsightedness and trembling of the eyes (nystagmus). But the rather rare retinopathy pigmentosa can also lead to night blindness.
In this disease, the sensory cells of the retina are attacked by endogenous processes and gradually lose their function. Other physical illnesses such as diabetes can also cause night blindness if the fine vessels in the eye are damaged by diabetes.
The vision problems that a cataract (clouding of the lens) brings with it are not night blindness in the true sense. Patients with cataracts simply notice more in the twilight that their vision is blurry and they are blinded by the incoming light.
By the way, it’s normal if you don’t see anything for the first few minutes after coming from a bright room to a dark room. The eye needs a few minutes to adapt to changing light conditions.
Symptoms, Ailments & Signs
With night blindness, there are problems with vision in poor light conditions. The eye is no longer able to adapt to twilight or darkness and reacts to rapid changes in brightness with visual problems and blindness. Patients often notice a gradual deterioration in night vision, often with symptoms such as eye tremors or myopia.
If night blindness is caused by a disease of the retina (e.g. retinopathy pigmentosa), visual field defects also occur. As the disease progresses, complete blindness can occur in one or both eyes. When vitamin A deficiency is the cause, hemeralopia is often accompanied by very dry eyes and itching or pain.
In addition, other visual disorders such as color vision disorders and double vision appear. Night blindness symptoms can be congenital or the result of an illness or accident. It mainly affects people between the ages of 30 and 50. The hereditary form develops shortly after birth.
Already in the first two years of life, the affected children suffer from short-sightedness, visual field defects and visual problems in restricted lighting conditions. A progressive course means that in individual cases the sufferers become partially or completely blind before they reach adulthood.
Diagnosis & History
To diagnose night blindness, the ophthalmologist first examines the dark adaptation of the eyes, ie how well and quickly your eyes can adapt to changing light conditions. An adaptometer is used for this. In addition to dark adaptation, this device can also be used to measure how sensitive to glare and how short-sighted you are in the twilight.
The causes of night blindness are then sought. An electroretinogram is used for this purpose. With this device, the functionality of the sensory cells in the eye can be checked: the rods, which are responsible for seeing at dusk and the cones, the sensory cells for color vision.
The course of night blindness depends on its cause. If night blindness was inherited from parents, night blindness usually does not get worse over time. Retinitis pigmentosa, on the other hand, gradually leads to greater visual impairment, which also affects night blindness.
Night blindness in the narrower sense is the complete functional failure of the rod-shaped photoreceptors, the greatest density of which is on the retina outside the macula, the place of sharp color vision. The rods are characterized by strong light sensitivity and high sensitivity to moving objects, but do not convey any color vision. Most of the time, however, night blindness is just limited night vision, which is particularly noticeable through an unpleasantly increased sensitivity to glare when driving at night.
If the night blindness is due to a genetically determined misalignment of the rods, the limited vision at dusk and at night does not change further in the further course. If the night blindness is acquired, the further course depends on the cause. If it is just a vitamin A deficiency due to an unbalanced diet or because the absorption capacity of the intestinal tract is limited due to an intestinal disease, the symptoms improve when the metabolism can again have a sufficient amount of vitamin A at its disposal.
If the problems are due to damage to the vascular system in the retina, which can be caused, for example, by too high a sugar concentration in the blood due to undiagnosed type 2 diabetes, the prognosis is unfavorable if the disease continues to be ignored and not treated. Another causal factor of night blindness can also be a genetically determined retinopathy pigmentosa, which is usually associated with a very slow progression of the disease.
When should you go to the doctor?
Decreased vision during the dark is a natural process that does not need to be examined and treated. However, if further symptoms occur or if the inability to see begins at dusk, a doctor should be consulted for a check-up. If your own vision differs in direct comparison to other people, you should see a doctor.
If the surrounding objects or other people can only be perceived dimly or blurred, a doctor’s check-up is necessary. Tremors in the eyes, pain in the eye area or headaches are signs of an existing irregularity. If there are more accidents or falls due to reduced vision, a doctor’s visit is recommended. Severe short-sightedness or the feeling of blindness with decreasing light influences must be examined and clarified. Losses on the face are of particular concern as they are a clear sign of an existing condition.
If, in addition to the physical impairments, there are also emotional or psychological irregularities, a doctor should also be consulted. Behavioral problems, aggressive tendencies, anger and withdrawal from participation in social life are unusual. If there is a depressive appearance, mood swings or an increased potential for conflict, the observations should be discussed with a doctor.
Treatment & Therapy
Treatment for night blindness depends on the diagnosis. If the night blindness is congenital, unfortunately no promising therapy method is known.
Damage to the fine vascular system of the eye and the retina, e.g. B. by diabetes, can not be reversed so far.
When night blindness is caused by vitamin A deficiency in the diet or a gastrointestinal disease, the twilight vision problems usually stop when the underlying problem is corrected.
Outlook & Forecast
Night blindness itself does not shorten lifespan. However, the quality of life often suffers. Affected people find it much harder to find their way around in the dark. This can necessitate a need for help, since the disappearance of sunlight is an everyday phenomenon.
In principle, night blindness remains permanent after the first appearance. Most patients experience neither improvement nor deterioration. So far, medicine has had its limits. While a simple ametropia can easily be corrected with a visual aid, this is not the case with night blindness. In some cases, night blindness means that those affected cannot practice certain professions.
There are better prospects for congenital inpatient night blindness. This form heals in many patients. Courses in which a vitamin deficiency causes the visual impairment can also be successfully treated. On the other hand, people with retinitis pigmentosa must reckon with a deterioration. Even blindness is possible.
The diagnosis “post-blindness” therefore leads to a differentiated prognosis. While a shortened life expectancy is not foreseeable, there are usually lifelong restrictions in everyday life and at work. Overall, a mixed outlook can be formulated.
Preventing night blindness is usually impossible. Congenital forms of night blindness, such as rod weakness or pigmentary retinopathy, cannot be prevented. In the case of diabetes, an adapted lifestyle and well-controlled blood sugar often help to avoid damage to the vascular system, including that of the retina. Vegetarians and vegans should make sure that they frequently eat vegetables that contain vitamin A, e.g. E.g. peppers, tomatoes and carrots.
The extent to which follow-up care is necessary depends on the chances of recovery. Especially people who have suffered from night blindness since birth have to deal with the disease for the rest of their lives. There is no prospect of healing. They have no choice but to seek outside help when it is dark and generally avoid dark surroundings. Psychological support can be indicated selectively.
Cases in which night blindness has developed in the course of life are usually different. Then regular checks are indicated. Because there is a risk that the eyesight will deteriorate even further. An annual visit to the ophthalmologist prevents complications.
In addition to an anamnesis, an eye examination takes place, in which the doctor determines the time it takes for the eyes to adjust to the darkness and the perceptible light intensity. Clear comparisons to the past can be drawn from this information and general investigations into visual acuity and visual field. Necessary treatments can be initiated in good time. The diagnosis of night blindness brings with it some demands on the patient himself. The risk of injury in road traffic should not be underestimated with night blindness.
You can do that yourself
There are no home remedies available for people who are night blind. Natural remedies such as blueberry extracts are controversial. The additional intake of vitamin A is only partially successful. Without a medical diagnosis, it is strongly discouraged to self-medicate with alternative methods.
The reduced vision in poor light causes limitations in everyday life. These have to be accepted and dealt with. Depending on the severity of the symptoms, safety goggles with filters prevent those affected from feeling dazzled by light. However, these glasses do not correct or improve vision. Those who suffer from real night blindness do not drive a car for the sake of themselves and others and use public transport or car services. Flashlights help with daily walking in the dark. These ideally have an even light cone to make it easier to see. Digital language assistants, who explain the way via smartphone, help with orientation.
Self-help groups and associations support those affected. They offer advice on any question. The exchange with other affected people helps to overcome everyday hurdles. The self-help association Pro Retina specifically addresses people with retinal diseases and supports people affected by night blindness.