Best’s disease is a genetically inherited, chronic eye disease that causes the death of cells in the retina of both eyes. Typically, Best disease manifests in adolescence.
What is Best disease?
The eye disease is named after the Dresden ophthalmologist Dr. med. Friedrich Best, who first described the clinical picture named after him in 1905. Best’s disease is a rare eye disease and is not always immediately recognized by ophthalmologists when symptoms first appear. Best’s disease is also known by the medical terms juvenile macular dystrophy or vitelliform macular dystrophy. In the center of the retina of each eye is the so-called macula, i.e. the area of sharpest vision. It is precisely this important area that is affected in Best’s disease, where the degeneration of photoreceptors can lead to a significant impairment of vision. Best’s disease first appears in adolescence, usually by the age of 20. The predisposition to develop macular degeneration clearly depends on the presence of a certain gene segment of the DNA. If the disease breaks out due to activation of this gene sequence, there is a more or less pronounced cell death in the area of sharpest vision.
Causes
Best’s disease is congenital; therefore, once the onset of the disease has occurred, its progression can only be stopped symptomatically. The mode of inheritance responsible for the disease is autosomal recessive, and the gene segment on the DNA responsible for the onset of Best disease has its own name, the Best-1 gene. This gene, in turn, is responsible for the blueprint of a specific protein called bestrophin 1. The presence of this protein in the retina of the eye ensures membrane conductance as well as nourishment and removal of toxins from the photoreceptors. As soon as Best’s disease breaks out, this sensitive mechanism is disturbed in such a way that more and more toxins accumulate at the site of sharpest vision. Over time, these harmful degradation products take on a typical yellowish coloration and are deposited between the photoreceptors. These yellowish deposits are the most important diagnostic criterion for ophthalmologists to detect Best’s disease when it reaches a certain degree of severity.
Symptoms, complaints, and signs
In Germany, no more than 4000 people are estimated to be affected by genetically determined juvenile macular dystrophy. Only a few isolated cases have been documented where the disease was first diagnosed in people beyond the age of 50. Initial symptoms may be relatively nonspecific in the form of barely noticeable visual loss. Since visual acuity is hardly affected at first, those affected do not usually seek medical help at this stage. Only in the further course can a massive loss of visual acuity occur. The late stage of Best’s disease also harbors risks with regard to additional loss of visual acuity. The cause is an atypical vascularization in the choroid of both eyeballs. If left untreated, Best’s disease can also lead to total loss of vision in both eyes. This is why early diagnosis and adequate symptomatic therapy are so important and helpful.
Diagnosis and progression
The most important diagnostic criterion is a yellowish protrusion recognizable in the area of the sharpest vision, macula, as a product of atypical deposition of lipofuscin. This protrusion resembles an egg yolk in shape and color, hence the Latin name vitelliform macular dystrophy. Because this disease appears early, it is sometimes detected during screening examinations of school children or young adolescents without their already showing first symptoms. Electrooculograms and the so-called Ganzfeld electroretinogram are also used to confirm the diagnosis. The course of Best’s disease is always chronic and slowly progressive if symptomatic therapy is not given in time.
Complications
No proven method of treatment currently exists for Best disease. Best disease usually develops at a young age because it is inherited and very rarely occurs suddenly. The consequence of Best’s disease is a severely reduced visual acuity, which in the worst case can turn into complete blindness.This transition can hardly be prevented, today there are no scientifically proven methods to treat this symptom. It is recommended to take more vitamin A and lutein, but the effectiveness of these substances has not been proven. The lutein is mainly found in green vegetables. In Best’s disease, the affected person should also wear sunglasses with UV protection, and not to further damage the retina. If the retina continues to be damaged, this will lead to further vision loss. Magnifying vision aids can be used so that the patient can see again. No improvement of the disease is to be expected, but it does not necessarily have to increase either. It is possible, for example, that the visual impairment will not change or increase over the course of a person’s life. Since there is no treatment option, there may be no complications of Best’s disease treatment here for the time being.
When should you see a doctor?
With Best’s disease, a doctor should always be consulted when, for no particular reason, the affected person experiences visual discomfort or decreased vision. In many cases, these complaints occur suddenly and are not associated with any particular reason. Especially in case of severe loss of vision, a doctor should be consulted, because in the worst case, a complete loss of vision due to Best’s disease can occur. If Best’s disease is diagnosed at a late stage, direct treatment of this disease is usually no longer possible. Especially in children, vision should be checked regularly. A doctor should also be consulted in case of small changes. Best’s disease can be diagnosed and treated by an ophthalmologist. If diagnosed early, symptoms and complete loss of vision can be limited and prevented. It is not uncommon for Best’s disease to cause psychological distress or depression. In this case, a psychologist should be consulted. Likewise, contact with other patients can help against depression.
Treatment and therapy
A causal, i.e., cause-related therapy of Best’s disease is not possible to date. However, the course of the disease can be considerably mitigated and slowed down by symptomatic measures. Patients have to undergo ophthalmologic check-ups several times a year, even if the course of the disease could supposedly be stopped. For symptomatic therapy of the disease, anti-inflammatory infusions or injections with the active ingredients cortisone or triamcinolone are administered. The physician must decide on the duration and dosage of treatment on an individual basis according to the severity and course of the disease. Often, therapy is required for years and decades, which is why undesirable side effects can then also occur as a result of the medication administered. For many patients, coping with the disease also involves contact with other sufferers, usually in the form of self-help groups. In order to further optimize treatment options for those affected by Best’s disease, there is still a considerable need for research. Only regular visits to the doctor ensure timely information for those affected as new therapies become known.
Outlook and prognosis
The prognosis in Best disease does not allow for a cure due to the genetic cause. However, the prognosis is highly variable with respect to progression. For example, some affected individuals may experience severe vision loss within a few years, while others may live for decades without severe impairment. There are various measures of varying effectiveness that can presumably slow down the course of Best’s disease. For example, to protect the structures in the eye, it is recommended to avoid situations with the risk of strong light exposure. Likewise, wearing edge-filtering lenses (filter blue light from incoming light) is recommended. Medicinal means mainly include methods to treat occurring inflammations in the context of Best’s disease. These are usually permanent therapies that can also lead to side effects. Nevertheless, they are necessary to protect the remaining photoreceptors. Whether and to what extent a certain diet has an influence on the course of the disease (especially in the early stages) is under discussion. The influence of lutein (contained in green vegetables) and vitamin A is discussed. Most of those affected do not go completely blind, but their vision is severely limited.Appropriate magnifiers and custom-made products, which allow a sharp image in a magnified sub-area, maintain the ability to live a normal life as much as possible.
Prevention
Direct prevention of Best disease is impossible due to the genetic cause of the disease. To prevent the disease from progressing and to preserve vision for as long as possible, the eyes should always be well protected from excessive exposure to light. To this end, Best’s disease patients are recommended to wear edge filter lenses, which filter out the blue-wave light component from the total light spectrum. Furthermore, the ability of patients with Best’s disease to communicate in everyday life can be significantly improved. To achieve this goal, patients are encouraged to use individually fitted magnifying visual aids, including optical magnifiers, for example, when working on the computer or reading.
Prevention
Unfortunately, there is no follow-up care available for Best’s disease. Since the disease is hereditary, it also cannot be treated causally and can only be partially limited. In the worst case, the affected person suffers complete blindness, which is irreversible and can no longer be treated. The patient should always use his visual aid. The earlier Best’s disease is diagnosed and treated, the greater the likelihood of avoiding vision loss. Those affected are often dependent on the help of other people in their daily lives. Specially made glasses and magnifying glasses can also help them to cope with everyday life. Likewise, a healthy diet can alleviate the course of the disease and also stop blindness. Those affected should always wear sunglasses with a UV filter when exposed to strong sunlight and regularly visit an ophthalmologist or optician. This can also prevent further complications. Contact with other Best’s disease sufferers is also very helpful, as it can lead to an exchange of information, which can also prevent psychological complaints. Best’s disease does not negatively affect the patient’s life expectancy.
This is what you can do yourself
No conventional medical treatment options currently exist for Best’s disease. However, specialists in hereditary diseases recommend some self-help measures and tips that can help alleviate the symptoms of the disease. In principle, a healthy diet with sufficient vitamins and fiber is recommended. Especially green vegetables can help against the visual impairment due to the lutein they contain. Symptomatically, appropriate UV protection through sunglasses and care products also helps. It is also advisable for those affected to talk to their ophthalmologist regularly. Possibly a magnifying visual aid reduces the symptoms or the retina can be protected by a special contact lens. Since, despite all these measures, there is no long-term treatment option for Best’s disease, it is advisable for those affected to visit a self-help group. Valuable tips on dealing with Best’s disease can be exchanged in conversation with other sufferers. The responsible physician can name further contacts and make the sometimes difficult course of the disease easier for those affected. Finally, the necessary precautions for a possible blindness should be taken. Depending on the severity of the disease, it may make sense to purchase the necessary aids at an early stage and to equip the home for the disabled.