Leber’s congenital amaurosis is a hereditary disorder of the function of the retina of the eye. Primarily, a specific pigment epithelium located on the retina is affected by the impairment. The term of the disease is derived from the Greek word ‘amauros’, which means blind or dark. Leber’s congenital amaurosis is congenital and also includes various degenerative conditions that develop on the choroid of the eye.
What is Leber’s congenital amaurosis?
Basically, Leber’s congenital amaurosis is an inherited disorder. The disorder was first described in 1869 by physician Theodor von Leber. He also noted that the disease was clustered in closely related individuals and in this way discovered the genetic component of Leber’s congenital amaurosis. A characteristic feature of the disease is that patients are already born with visual impairments. In some cases, they are even completely blind from birth. In siblings, Leber’s congenital amaurosis also occurs with a probability of about 25 percent. In principle, approximately 10 percent of all cases of blindness are caused by Leber’s congenital amaurosis. Care should be taken not to confuse Leber’s congenital amaurosis with Leber’s hereditary optic atrophy. This is a genetic disease that usually affects the optic nerve. In principle, the term Leber’s congenital amaurosis summarizes a variety of so-called retinal-choroidal dystrophies. These occur because affected patients have a disorder of the pigment epithelium in the retina. As a result, the retina loses its function. In addition, the choroid of the eye degenerates. The number of affected individuals in Germany is estimated to be about 2,000.
Causes
The causes of Leber congenital amaurosis are largely understood in modern times. The disease is genetic and, in the majority of cases, is passed on to offspring in an autosomal recessive manner. Far less frequently, Leber’s congenital amaurosis is inherited in an autosomal-dominant manner. According to the current state of knowledge in medical research, the exact causes of the disease lie in diverse types of mutations. Fifteen subcategories of mutations and genetic defects have been identified. Frequently, homozygotes of certain genes are present that lead to the expression of Leber’s congenital amaurosis. For example, one potential cause is a defect on the RPE65 gene. As a consequence, a special enzyme is altered, which is very significant for the reconstruction of the substance rhodopsin. In addition, Leber’s congenital amaurosis is shown to occur more often in children from marriages between relatives.
Symptoms, complaints, and signs
Leber’s congenital amaurosis is usually associated with several symptoms. First, the visual acuity of affected patients is usually markedly reduced and the visual field is considerably limited. In the majority of cases, this leads to complete blindness. In addition, those affected often suffer from nystagmus in conjunction with so-called strabismus. There is also a low sensitivity to glare and hyperopia. In the later course of Leber’s congenital amaurosis, a clouding of the lens and a keratoglobus may develop. In numerous cases, the findings on the retina are not very noticeable at the onset of the disease. However, with time, the impairments on the pigment epithelium become more obvious. In the course of this, depigmentation also occurs, which resembles salt or pepper on imaging. The optic nerve may be affected by atrophy.
Diagnosis and course of the disease
If typical symptoms of Leber congenital amaurosis are seen, an appropriate specialist should be consulted as soon as possible. Especially in affected children, it is important not to wait to present to the physician. This is because the sooner therapy is started in young patients, the more favorable the course of the disease usually becomes. The first step is to take a patient’s medical history, which the attending physician performs together with the affected patient.The individual complaints, the person’s medical history and family connections are the focus of the analysis. In this way, the physician already obtains a range of important information that helps him to make the diagnosis. The typical clinical appearance finally indicates the presence of Leber’s congenital amaurosis. The disease can be diagnosed with certainty with the help of electroretinography. If a person suffers from Leber’s congenital amaurosis, this examination reveals relatively early absent stimuli. This also allows the disease to be differentiated from other hereditary atrophies of the optic nerves.
When should you see a doctor?
Leber’s congenital amaurosis is hereditary and is therefore usually diagnosed immediately after birth. Whether further visits to the doctor are necessary depends on the type and severity of the condition. If the child suffers from visual complaints, an ophthalmologist must be consulted in any case. If the symptoms are severe, medical advice must be sought immediately, because if left untreated, the patient may go completely blind. Persons who suffer from Leber’s congenital amaurosis themselves should have a genetic test performed if offspring are pending. Early diagnosis, preferably while the child is still in the womb, allows treatment to be initiated quickly. This significantly improves the chances of recovery for the child. If further visual disturbances or other complaints in the area of the retina and pupils occur during treatment, medical advice is required. Further contacts are the ophthalmologist, an internist and a specialist clinic for hereditary diseases. Children should also be closely monitored by a pediatrician. In case of complications, appropriate measures can then be taken quickly.
Treatment and therapy
For a long time, the medical community believed that Leber congenital amaurosis was not curable. Recently, however, studies have revealed new evidence of ways to successfully treat the disease. This involves injecting adenoviruses into the retina so that defective genes are replaced.
Outlook and prognosis
The prognosis of the disease depends on the extent of the disorders present. Researchers determined that the cause of Leber congenital amaurosis is due to a genetic defect. The challenge, therefore, is finding an appropriate treatment method. Due to legal requirements, physicians are not allowed to alter human genetics. Nevertheless, it has become apparent in recent years that there is a prospect of alleviating symptoms for some patients under certain conditions. According to initial studies, adenoviruses were successfully injected into the retina of patients with the disease. Vision was restored. This can significantly improve the patient’s quality of life. In some cases, it has been documented that a complete regeneration of vision occurred and was comparable to a healthy person. Nevertheless, this procedure is not used in every patient or does not generally lead to a successful therapy. Further studies are necessary and finally the examination of the legal applicability has to be done. It has to be taken into account that in case of an unsuccessful therapy the risks for secondary disorders are increased due to the emotional stress. In the case of an unfavorable course of the disease, a psychological disorder develops. This additionally reduces the patient’s quality of life and has a considerable influence on the further course of the disease.
Prevention
Leber congenital amaurosis represents a hereditary disease that is already present at birth. For this reason, there is no way to prevent the disease. Therefore, appropriate therapy is particularly important.
Aftercare
In this disease, there are few measures of aftercare available to the patient in most cases, since the disease cannot be completely cured and usually leads to complete blindness of the patient. Therefore, most people affected by this disease are dependent on the help of other people and their own family in order to still be able to cope with everyday life. Since this is a genetic disease, it is recommended for those affected to first undergo genetic testing and counseling if they wish to have children, in order to prevent the recurrence of the disease.The earlier a doctor is consulted, the better the further course of this disease usually is. If the blindness has already occurred in the children, they are dependent on intensive support in their lives so that they can continue to develop normally. In this context, loving conversations with the parents also have a positive effect on the further course and can prevent psychological complaints or even depression. Furthermore, no special measures of an aftercare are necessary or possible. As a rule, this disease also does not reduce the life expectancy of the affected person.
What you can do yourself
Patients with Leber’s congenital amaurosis have their independence and quality of life impaired by the disease. The typical limitations in visual function lead to various problems in everyday life and sometimes result in further physical and psychological suffering. Due to the reduced visual function, for example, some patients may neglect sports activities and their fitness suffers accordingly. With regard to psychological complaints, anxiety disorders or depression come into question, since the threat of blindness represents an enormous burden for many people. It is important to visit the ophthalmologist regularly so that he or she can detect relevant changes in the condition of the visual function at an early stage. If the patient’s blindness actually appears imminent, he or she redesigns his or her home to accommodate the visual impairment. The aim of the new facility is to make it easier for the blind person to find his way around and also to reduce the risk of accidents. Blind patients practice using a long cane in a school for the blind and, if necessary, learn Braille. Most of those affected also benefit from social contacts through which they experience support despite the disease. Blind people also come into question here. This is because patients often experience an increase in quality of life through interaction with other visually impaired people.