A sharp bilateral decrease in visual acuity may indicate the development of a dangerous pathology - Leber optic neuropathy. This disease most often affects young males. Let's consider the causes of pathology, symptoms and features of therapy in the article.
For the first time, cases of a disease in which visual acuity rapidly decreases due to atrophy of the optic nerve were described in 1871 by Theodor Leber. The scientist observed the development of pathology in young people from several related families, which indicated a hereditary cause of the disease. The mechanism of inheritance of the disease was carefully studied, so it was possible to prove that the pathology is transmitted through the maternal line mainly to men.
Until now, the nature of the disease has not been studied well enough to find effective treatments for such a disease. Currently, treatment of patients consists of maintenance therapy, but from time to time groups of scientists present new gene therapy techniques for clinical trials, which, of course, gives hope to people with a similar diagnosis.
Leber's optic neuropathy: symptoms, treatment of the disease
Any visual impairment that rapidly progresses must be carefully studied and comprehensively diagnosed. Leber's optic neuropathy is rarely accompanied by malaise characteristic of neurological diseases, and vision declines quickly, sometimes not even within a few months, but within two to three weeks. With such acuity, vision cannot be checked using Sivtsev’s table, because a person simply does not see the signs, so they use hardware diagnostics and the “counting fingers” method at a certain distance from the patient’s face. The peculiarity of the disease is that the optic nerve is affected due to a gene mutation. An excess amount of toxic oxygen molecules is produced, which negatively affects the condition of nerve cells and vision decreases.
Leber's optic neuropathy - symptoms and features of the disease:
- young age of patients - 18-35 years;
- the disease develops more often in men;
- rapid unilateral and then bilateral vision loss;
- visual acuity decreases over several weeks;
- violation of color perception of red and green colors;
- the pathology may be accompanied by symptoms inherent in mitochondrial diseases (convulsions, cardiac conduction disturbances).
With Leber optic nerve atrophy, most often the process of disease development begins in one eye, but there are often cases when two eyes are affected at once. Central vision is constantly decreasing. This is due to the gradual death of cells in the optic nerve, which transmits image information to the brain. Sometimes the disease may be accompanied by symptoms characteristic of neurological diseases. In this case, the sick person suffers from dystonia, tremor, and ataxia. Less often, at the beginning of the development of pathology, a person notices sparks, spots, bright flashes before the eyes.
How is Leber's disease diagnosed and can it be cured?
Leber's optic neuropathy is a pathology that is difficult to diagnose. To make a diagnosis, a detailed medical history, study of heredity, and genetic prerequisites for the development of the disease are required. A complete neuro-ophthalmological diagnosis is carried out, which may include a fundus examination, visual field examination, optical coherence tomography, electroretinography, genetic consultation, mitochondrial DNA testing and a number of other diagnostic procedures.
If neurological signs are present, a differential diagnosis must be carried out, which allows one to determine whether a person suffers from Leber optic neuropathy or has another disease. Similar signs appear in retrobulbar neuritis against the background of multiple sclerosis, systemic lupus erythematosus and some other pathologies.
Unfortunately, to date, the mechanism of development of the disease has not been fully studied and there is no specific treatment for this pathology. If the diagnosis is confirmed, doctors prescribe symptomatic treatment with neurotrophins and metabolic therapy.
Today, scientists continue to study the mechanisms of development of hereditary neuropathy; we can only hope that in the future they will be able to find an effective way to preserve vision for people with this diagnosis.
Causes of Leber's hereditary optic neuropathy
The causes of Leber neuropathy, in which the optic nerve atrophies, are genetic. The disease, caused by a specific mutation in mitochondrial genes, is transmitted by women to their offspring. Men and women inherit pathology from their mother. Why is this happening? A huge amount of DNA is found in the cell nucleus and only a small part of it is in the mitochondria. Nuclear genes are inherited from both mother and father, but mitochondrial genes are inherited only from the mother. A man who inherits a mutation will not pass it on to his descendants.
In a significant proportion of people who are carriers of the mutated gene, the disease will not become apparent. More than 85% of women and 50% of men who are carriers of the LHON syndrome gene will not be affected by the disease. The reasons influencing the progression of the disease are not clear, but it is reliably known that the disease can be triggered by unfavorable environmental conditions, stress, infections, and the toxic effects of tobacco and alcohol.
Diagnosis of Leber optic neuropathy
Diagnosis of the disease is complicated by the similarity of its symptoms with ischemic neuropathy or with certain pathologies - for example, multiple sclerosis. It is also difficult to track the history, since not all carriers of the mutated gene develop Leber neuropathy. An extensive ophthalmological examination can only establish the presence of pathology, but to determine the cause, genetic diagnosis will be needed.
Features of diagnosing Leber hereditary optic neuropathy:
- general clinical examination;
- Mitochondrial DNA analysis;
- visual field examination;
- fundus examination;
- coherence tomography and electroretinography (necessary to exclude retinal pathologies).
Specialists are recommended to carry out a differential diagnosis of LHON syndrome by comparing symptoms and examination data with other diseases affecting the optic nerve. For example, with ischemic, toxic neuropathy. A complete ophthalmological examination shows that the optic disc is inflamed, and vascular telangiectasia (dilation of small capillaries) is also noticeable.
What are the symptoms of Leber optic neuropathy?
- As a rule, with this disease there is a sudden decrease in visual acuity in one and then in the other eye. Sometimes the pathological process is immediately bilateral. Also, in some cases, the loss of vision does not occur abruptly, but gradually.
- LHON is characterized by scotomas appearing in the visual field. Essentially, these are “blind” areas that limit the visibility area.
- During an ophthalmological examination, the doctor may detect redness and, at a later stage, blanching of the optic disc.
- Sometimes, along with ophthalmological symptoms, the patient complains of headaches, spasticity, dizziness, and tremor.
Leber's hereditary optic neuropathy - can the disease be cured?
While hereditary optic neuropathy is considered an incurable disease, scientists are constantly searching for new ways to treat such a pathology. Thanks to gene therapy methods, it is possible to significantly slow down the progression of diseases and improve the quality of life of patients.
The rapid progression of Leber's disease leads to rapid loss of vision in people who have seen normally all their lives and had no vision problems. A disappointing diagnosis, as well as information that the disease has not yet been treated, seriously affects the well-being of such patients who were not prepared for disability. Many of the existing methods of treating pathology have proven to be ineffective, including surgical intervention.
Fortunately, scientists involved in rare pathologies are working hard to find a cure. Experts place particular hope in gene therapy, and many research groups have already achieved good results. Sometimes an obstacle to continuing experiments is their ethical side, since further research involves the use of the developed technique on humans. Are there any successes at least using experimental models? Yes, geneticists have already managed to find a way to solve the problem.
Thus, a group of scientists from Miami, using experimental models, proved that mutated genes can be safely replaced with healthy ones, this will prevent deterioration in the nutrition of optic nerve cells. To correct a genetic defect in the mitochondria, it is necessary to introduce normal DNA - this will correct the disorder and restore visual function. Scientists report that this approach will also be effective against other diseases caused by mitochondrial mutations, as well as various disorders associated with the aging process.
Leber hereditary optic neuropathy (LHON)
In June 2011, Russell Wheeler's 24-year-old son Richard began experiencing vision problems. The examination revealed inflammation of the optic nerve, which, according to the doctor, was caused by a viral infection. Over the next few weeks, Richard's vision deteriorated rapidly, and after a series of tests, specialists suggested that it might be due to a rare condition called Leber's hereditary optic neuropathy (LHON), also known as Leber's disease. This is a congenital disease, transmitted through the mother's line, that causes rapid loss of central vision.
“None of us knew anything about this disease, and it was extremely difficult to get recommendations for its treatment,” says Russell, “This was also the first case for local doctors, so all their assumptions about the nature and course of the disease were based solely on information found on the Internet." The leading specialist the family contacted gave a disappointing prognosis. He confirmed that there was no chance of a cure, and Richard would have to get used to blindness.
“Of course, there are more terrible diseases than blindness, but loss of vision can lead to despair for any person. In addition, there is a possibility that Richard's brother, sister or mother could also suddenly develop symptoms of the disease,” says Russell.
Father and son both note that doctors are very sympathetic to their misfortune, but can do little to help beyond providing information, which is much more widely available on the Internet. Russell said: “The doctors placed us in the care of social services and charities such as the Royal National Institute of Blind People, which provide support with everyday problems. One of the few positive aspects in our situation is the exceptionally high consciousness and dedication of some representatives of these organizations, who provide assistance to us, despite their extremely limited financial capabilities.”
The Wheelers' main source of information and way of maintaining contact with people in the same situation is the support group on the social network Facebook and the website www. lhon.org, which publishes information about the newest available treatments and medications.
Russell, who is actively involved in the support group, believes that its efforts are not enough, especially for people new to the disease. This is what he says about this: “Not a single doctor, even one who considers himself a “specialist” in this disease, could provide us with the necessary information - we were completely left to our own devices.”
Until very recently, Leber's disease was considered incurable, and patients, as a rule, visited a specialist once every few years, since, in fact, no treatment was offered to them. As Russell says, “People simply got used to their new condition and went on with their lives.”
“Accordingly,” Russell suggests, “support groups are not particularly popular among patients with this disease because these groups lack a clearly defined purpose. The people who would benefit most from their activities have never heard of the disease or even suspect that it is the cause of their blindness.”
Therefore, Russell believes that the first priority is to raise awareness among professionals and patients about the disease. He hopes that the more people know about this disease, the greater the chance that money will be found to conduct research aimed at studying the causes of its occurrence and finding treatments: “Although Leber's disease is an orphan disease, it has a lot in common with other diseases, which means that the likelihood of obtaining positive results increases when conducting joint research in similar areas.”
Two orphan drugs were recently introduced for the treatment of Leber disease. One of them, intended for gene therapy, was presented by the French Institute of Vision and included in the orphan drug register in 2011. This news gives hope that treatments for this inherited disease may be found in the future.
This article was first published in the April 2012 issue of the EURORDIS newsletter Author: Irene Palko Photos: © Alethea Wheeler & www.lhon.org
Page created:
03/12/2012
Page last updated: 19/12/2012
