Retinitis pigmentosa is a genetically determined degeneration of the retina, in which the photoreceptors of the eyes perish bit by bit and thus in the late course of the disease usually complete blindness occurs. Frequently, this phenomenon is only one symptom of several and, together with the respective accompanying symptoms, forms an entire symptom complex, such as Usher or Alport syndrome.
What is retinitis pigmentosa?
Retinitis pigmentosa is a genetic disease of the retina that causes retinal degeneration and is also known as Patermann syndrome or retinopathia pigmentosa. The Dutchman Frans Donders documented the disease as early as 1855 and coined the term retinitis pigmentosa at that time. However, since the term retinitis actually denotes inflammation and the disease as such is not related to inflammatory processes, ophthalmology later renamed the phenomenon retinopathia pigmentosa. Nevertheless, Donder’s original naming is still in use today. About three million people worldwide suffer from retinitis pigmentosa, with adolescence and middle age being the peak phase of the disease. In the case of genetically determined retinal degeneration, general vision deteriorates bit by bit over several decades. About half of all patients develop a cataract at a later stage, which is accompanied by a general clouding of the lens. The disease also occurs in animals and is called progressive retinal atrophy by veterinary medicine.
Causes
Retinitis pigmentosa is a genetic defect. More than 40 different genes can cause the disease. Meanwhile, medicine assumes a monogenetic inheritance to pass on the genetic defect, which means that not several genes have to be defective, but the defect of only one of those identified so far can already trigger the disease. The disease is thought to be passed on in autosomal-dominant, autosomal-recessive and gonosomal inheritance. In addition to heredity, spontaneous mutation can also cause the pathological defect of one of the more than 40 identified genes. Under certain circumstances, toxic manifestations caused by substances such as chloroquine can be accompanied by the same symptoms as retinitis pigmentosa. In this case, however, physicians tend to refer to it as pseydoretinitis or phenocopy.
Symptoms, complaints, and signs
An early symptom of retinitis pigmentosa is night blindness. Due to the gradual destruction of photoreceptors, the eyes become less able to adapt to changing light conditions as the disease progresses, and they become increasingly sensitive to glare in response to light. Later, contrast vision and color vision are impaired. In the late course of the disease, most patients also suffer from an impairment of the visual field in the form of so-called tunnel vision. The central field of vision usually remains intact for a long time. However, complete blindness can occur in the late course of the disease. For almost a quarter of patients, retinitis pigmentosa is not a sole phenomenon, but is accompanied by many additional symptoms and thus takes the form of an entire syndrome, for example Usher syndrome. In this context, physicians also speak of associated retinopathy pigmentosa, which can be accompanied by hearing disorders, paralysis or cardiac arrhythmias or muscle weakness. In addition to Usher syndrome, Alport and Refsum syndromes are among the best-known complexes associated with associated retinitis pigmentosa.
Diagnosis and disease course
The diagnosis of retinopathia pigmentosa is made by electroretinogram. This electroretinogram allows the diagnosis to be made in early childhood. Ultimately, the earlier the diagnosis, the more favorable the prospects of being able to cope with the disease in the late course. The prognosis depends strongly on which of more than 40 causative genes is affected by the defect, although the disease is currently considered incurable except for the special form of refsum syndrome. In order to assess the exact location of the gene effect and to be able to give a prognosis, the doctor first analyzes all additional symptoms and, in the course of this, obtains an impression of hearing disorders and blood values, for example. Only when the exact gene defect has been determined can a DNA analysis be performed.
Complications
Retinitis pigmentosa is a hereditary disease of the retina that invariably leads to blindness via night blindness, reduction in visual field and visual acuity. There is currently no therapy that promises a cure. Possibly the course can be slowed down by vitamin A. Additional complications occur in those forms of retinitis pigmentosa in which other organs of the body are also affected by disease symptoms. This is the case in about 25 percent of all those affected. Depending on the syndrome, additional hearing problems, paralysis, muscle weakness, cardiac arrhythmias or mental developmental disorders may occur. Within the eyes, sometimes other changes appear, such as calcifications in the optic nerve, corneal curvature, lenticular opacities, myopia or vascular diseases. In Usher syndrome, for example, there is also severe hearing impairment in addition to retinitis, which is primarily due to damage to the hair cells. Retinitis pigmentosa also occurs in Laurence-Moon-Biedl-Bardet syndrome. Here, in addition to retinitis, diabetes mellitus, hypertension, obesity, muscle weakness, hearing loss, mental retardation, and motor function disorders occur. Cardiovascular problems may occur as a result of diabetes and hypertension. In other associated forms of retinitis pigmentosa, cardiac arrhythmias may also occur, sometimes leading to life-threatening complications. Further complications also result from gait disturbances, which can often cause falls. Sometimes neurodegenerative disorders such as dementia development also occur with retinitis pigmentosa.
When should you see a doctor?
Retinitis pigmentosa always needs to be evaluated and treated by a doctor. There can be no self-healing with this disease and, in the worst case, the affected person may go completely blind. The earlier the disease is detected and treated, the higher the probability of a complete cure. A doctor should be consulted if the patient suffers from night blindness. In this case, the affected person can hardly see and recognize anything at night. The vision of different colors can also be affected by retinitis pigmentosa and should be examined by a doctor. However, those affected also suffer from hearing problems or heart complaints as a result of the disease. If these symptoms occur, it is imperative to see a doctor. First and foremost, retinitis pigmentosa is treated by an ophthalmologist. The further complaints can then also be treated by a cardiologist or by an ENT specialist. Whether a complete cure can be achieved cannot generally be predicted.
Treatment and therapy
The progression of retinopathia pigmentosa cannot be stopped for most forms of the disease to date. However, vitamin A supplementation has been reported to slow progression in combination with hyperbaric oxygen therapies, according to clinical trials. Management of the disease is currently the focus of therapy. For example, psychological support and early introduction to orientation techniques for the blind are intended to better prepare patients for the possible imminent loss of sight. Refsum syndrome is an exception, because this is actually a metabolic defect whose progression can be halted by a special diet low in phytanic acid. For all other forms, experiments are currently underway with stem cell therapies and replacement of the defective genes directly in the retina. To repair pre-existing retinal damage, the medical community is also currently looking at developing retinal implants to compensate for photoreceptor loss of function. A subretinal implant of 1500 diodes may thus make vision possible again in the future.
Prevention
Retinitis pigmentosa cannot be prevented because the disease is a genetic defect.
Aftercare
In most cases, those affected by retinitis pigmentosa have only a few and also only limited options or measures of aftercare available. First and foremost, a physician should be consulted at a very early stage so that complications or other complaints do not arise in the further course of the disease.This is crucial for the further course of the disease, so a doctor should be contacted at the first signs and symptoms of the disease. The treatment of retinitis pigmentosa is usually done by taking various medications, mainly antibiotics are used. Regular intake with a correct dosage should always be observed, and antibiotics should also not be taken together with alcohol. In many cases, the support and help of one’s own family is also necessary so that depression or psychological upsets do not occur. In the case of children, it is above all the parents who must ensure that the medication is taken correctly and regularly. A general course cannot be predicted, although in some cases there may be a reduced life expectancy of the affected person.
Here’s what you can do yourself
Retinitis pigmentosa is a hereditary retinal disease and currently has no cure. As retinal cells die, the affected person’s field of vision narrows. Spatial vision is lost. Walking with a blind man’s cane replaces his spatial orientation. On the other hand, RP sufferers with tunnel vision are often still able to read with a magnifying glass. The cones, which are located in the center of the retina, are responsible for this. They are functional longer than the rods, which enable night and twilight vision. If these have died off, the affected person is dependent on the help of an attendant. It is important that outsiders be made aware of the progressive and worsening blindness. Wearing the badge for the blind provides clarity. Aids such as Braille or voice-controlled computers make everyday life easier for the person affected. The high sensitivity to glare is attenuated with tinted glasses. If contrasts become blurred and contours in the home can no longer be perceived, the person affected is helped by markings that he or she can feel with his or her hands. Colored markings, on the other hand, are not suitable because color vision is also impaired. RP sufferers are entitled to a severely disabled person’s card. If the patient has a well-developed visual center, he can be implanted with a chip that helps him recognize the contours of objects.
