Retinitis pigmentosa: Description
Retinitis pigmentosa (retinopathia pigmentosa) is a large group of genetic eye diseases, all of which lead to the gradual death of the visual cells in the retina, i.e. the rod and cone cells. Visual disturbances up to blindness are the consequences. In most cases, both eyes become diseased; in rare cases, retinopathia pigmentosa affects only one eye.
In medicine, the suffix “-itis” usually stands for inflammation. Retinitis, however, is not an inflammation of the retina, but another form of retinal disease. More correct is therefore retinopathia (“-pathia” = disease). Nevertheless, “retinitis” has become accepted for this clinical picture.
Forms of retinitis pigmentosa
- autosomal-dominant retinitis pigmentosa (frequency: 20 to 30 percent)
- autosomal recessive retinitis pigmentosa (incidence: 15 to 20 percent)
- X-recessive retinitis pigmentosa (frequency: 10 to 15 percent)
Read more about the three forms of inheritance below in the section “Causes and risk factors”.
- congenital hepatic amaurosis (frequency: 5 percent)
- digenic retinitis pigmentosa (“digenic” means there is a mutation in two genes; frequency: very rare)
- Usher syndrome (with loss of hearing and vision; frequency: 10 percent)
- Bardet-Biedl syndrome (with retinal degeneration, limb abnormalities, obesity; frequency: 5 percent)
Concomitant diseases
Slow blindness also puts a strain on the psyche of those affected. Thus, depression is not uncommon in retinitis pigmentosa patients. They should be recognized and treated as early as possible in order to enable those affected to enjoy a better quality of life.
Retinitis pigmentosa: symptoms
All forms of retinitis pigmentosa have in common that the retinal cells responsible for vision (rod and cone cells) gradually die off.
- Cones cells are predominantly located in the center of the retina and enable humans to see colors during the day as well as to see in focus.
Symptoms due to the death of rods and cones
The symptoms of retinitis pigmentosa can be attributed to the gradual death of the two cell types:
- progressive night blindness (usually the first sign)
- increasing visual field loss, e.g. in the form of increasing tunnel vision (early sign)
- increased sensitivity to glare
- disturbed contrast vision
- prolonged adaptation time of the eyes, for example, when changing rapidly from a bright to a dark room
- gradual loss of visual acuity
- complete blindness
Retinitis pigmentosa: night blindness
Retinitis pigmentosa: visual field loss
The visual field restriction manifests itself differently – depending on the form of retinitis pigmentosa. Often, the visual field narrows from the outside inward to tunnel vision. In other cases, deficits around the center or patchy over the entire visual field are possible. More rarely, the affected person loses his visual field from the inside to the outside.
Retinitis pigmentosa: color vision and light sensitivity
Other symptoms
In addition to the symptoms mentioned above, retinitis pigmentosa also shows typical signs at the back of the eye:
- narrowing of the blood vessels
- waxy yellow papillae
- changes of the macula lutea (“yellow spot”)
- pigment deposits (“bony corpuscles”)
In addition, changes are known to affect the vitreous body of the eye:
- Lens opacity
- Drusen papilla (calcium deposits in the optic nerve head)
- Nearsightedness (myopia)
- Keratoconus (deformation of the cornea)
However, the last two symptoms (keratoconus and inflammatory vasculopathy) occur rather rarely in retinitis pigmentosa.
Retinitis pigmentosa: Causes and risk factors
The cause of retinitis pigmentosa is exclusively hereditary. Four aspects play a role, which are causative for the many subtypes and thus the course of the disease:
- Several thousand different mutations at these genes are known.
- Different mutations on one and the same gene can cause different subtypes.
- One and the same mutation at one gene can lead to different clinical symptoms.
Death of the cone cells is unexplained
Retinitis pigmentosa: Three forms of inheritance
A mutation can be inherited from one generation to the next (because it is already present in the father and/or mother) or it “arises anew” when the paternal and maternal genetic material mix after fertilization of the egg and sperm cell. A damaged gene can, but does not necessarily, lead to the disease. This depends on whether the gene is dominant or recessive and on which chromosome it is located.
The transmission of genes on the autosomes is called autosomal inheritance, the transmission of genes of the sex chromosomes is called gonosomal inheritance. There are now three possible forms of inheritance in retinitis pigmentosa:
- autosomal dominant inheritance: The mutated gene is dominant, so that one copy is sufficient for the onset of the disease – it prevails against the second, healthy gene copy.
Retinitis pigmentosa: Genetic counseling
Retinitis pigmentosa: examinations and diagnosis
If you may have retinitis pigmentosa, the ophthalmologist will first talk with you in detail about your medical history (medical history). He will ask, for example:
- Do you have difficulty seeing in the dark?
- If so, how long have you had difficulty seeing in the dark?
- Is there anyone in your family who is slowly going blind?
- Does an object become sharper if you do not look at it directly, but just past it?
- Is your field of vision restricted, for example by blotchy areas or by a narrowing from the outside?
In addition, the doctor will ask you about possible other causes of vision problems. For example, drug intoxication, tumor disease, and other retinal diseases such as congenital night blindness cause symptoms similar to retinitis pigmentosa.
Functional diagnostics
- Visual acuity (with an eye test)
- Color vision (usually with the Lanthony panel D-15 desaturated test)
- Visual field (usually with a so-called perimeter such as the Goldmann perimeter)
- Adaptability from light to dark (with a dark adaptometer)
General eye exams help the doctor check your eyes for typical changes such as increased retinal pigmentation, blood vessel narrowing, or lens opacity.
If the disease is very advanced, pupillography can be used to test the function of the pupil under different light conditions. However, this examination is only offered by special centers, usually in the context of scientific studies.
Genetic diagnostics
Retinitis pigmentosa: Treatment
At the moment, retinitis pigmentosa cannot be treated, with a few exceptions (such as atrophia gyrata, Bassen-Kornzweig syndrome). Therefore, treatment is limited to alleviation of symptoms with:
- eyeglasses, contact lenses or magnifying vision aids
- UV-protective lenses
- Edge filter lenses (lenses with UV protection and filters for specific wavelengths of light)
- specialized computer software
- Cane for the blind
- Orientation and mobility training
Retinitis pigmentosa: therapy in prospect?
For more than two decades, scientists have been vigorously searching for possible therapies for retinitis pigmentosa. Research is being conducted into various ways of halting the disease or preventing it completely. Attempts are being made to correct the genetic defect, to prevent the death of the photoreceptors or to rebuild dead photoreceptors. Promising methods include:
- Stem cell therapy: stem cells that become retinal cells and replace dead cells.
- Medications such as unoprostone isopropyl eye drops, QLT091001, valproic acid.
- Cell protection: growth factors (such as CNTF) or factors that prevent cell death (such as DHA), or RdCVF to prevent cone cell death
- Optogenetics: Using genetic engineering, light-sensitive channels or pumps are integrated into the photoreceptor cells to restore their function.
Many of these technologies are currently being researched in studies – in the test tube, in animals and some already in humans. Affected people therefore have the opportunity to participate in one of the current studies. However, such studies do not exist for all subtypes of retinitis pigmentosa.
Retinitis pigmentosa: disease course and prognosis
Since there is still no cure, countless subtypes of retinitis pigmentosa exist with different courses and affected people, but also relatives, often feel left alone, detailed discussions with the ophthalmologist are highly recommended. An important contact point is also Pro Retina, a self-help association for people with retinal degeneration such as retinitis pigmentosa.
