Retinitis pigmentosa (RP) is a broad category of hereditary visual diseases that affect the retina, the light-sensitive membrane that lines the interior of the eyes. Peripheral (or side) vision gradually deteriorates until it is gone in the majority of instances. Typically, central vision is retained until late in these situations.
Certain types of Retinitis pigmentosa have been linked to deafness, obesity, renal illness, and various other general health issues, including central nervous system and metabolic diseases and chromosomal abnormalities on occasion.
Signs & Symptoms
Retinitis Pigmentosa often begins as a visual impairment at night or in low light. Such is difficulties seeing in poorly lit surroundings or at twilight, or trouble adjusting to or regaining function in dim light following prolonged exposure to bright light. This is typically followed by the affected individual becoming increasingly conscious of a loss of peripheral vision. Although symptoms are most frequently detected between the ages of 10 and 40, there are early and late-onset types of RP.
Symptoms often develop gradually over time. The emergence of these symptoms suddenly should indicate a distinct etiology, such as an autoimmune disease. Seniors who get these symptoms suddenly are at an increased chance of acquiring them as a result of malignancy. This is referred to as paraneoplastic retinopathy, and it frequently co-occurs with optic nerve involvement.
The rate and amount of vision loss development in RP might vary. How peripheral vision is lost in RP has been particularly clearly described by several writers. According to numerous researches, the most variable factor is the age at which symptoms begin. Not just across families and subtypes of RP, but even within families, this might differ. After then, however, the pace and mode of growth often follow a very predictable and conventional exponential pattern.
This pattern indicates that individuals suffer a reduced rate of illness development during the first decade of symptomatic disease, which then increases during the succeeding two decades before slowing again for the duration of life.
When additional family members are affected, the rates of development are frequently comparable within the family, although there is considerable heterogeneity in this component of Retinitis Pigmentosa. Certain people with RP or associated diseases have complicated symptoms involving other organs, dubbed “syndromes.” The most frequent connections of RP with systemic health issues that contribute to the development of these more complicated disorders include hearing loss and obesity.
Causes
Retinitis pigmentosa is a set of progressive autosomal recessive, autosomal dominant, or X-linked recessive diseases. Maternally inherited variations of RP can also exist and are transmitted via mitochondrial DNA.
Approximately half of all instances of RP are isolated and have no family history of the condition. RP may manifest alone or in combination with one of several other uncommon diseases. Over 60 systemic diseases have comparable retinal involvement to RP.
Autosomal dominant diseases develop when just one copy of a gene contains a variation (mutation) sufficient and essential for the disease to manifest. In dominant diseases, the faulty gene may be inherited from either parent or spontaneously arise in the afflicted individual. The probability of passing the defective gene on to kids from an afflicted parent is 50% for each pregnancy, regardless of the parent’s or child’s sex.
However, in some types of dominant illnesses, including some types of dominant RP, patients who inherit the mutant gene either do not get the disease or have a very weak version of it due to a condition known as incomplete penetrance. The RP11 (PRPF31) gene, which causes autosomal dominant RP, is particularly prone to this, posing a substantial diagnostic problem. Children who did not inherit the gene variation causing the autosomal dominant condition in question cannot get the disease, even if they are born to afflicted patients.
When an individual inherits mutations in the same gene from both parents, autosomal recessive diseases arise. When individuals inherit one normal gene and one illness gene, they become carriers of the disease but often do not exhibit symptoms. Each pregnancy increases the probability of two carrier parents transmitting the changed gene and producing an afflicted kid by 25%.
Each pregnancy increases the likelihood of producing a kid who is a carrier, just like the parents. Additionally, the likelihood of producing a child who inherits normal genes for that characteristic from both parents is 25%. Males and females are equally at risk.
All offspring born to an autosomal recessive parent will inherit one copy of the changed gene. As a result, they will be healthy carriers, just as the afflicted patient’s parents were. A kid born to a patient with an autosomal recessive illness can be impacted only if the affected parent mates with someone who also carries mutations in the same gene that causes the patient’s sickness. If this occurs, the likelihood of having an afflicted kid increases to 50%.
If an afflicted person mates with another affected person who also has the illness caused by a mutation in the same gene, their chance of producing a kid with the same genetic condition is 100%, as long as the gene responsible for the disease is identical in both parents.
Because most people carry a few abnormalities in their genes, parents who are close blood relatives (consanguineous) have a greater chance of both carrying the same abnormality in any given gene than unrelated parents do, increasing the risk of having children with an autosomal recessive genetic disorder.
Typically, these offspring will have identical alterations in both copies of their DNA (homozygous). However, autosomal recessive diseases generally occur due to an accidental mating between two healthy carriers who each have a unique mutation in the same gene (compound heterozygous).
Diagnosis
Electroretinography (ERG) measures the electrical responses of various cell types in the retina, including the photoreceptors, inner retinal cells, and the ganglion cells, demonstrating a gradual loss of photoreceptor function. Visual field testing and retinal imaging, primarily optical coherence tomography (OCT) and fundus auto-fluorescence (FAF), will reveal precise microanatomical characteristics not visible to the naked eye. To confirm the diagnosis, molecular genetic testing for mutations in a large number of the genes linked with RP is available.
Treatments
Dietary Supplements: Over the previous two decades, the treatment regimen for people with RP has developed. A six-year study conducted at Harvard Medical School with funding from the National Eye Institute and the Foundation Fighting Blindness found that patients who received 15,000 IU (international units) of vitamin A palmitate daily had a slower decline in retinal function than those who received only trace amounts.
Artificial Silicon Retina (ASR) microchip for the treatment of vision loss from retinitis pigmentosa
Dr. Peyman was one of the first to implant a silicone prosthetic retina in retinitis pigmentosa patients.
The ASR microchip is a silicon-based device with a 2-mm diameter that comprises about 5000 micro photodiodes with microelectrode tips and is driven by incident light. Six individuals with retinitis pigmentosa had the ASR microchip implanted in their right eyes, while their left eyes acted as controls.
Results – All ASRs functioned electrically over a 6- to 18-month follow-up period. There were no indications of implant rejection, infection, inflammation, erosion, neovascularization, retinal detachment, or migration observed in any patient. All patients saw improvements in visual function, including surprising improvements in retinal regions far from the implant.
Make an appointment now with Arizona Retinal Specialists
If you have increasing problems with your vision or have not had an eye exam in some time, please contact AZRS soon and make an appointment. At Arizona Retinal Specialists, you’ll discover a committed team of specialists and a range of therapies aimed at enhancing your vision’s health. We are devoted to providing the greatest quality care possible while employing cutting-edge diagnostic and medical treatment technologies. Call 623 – 474 – 3937 (EYES) now!
