In medical contexts, RP most commonly stands for retinitis pigmentosa, a group of genetic eye disorders that cause progressive vision loss by destroying the light-sensing cells in the retina. It affects roughly 1 in 4,000 people worldwide, and many who have it are legally blind by age 40. The abbreviation can also refer to a few other conditions, including relapsing polychondritis and Raynaud’s phenomenon, though retinitis pigmentosa is by far the most frequent use.
Retinitis Pigmentosa: The Primary Meaning
Retinitis pigmentosa isn’t a single disease. It’s a family of inherited conditions that all share the same basic problem: the photoreceptor cells in your retina, the thin layer of tissue at the back of your eye, gradually break down and die. These cells are what convert light into electrical signals your brain reads as vision.
The damage starts with rod photoreceptors, the cells responsible for seeing in dim light and detecting movement at the edges of your visual field. Over time, the loss of rods also harms the surrounding tissue and eventually damages cone photoreceptors, which handle color vision and sharp central sight. This is why RP follows a predictable pattern: night blindness comes first, peripheral vision narrows next, and central vision deteriorates last.
How Symptoms Progress
The earliest sign is usually difficulty seeing in low light, often noticeable in childhood. You might struggle to navigate a dimly lit room or take longer than others to adjust when the lights go down. Around the same time or shortly after, peripheral vision begins to shrink. Objects at the edges of your sight become harder to detect, which can make activities like driving or walking through crowded spaces feel increasingly difficult.
As the disease advances, the visual field continues to narrow. What remains is sometimes described as tunnel vision, as if you’re looking through a paper towel roll. Many people with RP reach a central visual field of less than 20 degrees in diameter, which meets the threshold for legal blindness. Eventually, most people lose both peripheral and central vision, though the rate varies widely. Some retain useful sight into middle age, while others experience faster decline.
Genetics and Inheritance
RP is caused by mutations in any of dozens of different genes, all of which play a role in how photoreceptor cells function or maintain themselves. The condition follows three main inheritance patterns. About 20 to 25 percent of non-syndromic cases are autosomal dominant, meaning one copy of the mutated gene from one parent is enough to cause the disease. Another 15 to 20 percent are autosomal recessive, requiring a mutated copy from both parents. Around 10 to 15 percent are X-linked, which primarily affects males. A significant portion, roughly 30 percent, are classified as sporadic, meaning there’s no clear family history.
One gene that has received particular attention is RPE65, which produces a protein critical for regenerating the visual pigment that both rods and cones need to detect light. Mutations in RPE65 account for about 2 percent of recessive RP cases and a much larger share of a related condition called Leber congenital amaurosis, an even earlier-onset form of retinal degeneration.
How RP Is Diagnosed
An eye exam can raise suspicion, but the key diagnostic tool is an electroretinogram, or ERG. This test measures the electrical activity of your retina in response to flashes of light. In someone with RP, the electrical signals generated by rod cells are weaker and slower than normal in the early stages. As the disease progresses, the combined rod and cone responses also diminish. In severe or late-stage cases, the retina may produce little to no measurable response at all.
Genetic testing is increasingly used alongside the ERG. Identifying the specific mutation matters because it determines the inheritance pattern, helps predict how the disease may progress, and, in at least one case, opens the door to a targeted treatment.
Treatment Options
There is currently one FDA-approved gene therapy for a form of RP. It targets patients with confirmed mutations in both copies of the RPE65 gene. The treatment delivers a working copy of the gene directly into the retinal cells, restoring their ability to produce the protein needed for the visual cycle. It doesn’t cure the disease or fully restore vision, but clinical trials showed meaningful improvements in the ability to navigate in low light.
For the majority of people with RP whose mutations aren’t in RPE65, management focuses on slowing progression and adapting to vision changes. Low-vision aids, orientation and mobility training, and assistive technology all play practical roles. Research into additional gene therapies, retinal implants, and stem cell approaches is active but has not yet produced other approved treatments.
Other Medical Meanings of RP
While retinitis pigmentosa is the dominant meaning, two other conditions sometimes appear as “RP” in medical records or discussions.
Relapsing polychondritis is a rare autoimmune disorder in which the body attacks its own cartilage. The most recognizable symptom is sudden redness, swelling, and pain in the ear (specifically the firm cartilage, not the soft lobe). Nasal cartilage is the next most common target, and repeated flares can cause structural damage: floppy ears, a collapsed nasal bridge, or a sunken chest wall. It can also affect the airways, joints, and eyes.
Raynaud’s phenomenon involves episodes where blood flow to the fingers, toes, or other extremities drops sharply in response to cold or stress. During an attack, the skin turns white as blood flow stops, then blue as oxygen in the tissue is used up, then red as circulation returns. The affected areas feel cold and numb during the episode and may throb or tingle as they warm. Raynaud’s is far more common than the other two conditions, but in medical shorthand it is more often abbreviated as “RP” in rheumatology contexts than in general practice.
If you encounter “RP” in a medical document and the context isn’t clear, the surrounding specialty usually tells you which condition is meant. Ophthalmology records almost always mean retinitis pigmentosa. Rheumatology notes could point to either relapsing polychondritis or Raynaud’s phenomenon.