Retinitis pigmentosa (RP) is a group of rare genetic diseases that affect the light-sensitive part of the eye, called the retina. “Atypical RP” refers to RP that lacks the characteristic features of the condition.

Over time, RP causes the cells of the retina to break down, resulting in vision loss. The treatment for RP depends on the type a person has.

Some treatments aim to slow vision loss, while others help people make the most of their remaining vision.

This article examines atypical RP.

An eye pupil close up with a beam of light shining over it, representing atypical retinitis pigmentosa. -1Share on Pinterest
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According to the National Eye Institute (NEI), retinitis pigmentosa (RP) is a group of rare eye diseases that affect the retina, causing vision changes.

The retina consists of layers of cells at the back of the eye that capture photons of light, convert them into electrical and chemical signals, and transmit these signals to the brain.

This process allows the brain to perceive visual stimuli.

In RP, the cells of the retina gradually break down, resulting in vision loss. RP can sometimes include other features as well. For example, in a condition known as Usher’s syndrome, RP occurs alongside hearing loss.

Atypical forms of RP lack the usual characteristic features of the condition.

Learn more about RP.

A 2018 case report outlines some of the typical features of RP:

  • needle-like or “spicule-like” shapes in the retinal pigment epithelium, which is a layer of cells that help nourish the retina and allow its photoreceptors to detect light
  • waxy optic disc pallor, which is a sign of damage to the optic nerve
  • narrowing of the blood vessels in the back of the eye

According to the report, atypical RP is a subtype of RP in which the above features are absent.

People with RP or atypical RP may experience the following types of vision loss:

  • Loss of night vision: People with RP may have normal vision during the day but may develop night blindness. This means the eyes take longer to adjust to darkness. According to the NEI, night blindness is the most common early symptom of RP. A person experiencing night blindness may:
    • have difficulty driving at dusk and at night
    • have difficulty seeing in dimly lit rooms
    • stumble over objects in the dark
  • Gradual loss of peripheral vision: People with RP may gradually lose their side or peripheral vision, meaning they have difficulty seeing objects that are outside the center of their visual field. Eventually, this may progress to “tunnel vision.” Bumping into objects is one possible symptom of tunnel vision.
  • Loss of central vision: Some people with RP develop central vision loss, which affects their ability to see in detail. Central vision loss can cause difficulty with:
    • reading
    • driving
    • detailed tasks such as threading a needle
  • Issues with color vision: Some people with RP may have difficulty seeing different colors.
  • Photosensitivity: According to the NEI, sensitivity to bright light is another possible symptom of RP.

RP is a rare genetic condition, which means parents can pass it to their children.

The condition causes changes to genes that control cells in the retina.

Some people develop RP due to another genetic condition, such as Usher syndrome.

Less common causes of RP include:

  • certain medications
  • infections
  • eye injury

Atypical RP may have the same causes and risk factors.

People with atypical RP may have difficulty receiving a correct diagnosis since they lack the characteristic features of the condition.

According to the American Academy of Ophthalmology, doctors may use the following procedures to diagnose typical or atypical RP:

  • Genetic testing: This procedure involves checking blood or tissue samples for genes associated with RP. It can help doctors predict the course or severity of the disease and make decisions about treatment.
  • Electroretinography: This procedure measures how effectively the retina’s cells respond to light.
  • Visual field testing: This procedure measures peripheral vision and can help detect the size, shape, and location of any blind spots.
  • Optical coherence tomography: This imaging test takes highly detailed pictures of the retina. It can help doctors diagnose RP and determine how it is affecting a person’s vision.

For example, in a 2018 case report, three people with atypical RP had previously received one of the following incorrect diagnoses:

  • age-related macular degeneration
  • intermediate uveitis
  • cystoid macular edema

There is no single treatment for RP, since more than 100 genes can cause the condition.

However, scientists continue to study the genetic causes of RP to develop appropriate treatments.

To date, potential treatment options for RP and its possible complications include:

  • Genetic therapies: These therapies aim to treat certain forms of RP by identifying the defective gene and correcting its DNA. One form of RP results from a defect in the RPE65 gene. Doctors can now treat this form of RP by injecting a medication called voretigene neparvovec-rzyl under the retina during eye surgery.
  • Vitamin A supplements: Vitamin A may slow the progression of some forms of RP, though high intake of this vitamin may worsen other eye conditions and can have other negative health effects. A person can talk with their ophthalmologist about the risks and benefits of vitamin A.
  • Fish oil and lutein supplements: These supplements may help slow down vision loss.
  • Medications for macular edema: Macular edema is a condition in which blood vessels leak into a part of the retina called the macula, causing it to swell. Ophthalmologists may recommend eye drops or oral medications to reduce macular edema in people who develop this condition as a result of RP.
  • Cataract surgery: A cataract is a cloudy patch on the lens of the eye, which may cause blurred vision and eventual vision loss. Ophthalmologists may recommend cataract removal surgery to improve vision in people who develop cataracts as a result of RP.
  • Low vision rehabilitation (LVR): People with vision problems may need LVR services to help them make the most of their remaining vision, complete day-to-day tasks, and improve their quality of life. An LVR team can also provide tools to improve vision, such as:
    • glasses
    • magnifiers
    • electronic devices

People with RP typically experience a gradual decline in their vision. According to the NEI, most people with the condition will eventually lose most of their vision.

However, total vision loss due to RP is uncommon.

The outlook for RP depends on the type a person has and their age at the time of disease onset. Two key types of RP and their prognoses are as follows:

  • Autosomal dominant RP: This is the least severe form of RP and tends to have a more gradual onset of symptoms in later adulthood.
  • X-linked recessive RP: This is the most severe form of RP.

People with RP can take steps to make the most of their vision. One way to do this is to have regular eye examinations so that doctors can detect and treat possible complications of RP early.

Possible complications of RP include:

  • refractive errors
  • cataracts
  • cystoid macular edema, which is the formation of small pockets of fluid in the macula

Retinitis pigmentosa (RP) is a group of rare genetic diseases that affect the retina, causing vision loss.

Atypical RP lacks the characteristic features of the condition. As a result, people with atypical RP may have difficulty getting a correct diagnosis.

Possible symptoms of RP include night blindness, tunnel vision, and loss of central vision.

Scientists continue to investigate the various genetic causes of RP to develop appropriate treatments. Genetic therapies are already available for certain forms of RP, and many people with RP can benefit from low vision rehabilitation.

Most people with RP will eventually lose most of their vision, but total vision loss is uncommon. A person can talk with an ophthalmologist to learn more about their type of RP and its outlook.