Macular degeneration (MD) and retinitis pigmentosa (RP) are eye diseases that affect the retina, which is the light-sensitive layer of tissue at the back of the eye. Alongside a functioning center called the macula, the retina contains photoreceptors, the optic nerve, and blood vessels.
When light hits the retina, the photoreceptors convert the light into electrical signals. The optic nerve sends these signals to the brain, enabling a person to see.
A damaged retina due to MD or RP causes varying degrees of vision loss. Whereas MD occurs due to aging, RP is an inherited disease that typically develops in childhood or young adulthood.
This article provides an overview of MD and RP, including the links and differences between the two diseases. It also discusses the symptoms and causes of each disease and provides a list of other eye conditions that may cause symptoms similar to those of MD and RP.
Below, we look at MD and RP in more detail.
Macular degeneration
MD is an eye disease that involves damage to the macula, which is the light-sensitive tissue that forms part of the retina. The condition causes changes to a person’s central vision, which is what a person sees while looking straight ahead. Central vision is helpful for the following:
- recognizing faces
- reading and writing
- driving
- seeing fine details
- doing close up work, such as threading a needle
MD does not affect a person’s peripheral vision, which is what a person sees on the periphery of their central vision, outside the point of fixation.
According to the National Eye Institute (NEI), MD affects
Types
There are two types of MD: dry and wet. Dry MD occurs when the macula becomes thinner with age. Wet MD occurs when abnormal blood vessels grow underneath the macula and leak blood and fluid that results in scarring and vision loss.
According to the American Academy of Ophthalmology (AAO), about 80% of people who have MD have the dry form. However, it is possible for people to develop both dry and wet MD.
Retinitis pigmentosa
RP is an umbrella term for rare eye disorders that cause the breakdown and loss of cells in the retina.
The National Organization for Rare Disorders states that RP is a rare genetic disorder that affects somewhere between 82,500 and 110,000 people in the U.S. The symptoms typically start between the ages of 10 and 40 years and gradually worsen over time.
According to the
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Researchers have also found that mutations in the peripherin-2 (PRPH2) gene may be associated with the development of both MD and RP.
Healthy peripherin-2 protein is necessary for the proper functioning of photoreceptors called rods and cones, which are responsible for sight. Rods work at low levels of light, while cones allow a person to see color. Rod damage causes RP, while cone degeneration causes MD.
MD and RP both cause loss of vision. The table below shows the differences between the two disorders:
| Macular degeneration | Retinitis pigmentosa |
| results in the loss of central vision | results in the loss of peripheral vision |
| usually starts after the age of 50 years | usually starts in |
| has two types | has several types |
| primarily affects the eye’s cones | primarily affects the eye’s rods |
| there are | the |
| rarely causes complete blindness | may cause complete blindness |
| is common | is rare |
MD and RP both affect the vision, but they produce different symptoms.
Macular degeneration symptoms
MD is a progressive disease, meaning that the symptoms usually worsen over time.
The symptoms of MD depend on the stage of the disease. There are
- Early: Symptoms are not usually present at this stage.
- Intermediate: Symptoms may include:
- mild blurriness of central vision
- difficulty seeing in low lighting
- slow recovery of visual function after exposure to bright light
- Late: Symptoms include:
- blind spots
- colors appearing darker or washed-out
- seeing straight lines as wavy or distorted
Retinitis pigmentosa symptoms
The symptoms of RP vary from person to person, but they may include:
- loss of color vision
- sensitivity to bright light
- difficulty seeing in dimly lit areas
- difficulty adjusting to changes in lighting
- seeing white flashes or colored blobs of light
- eye floaters or black specks in the field of vision
MD and RP have different causes and risk factors.
Macular degeneration causes and risk factors
MD develops due to a combination of genetic and environmental factors.
The risk of MD
- having a family history of MD
- being white
- smoking
- having excess body weight
- having high blood pressure
- eating a diet high in saturated fat
- having high cholesterol levels
- living with heart disease
A person can reduce their risk of developing MD by quitting smoking or never starting.
Retinitis pigmentosa causes and risk factors
RP occurs due to a genetic disorder. The National Institutes of Health (NIH) note that genetic changes to any one of more than 50 genes may cause RP.
In some cases, RP develops due to another genetic condition, such as
Possible risks and complications of MD and RP include:
- worsening vision changes
- cataracts
- macular edema
- changes in quality of life that can lead to depression and anxiety
- higher risk of falls, accidents, or injury due to progressive vision loss
Other eye conditions that may cause symptoms similar to those of MD and RP include:
- Glaucoma: Glaucoma refers to a group of eye conditions that cause damage to the optic nerve.
- Cataracts: These are cloudy areas in the lens of the eye.
- Detached retina: The retina can sometimes separate from the blood vessels that supply it with blood and oxygen.
- Diabetic retinopathy: This term refers to damage to the blood vessels of the retina due to complications of diabetes.
- Eye melanoma: This cancer affects pigment-producing cells called melanocytes within the eye.
- Ocular cancer: Ocular cancer describes any cancer of the eye.
A person with MD or RP will develop varying levels of vision loss.
Treatments do not cure MD and RP, but they may help slow the progression of these diseases. In addition, therapies such as vision rehabilitation can help a person deal with vision loss from MD and RP.
More treatment options are available for MD than for RP. Often, people with RP can seek help from eye doctors specializing in low vision.
The American Foundation for the Blind provides resources to help people manage new vision loss.
Macular degeneration and retinitis pigmentosa are eye disorders that can cause vision loss. Whereas MD is an age-related condition, RP is an inherited condition that typically develops in childhood or young adulthood.
Several other eye conditions can cause symptoms similar to those of MD and RP. A person who experiences any concerning eye symptoms should consult an eye doctor for a diagnosis.
Although there is no cure for either MD or RP, early detection and treatment can help slow disease progression and prevent possible complications. In addition, therapies such as vision rehabilitation can help a person deal with vision loss. Anyone needing further advice and guidance should talk with an eye doctor.