Choroidal Neovascularization
Abnormal blood vessels growing under the retina
Quick Facts
- Type: Eye / retinal condition
- Main problem: Leaky abnormal vessels under the retina
- Main effect: Distorted or lost central vision
- Seek urgent care: Sudden vision changes or distortion
Overview
Choroidal neovascularization (CNV) is the growth of new, abnormal blood vessels from the choroid, a layer of blood vessels beneath the retina, up toward or under the retina itself. These new vessels are fragile and leak fluid or blood. When this happens under the macula, the central part of the retina, it disturbs the delicate tissue responsible for sharp, detailed vision.
CNV is not a disease on its own but a complication of several eye conditions, most notably the "wet" form of age-related macular degeneration. Because leaking and bleeding can damage central vision quickly, CNV is an important cause of vision loss, and timely treatment can often preserve sight. The condition has become much more treatable in recent years thanks to injectable medicines that block the signal driving abnormal vessel growth. This is one reason that catching CNV early matters so much: prompt treatment can stop the leaking before it causes permanent scarring, while delay allows damage that cannot be undone.
Symptoms
Symptoms usually affect central vision and can come on over days to weeks.
- Distortion, where straight lines look bent or wavy
- Blurred or reduced central vision
- A dark, gray, or blank spot in the center of vision
- Colors appearing less bright
- Difficulty reading or recognizing faces
New distortion or a sudden change in central vision should be evaluated promptly by an eye specialist, because early treatment of CNV gives the best chance of saving vision.
Causes
CNV develops as a complication of conditions that damage the layers under the retina.
- Age-related macular degeneration: The "wet" form, seen in macular degeneration, is the most common cause.
- Severe myopia: High nearsightedness can lead to CNV, as in myopic maculopathy.
- Inflammation or injury: Eye inflammation, infection, or trauma can trigger abnormal vessel growth.
- Other retinal conditions: Certain inherited or acquired retinal diseases can be associated with CNV.
In each case, signals released by stressed retinal tissue encourage fragile new vessels to grow where they should not.
Risk Factors
- Age-related macular degeneration, especially the wet form
- High or pathologic myopia
- Older age
- A history of eye inflammation, infection, or injury
- A family history of macular disease
Diagnosis
An eye specialist diagnoses CNV using a detailed retinal examination and imaging.
- Dilated eye exam: To view the macula and look for fluid, blood, or membranes.
- Optical coherence tomography (OCT): A scan that detects fluid and abnormal tissue under the retina, and is used to follow treatment.
- Angiography: Imaging of the blood vessels, sometimes with a dye, to locate and characterize the leaking vessels.
- Amsler grid: A simple home tool that helps detect distortion in central vision.
Treatment
Treatment aims to stop the abnormal vessels from leaking and to preserve vision. Outcomes are best when treatment starts early.
- Anti-VEGF injections: The main treatment; medicines injected into the eye block the signal that drives vessel growth, reducing leakage and often improving or stabilizing vision. Repeated injections are usually needed.
- Photodynamic therapy: A light-activated medicine used in selected cases.
- Laser treatment: Occasionally used for vessels located away from the very center of vision.
- Treating the underlying condition: Managing macular degeneration, myopia, or inflammation that led to the CNV.
- Monitoring: Regular follow-up scans to guide ongoing treatment.
Prevention
CNV cannot always be prevented, but risk can be reduced and early detection improves outcomes:
- Have regular eye exams, especially if you have macular degeneration or high myopia
- Use a home Amsler grid to check for distortion if advised, and report changes promptly
- Do not smoke, which is linked to macular degeneration
- Eat a healthy diet and manage general health conditions
- Follow your eye specialist's monitoring and treatment plan
When to See a Doctor
See an eye specialist promptly if you notice:
- New distortion, where straight lines appear wavy or bent
- A new dark or blank spot in your central vision
- Sudden blurring or loss of central vision
- Colors looking faded compared with before
CNV can damage central vision quickly, so do not wait. Early anti-VEGF treatment offers the best chance of preserving sight.
Frequently Asked Questions
What is choroidal neovascularization?
It is the growth of abnormal, fragile blood vessels from beneath the retina that leak fluid or blood. When this occurs under the macula, it can distort and damage central vision. It is a complication of several eye conditions rather than a disease on its own.
What causes choroidal neovascularization?
The most common cause is the wet form of age-related macular degeneration. Other causes include severe myopia, eye inflammation, infection, injury, and certain retinal diseases. In each case, stressed retinal tissue triggers abnormal vessel growth.
How is CNV treated?
The main treatment is anti-VEGF injections into the eye, which block the signal that drives vessel growth and reduce leakage. Repeated injections are usually needed. Photodynamic therapy or laser are used in selected cases, along with treating the underlying condition.
Can vision be saved if CNV is treated early?
Yes. Early treatment, usually with anti-VEGF injections, often stabilizes or improves vision, while delay allows leaking and bleeding to cause permanent damage. This is why new distortion or central vision changes should be evaluated promptly.
What are the warning signs of CNV?
Watch for new distortion of straight lines, a dark or blank spot in central vision, sudden blurring or loss of central vision, and faded colors. An Amsler grid can help detect distortion at home. Report any of these promptly to an eye specialist.
References
- National Eye Institute (NEI). Age-Related Macular Degeneration.
- American Academy of Ophthalmology. Choroidal neovascularization.
- MedlinePlus, U.S. National Library of Medicine. Macular degeneration.
- National Library of Medicine, StatPearls. Choroidal Neovascularization.