Expert

What is Choroidal Neovascularization?

Scheie Eye Institute, University of Pennsylvania
Image of the retina showing a region of choroidal neovascularization associated with wet ager-related macular degeneration
Courtesy of the National Eye Institute, National Institutes of Health
Photo of the back of the eye/retina with the arrow pointing to the dark reddish choroidal neovascularization
Learn what choroidal neovascularization is, why it occurs, how it is diagnosed, and options for treatment.

Some patients with dry age-related macular degeneration (AMD) eventually develop “wet AMD,” in which abnormal blood vessels grow into the retina and leak fluid, making the retina “wet.” Technically, this is called CNV or choroidal (core-oyd-al) neovascularization (nee-oh-vas-kyoo-lar-eye-zay-shun).

What Does Choroidal Neovascularization Mean?

“Neovascularization” means “new blood vessels.” These new, abnormal blood vessels originate in the choroid, a vessel-containing layer under the retina. When the retinas of people with AMD produce too much vascular endothelial growth factor (VEGF), new blood vessels sprout from the choroid, then grow into the retina. The new vessels, unlike normal ones, are leaky, and they allow fluid from the blood, and sometimes even red blood cells, to enter the retina. This fluid can immediately distort the vision because it forms a “blister” in the retina, which is normally flat. Over the course of days to months, this fluid can damage the retina, killing the light-sensing cells, called photoreceptors.

Symptoms of Choroidal Neovascularization

The symptoms of CNV include a distortion or waviness of central vision or a gray/black/void spot in the central vision. This should prompt a call to an ophthalmologist right away to get a priority emergency visit. The ophthalmologist can halt the growth and leakage of the blood vessels by injecting a drug blocking a protein called VEGF into the eye, but only if they can deliver the drug as soon as possible, within hours or days or so from the time you notice the change in vision. Time lost is vision lost!

Diagnosing Choroidal Neovascularization

The ophthalmologist can detect CNV using a combination of techniques. First, during the dilated eye exam, she/he may see a blister of fluid or bleeding in the retina. Then, using specialized imaging called optical coherence tomography (OCT), a cross-section picture of the retina is obtained. This image can detect even small amounts of fluid that have leaked into the retina from CNV. 

Additional imaging techniques called fluorescein or ICG angiography involve injection of a dye into a vein somewhere else in your body (where the dye gradually diffuses into the vessels in the back of the eye), followed by retinal imaging that shows the dye leaking from the blood vessels into the retina. These images sometimes provide additional information about the CNV.

Conditions That May Cause Choroidal Neovascularization

  • Age-related macular degeneration is the most common disease causing CNV, but other diseases that “stress” the retina, causing it to produce excess VEGF, or disrupting the barrier between the retina and choroid, can also cause CNV.
  • In patients with pathologic myopia (extreme nearsightedness), the eye is longer than normal, and this lengthening stretches and stresses the retina.
  • Ocular histoplasmosis is a fungal infection that can cause CNV.
  • Eye trauma and angioid streaks (small breaks in one of the retina’s layers) can break the barrier between the retina and choroid, resulting in CNV.
  • Severe ocular inflammation, a condition called uveitis, can also cause CNV.

Most patients with these diseases benefit from injection into the eye of anti-VEGF drugs (Lucentis®, Eylea®, or Avastin®), since VEGF promotes the CNV growth and leakage in most cases.

New research is bringing longer lasting anti-VEGF drugs, like brolucizumab, and anti-VEGF gene therapy, which should enable the anti-VEGF effect to last longer, so patients will not need to have injections as frequently.

Resources:

 

This content was first posted on: September 3, 2019

The information provided here is a public service of the BrightFocus Foundation and should not in any way substitute for personalized advice of a qualified healthcare professional; it is not intended to constitute medical advice. Please consult your physician for personalized medical advice. BrightFocus Foundation does not endorse any medical product, therapy, or resources mentioned or listed in this article. All medications and supplements should only be taken under medical supervision. Also, although we make every effort to keep the medical information on our website updated, we cannot guarantee that the posted information reflects the most up-to-date research.

These articles do not imply an endorsement of BrightFocus by the author or their institution, nor do they imply an endorsement of the institution or author by BrightFocus.

Some of the content may be adapted from other sources, which will be clearly identified within the article.

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