What Is Neovascularization in the Eye?

Neovascularization refers to the growth of new blood vessels. The prefix neo means new, and vascular refers to vessels.

Neovascularization is associated with the growth of blood vessels that are part of abnormal tissue, such as tumors. With your eye health, neovascularization can be a sign of disease or certain eye conditions. Here is more information about the types of neovascularization related to eye health.

Corneal Neovascularization

Your cornea is the clear, dome-shaped front of your eye. The cornea helps to control light entry into the eye. It also protects your eyes from germs and dust.

Corneal neovascularization happens when new blood vessels come into the cornea from an area of the eye called the limbus. The new blood vessels can cause inflammation and scarring that affect your vision.

Corneal neovascularization can have several causes, including:

• A bacterial or viral infection
• Chemical burn
• Contact lens wear that causes hypoxia, or lack of oxygen to the eye
• Ocular herpes
• Trauma to the eye

Some treatments for cornea neovascularization include injections of certain medications to the eye and laser therapy. Gene therapy is another possible treatment for corneal neovascularization. It involves the transfer of treatment-focused genes to the eye. The treatments for corneal neovascularization have limitations. Researchers continue to try and find new ways to help this problem.

Diabetic Retinopathy

Diabetic retinopathy is an eye disease that can happen in people with diabetes. It occurs when blood vessels in the retina (the light-sensitive tissue in the back of the eye) are damaged by high blood sugar levels. That can cause blood vessels to close, leak, or swell.

In its more advanced form, diabetic retinopathy also can cause abnormal new blood vessels to grow on the retina. The new blood vessels can do several things:

• Bleed into the vitreous, which is a gel-like substance that fills the eye. The bleeding can cause floaters, or they may block all of your vision.
• Form scar tissue. The scar tissue can lead to problems with the area of the retina called the macula. It also can lead to a detached retina, which is a medical emergency.

Treatments for diabetic retinopathy include:

• Medications injected into the eye
• Better control of your diabetes. Good blood sugar control can help some of your lost vision to return.
• Laser surgery
• A procedure called a vitrectomy, which involves the removal of vitreous gel and blood from the vessels that have leaked.

Retinopathy of Prematurity (ROP)

Retinopathy of prematurity (ROP) is caused by the abnormal growth of retinal blood vessels in premature babies. It can lead to blindness.

There are different stages of ROP. At its mildest form, it can resolve on its own and not lead to retinal damage. When it is severe, it can lead to the retina detaching from the eye and may cause blindness. However, most ROP resolves without causing damage.

Treatments for ROP include laser ablation and injection of medication into the eye to stop abnormal blood vessels from developing. Still, some eyes with retinopathy of prematurity continue to have permanent or severe vision loss. 

Age-related Macular Degeneration

Age-related macular degeneration (AMD) is an eye disease associated with aging. Dry AMD is an early form of the disease, and wet AMD is a more advanced form. The more advanced form is also called advanced neovascular AMD.

Wet AMD occurs when vascular endothelial growth factor (VEGF), which is a type of protein, leads to the growth of abnormal blood vessels where they should not grow in the back of the eye.

Treatments for wet AMD include:

• Injections of anti-VEGF into the eye
• Photodynamic therapy, which involves the use of a light-sensitive medicine called verteporfin that activates when hit by a specific type of laser. Photodynamic therapy is not used as often as anti-VEGF injections.
  

Choroidal Neovascularization

The choroid of the eye is a layer of tissue located between the sclera, or the eye's white outer layer, and the retina.

The choroid has blood vessels that supply oxygen and nutrients to the eye. Choroidal neovascularization is the formation of abnormal blood vessels that begin in the choroid in a person who has wet age-related macular degeneration. When a person with AMD makes too much VEGF, new blood vessels can grow from the choroid and into the retina.

Those additional blood vessels may:

• Leak
• Allow fluid from the blood or red blood cells to enter the retina. This fluid can harm the retina and kill off cells called photoreceptors, which are light-sensing cells.
• Change vision

Treatment for choroidal neovascularization involves injections of anti-VEGF medications into the eye.

Summary

Neovascularization refers to the formation of new blood vessels. In some cases and with certain diseases, the formation of new blood vessels can interfere with your vision. These include:

• Corneal neovascularization
• Diabetic retinopathy
• Retinopathy of prematurity
• Age-related macular degeneration
• Choroidal neovascularization

A Word From Verywell

When it comes to your eye health, the growth of abnormal blood vessels can get in the way of how you see. Let an eye doctor know if you have a change to your vision and you are not sure what is causing it. The eye doctor can perform exams to check for the growth of abnormal blood vessels or other causes of vision problems.