Neovascular Age-Related Macular Degeneration (AMD): What to Know
Understanding Blood Vessel Formation in Wet AMD
Medically reviewed by Christine L. Larsen, MD
Neovascular age-related macular degeneration (AMD), also known as wet AMD, is a type of advanced eye disease. This version of AMD is caused by the growth of abnormal blood vessels behind your retina (the light-sensitive tissue at the back of your eye). Fluid from these vessels damages your macula, the part of your retina that controls your central vision (what you see straight in front of you).
Neovascular AMD ranks as the most common cause of blindness among older adults. While this type of AMD occurs in about 10% to 15% of all people with AMD, it leads to 80% of severe vision loss linked to AMD.
There is no cure for this type of AMD. Early detection and treatment can help slow its progress and reduce the amount of vision loss. The most common treatment involves the injection of special drugs into the affected eye(s). Laser therapy is sometimes combined with these drugs.
This article describes neovascular AMD and how it affects your eyes and vision. It also explains risk factors, treatments, and resources to help you manage vision loss.
Israel Sebastian / Getty Images
Neovascularization in Wet AMD
"Neovascularization" means "new blood vessels." In wet AMD, new blood vessels form and sprout in the choroid, a layer that contains blood vessels under your retina. New blood vessels develop when your retina produces too much of a substance called vascular endothelial growth factor (VEGF). This protein supports the growth of new blood vessels.
What Happens to Eyes
The new blood vessels that originate from the choroid are abnormal. They grow into your retina, where they leak fluid and red blood cells. This fluid causes a blister in your retina, which is usually flat. As the fluid remains in place, it can damage your retina by killing light-sensitive cells called photoreceptors. Photoreceptors convert light into signals that are sent to your brain.
Vision Effects
Fluid from abnormal blood vessels can cause a rapid and dramatic decline in vision. Vision effects can include the following:
Loss of central vision
Discomfort in areas of bright light
Difficulty adapting when moving from dark to light areas
Well-defined blind spots or gaps in your central field of vision
Perception of changes in shape, size, or color of objects directly ahead of you
Colors that appear less vibrant
Visual distortions, such as straight lines appearing wavy
Hazy vision
Learn More: Macular Degeneration: Timeline of Vision Loss Progression
Who Gets Neovascular AMD?
The reason that AMD occurs and progresses to neovascular AMD in some people is not clearly understood. While no specific cause exists for neovascular AMD, research indicates that certain risk factors can contribute to your chances of having it. Since neovascular AMD occurs as late-stage AMD, risk factors that contribute to disease progression can also increase your risk of neovascular AMD.
The following non-modifiable risk factors (risk factors that can't be changed) are among those linked to neovascular AMD:
Age: Advanced age represents the leading risk factor for neovascular AMD. While the risk for AMD increases for people over age 60, the incidence of the disease progressing to late AMD is highest for people older than 75.
Gender: Research indicates that there is a higher risk of neovascular AMD among the female sex.
Race: Several studies show that the diagnosis of neovascular AMD is higher among Whites than Blacks and Hispanics.
Iris color: Studies indicate that people with blue or hazel irises have a higher incidence of advanced macular degeneration than those with darker irises.
Hypertension and heart disease: Progression of AMD to neovascular AMD is linked with hypertension (high blood pressure). There may be a link between the factors that cause vascular changes in your eye and those that contribute to heart disease.
Hereditary and genetic links: Having a family member with AMD increases your risk of having the disease compared to people who have no family history of it. Several genes are also linked with the onset and progression of neovascular AMD.
Several modifiable risk factors can also contribute to your risk of developing neovascular AMD. These factors include the following:
Smoking: Research indicates that smokers have a risk of AMD that is 2 to 4 times higher than nonsmokers. Studies also show that the development of neovascular AMD is greater among smokers than nonsmokers, with the onset of neovascular AMD occurring 5.5 years earlier in smokers than those who never smoked.
Alcohol consumption: Research shows that people with a history of heavy drinking, defined as four or more servings of alcohol daily, have a higher risk of developing neovascular AMD vs. people who do not consume alcohol daily.
Diet and nutrition: Following a Western diet increases the risk of neovascular AMD, while following a Mediterranean/Oriental diet pattern is linked with a lower prevalence of AMD progression.
High BMI (body mass index): Excess body weight, defined by a high BMI, is linked with a 32% increase in the risk of late-stage AMD.
Non-neovascular AMD vs. Neovascular AMD
There are two types of age-related macular degeneration (AMD). They differ in the type of damage they cause and how they occur.
Non-neovascular AMD, or dry AMD, results when macular cells begin to thin and deteriorate. As these cells decompose, small pieces of cellular debris called drusen accumulate and cause gradual loss of central vision.
Neovascular AMD begins as non-neovascular AMD and occurs as a late-stage version of the disease. It is called wet AMD because vision loss occurs due to abnormal blood vessels that leak fluid into your retina. Vision loss from wet AMD can happen suddenly within days or weeks.
Treatments for Advanced Neovascular Wet AMD
Without prompt treatment, neovascular wet AMD can cause central vision loss. Vision loss can become permanent if wet AMD treatment does not begin within a few days to weeks from the start of symptoms.
The following treatments can't cure advanced neovascular wet AMD, though they may slow the rate of vision loss or stop further damage:
Anti-VEGF (Anti–Vascular Endothelial Growth Factor) Injections
Anti-VEGF injections are the first-line treatment for neovascular wet AMD. These injections deliver drugs that inhibit VEGF. This prevents the growth of abnormal blood vessels that can damage your macula.
Anti-VEGF injections help most people with neovascular AMD. About 33% of people treated with anti-VEGF therapy achieve improved vision, while 90% of those treated get at least stabilized vision.
Anti-VEGF treatments are given as intravitreal injections. This involves injecting the drug into your vitreous cavity (the space directly behind your eyes). Numbing eye drops reduce pain and discomfort. The procedure takes a few seconds.
Anti-VEGF injections are repeated initially about every four to six weeks, based on factors related to your condition and the drugs used. The span between treatments may be extended depending on how your eye responds.
While anti-VEGF treatments are effective, the need for frequent, ongoing injections can be a barrier to continued care and getting the best results. Though rare, side effects and eye damage can occur.
Anti-VEGF medications differ in how long they last in your eye. Your ophthalmologist will determine which medication is most appropriate for your condition. The medications used in anti-VEGF injections include:
Avastin (bevacizumab)
Beovu (brolucizumab)
Lucentis, Susvimo (ranibizumab)
Vabysmo (faricimab-svoa)
Each of these drugs is approved by the Food and Drug Administration (FDA) for treating neovascular AMD except Avastin. Avastin is FDA-approved as a targeted cancer therapy. Its use to treat neovascular AMD is considered off-label use. This is the practice of prescribing a drug for a different condition or at a different dosage than what it was FDA-approved for.
Prescribing a drug off-label is allowed by the FDA when physicians are well-informed about the product and studies have proven the drug is effective to be used in this way. While Avastin has similar efficacy and side effects, it costs much less than the other drugs.
Photodynamic Therapy
While anti-VEGF injections alone are effective for most people, a few cases of neovascular AMD achieve better results when the injections are used in combination with photodynamic therapy. Unlike anti-VEGF injections, photodynamic therapy alone does not improve vision.
This treatment involves the injection in the arm of verteporfin, a photosensitizing drug (a substance sensitive to the influence of radiant energy, namely light). The drug travels through your bloodstream to your eye. Your ophthalmologist shines a laser beam into your retina to activate the drug. When activated, verteporfin works to attack the abnormal blood vessels causing vision loss.
Based on your reaction to this treatment, photodynamic treatment may be necessary at three-month intervals.
Laser Photocoagulation
Laser photocoagulation is a type of minimally invasive laser surgery. It was the first treatment used for neovascular AMD. However, it is only appropriate for certain rare types of this disease in which abnormal blood vessels are not located beneath the center of your macula. It uses thermal laser treatments to seal or destroy leaking blood vessels.
Since laser photocoagulation also damages vision cells, it is only used when faulty blood vessels are located far from the center of your macula. A major problem with laser photocoagulation is recurrent choroidal neovascularization. This can occur in up to 60% of neovascular AMD treatments.
Emerging Therapies
Emerging therapies for neovascular AMD involve treatments that may provide options to those who require indefinite injections. Researchers are seeking to create therapies that are both effective and convenient so more people will comply with their treatment plans. These emerging therapies include the following:
Gene therapy: Gene therapy aims to provide a one-time injection treatment that helps your eye make its own anti-VEGF treatment.
Injection alternatives: Investigation into injection alternatives such as eyedrops and oral tablets may enable people to avoid inconvenient eye injections.
Port delivery system (PDS): The PDS uses an implanted device that continuously releases anti-VEGF drugs into your eye for up to two years. A surgical procedure is used to implant this device, which is smaller than a grain of rice.
Treatment for multiple causes of neovascular AMD: The FDA-approved drug Vabysmo targets neovascular AMD and diabetic macular edema, allowing up to four months between treatments.
Biosimilars: A biosimilar drug is a biological product that is highly similar to its FDA-approved reference product. It is similar in molecular effect and bioactivity but typically costs less. This can contribute to patient compliance. Several biosimilars are being developed for anti-VEGF medications.
Wet AMD Support and Vision Assistance
Living with wet AMD can be challenging. The vision impairment that AMD causes can occur dramatically and suddenly, leaving you little time to become accustomed to the change. Research indicates that people with wet AMD and their caregivers have a high risk of anxiety and depression.
Support groups can be a valuable source of information, encouragement, and social interaction as you navigate the changes that occur with wet AMD. Ask your eye specialist or general healthcare provider for referrals to local support groups that might include people with wet AMD.
You can also find many macular degeneration resources online. Look for national organizations that support people with vision problems and eye diseases. They often provide newsletters, news on the latest treatments, and tips for living with vision loss from wet AMD. Organizations relevant to wet AMD and related eye diseases include:
Macular Society (based in the United Kingdom)
Many national organizations sponsor local, online, or telephone-based support groups for people with vision loss. These support groups include:
State-specific mentoring and peer support groups supported by the American Council of the Blind (ACB)
State-specific support groups affiliated with MD Support
International Low Vision Support Group (ILVSG) TeleSupport, a program of free monthly group support sessions held over the telephone
State affiliates of the National Federation of the Blind
State-specific national/local services relevant to people with vision loss, provided by VisionAware
SightMatters, an online and Facebook community for people with AMD
Free live discussion groups from Hadley Vision Resources
Read Next: Coping With Macular Degeneration
Summary
Neovascular AMD is an eye disease that damages your central vision. It is an advanced form of AMD that can cause fast and severe vision loss without prompt and proper treatment.
Getting early treatment can help stabilize vision loss. It may also restore lost vision in some cases. Most people achieve results with anti-VEGF treatments if they follow the advised schedule of injections.
The physical changes that can occur with wet AMD can include emotional challenges. Resources like support groups can provide encouragement and education to help you meet the changes this disease can cause.
Read the original article on Verywell Health.
