Age-related Macular Degeneration (AMD) is a common eye condition that affects central vision. This progressive disease impacts the macula, the part of the retina responsible for sharp, detailed central vision. While AMD can manifest in different forms, neovascular AMD, often referred to as wet AMD, represents a more severe type. It is characterized by the abnormal growth of blood vessels, specifically Choroidal Neovascularization (CNV), which actively causes vision loss.
Understanding Neovascular AMD
Neovascular AMD involves the irregular growth of new, fragile blood vessels from the choroid, a layer of blood vessels beneath the retina, into the retina. This process is known as Choroidal Neovascularization (CNV). These newly formed vessels are often dysfunctional and leaky, allowing fluid and blood to accumulate in the macula. This leakage directly damages the light-sensing cells, called photoreceptors, leading to distortion and loss of central vision.
The macula is a small, specialized area within the retina. The choroid, situated behind the retina, supplies blood and nutrients to the outer layers of the retina. The “active” component of CNV refers to the ongoing leakage and proliferation of these abnormal vessels, which can lead to rapid and significant visual impairment compared to dry AMD, where vision loss typically progresses more slowly due to the breakdown of macular cells.
Recognizing the Signs
Individuals with neovascular AMD may experience a range of symptoms that often appear suddenly. A common symptom is distorted vision, where straight lines might appear wavy or bent, a phenomenon known as metamorphopsia. This visual distortion occurs because the fluid accumulation beneath the retina disrupts the macula’s normal, flat surface.
Another indication is blurry central vision, which can manifest as a dark or blind spot in the center of the visual field. Patients might also report a decrease in the intensity or brightness of colors. To help monitor for these changes at home, a simple tool called the Amsler grid can be used. This grid consists of a pattern of straight lines with a central dot; any new waviness, missing areas, or distortion when focusing on the dot could signal active CNV.
How It’s Diagnosed
Diagnosing neovascular AMD with active CNV involves a comprehensive eye examination by an ophthalmologist. This examination includes tests to assess visual acuity and pupil dilation for a clearer view of the retina. These initial steps help evaluate the overall health of the eye and the extent of any vision changes.
Specialized imaging techniques are then employed to confirm the presence of CNV and its activity. Optical Coherence Tomography (OCT) is a non-invasive scan that provides cross-sectional images of the retina, allowing the ophthalmologist to detect fluid accumulation, swelling, and structural changes within and beneath the macula. Fluorescein Angiography (FA) involves injecting a dye into a vein, which then travels to the eye, highlighting blood vessels in the retina and choroid as images are taken. This technique helps visualize leaking blood vessels, confirming the presence and location of active CNV. In specific cases, Indocyanine Green Angiography (ICGA), which uses a different dye and light wavelength, may be performed to provide additional details about choroidal circulation and to identify certain subtypes of CNV that may be difficult to see with FA alone.
Treatment Approaches
The main treatment for neovascular AMD involves anti-vascular endothelial growth factor (anti-VEGF) injections. These medications, such as ranibizumab, aflibercept, and bevacizumab, are administered directly into the vitreous cavity of the eye. Anti-VEGF therapy blocks VEGF, a protein that promotes abnormal blood vessel growth and increases their permeability. By inhibiting VEGF, these injections reduce leakage and prevent further vessel proliferation, stabilizing vision and often improving it.
The injection procedure is performed in a clinical setting by an ophthalmologist. The eye is numbed with topical anesthetic, and an instrument may be used to keep the eyelids open. The medication is then injected into the white part of the eye using a very thin needle. Patients may feel slight pressure but do not experience significant pain. While anti-VEGF injections are highly effective, they often require repeated treatments at regular intervals, such as monthly or every few months, depending on the individual’s response and disease activity.
Less common or older treatments for neovascular AMD include Photodynamic Therapy (PDT) and laser photocoagulation. PDT involves injecting a light-sensitive drug into the bloodstream, which then accumulates in the abnormal blood vessels. A cold laser is then used to activate the drug, causing it to seal off the leaky vessels. PDT was an earlier treatment option, but its use has decreased with more effective anti-VEGF therapies. Laser photocoagulation, which uses a hot laser to destroy abnormal blood vessels, is generally not used for CNV that affects the central macula due to the risk of creating a permanent blind spot. These older treatments are now largely reserved for specific cases where anti-VEGF therapy may not be suitable or as an adjunct therapy.
Living with Neovascular AMD
Managing neovascular AMD requires ongoing care. Regular follow-up appointments with an ophthalmologist are important to monitor disease activity and adjust treatment as needed. This continuous monitoring helps ensure that any recurrence of leakage or new vessel growth is addressed promptly to preserve vision.
Lifestyle adjustments can also support eye health. Adopting a healthy diet rich in fruits and vegetables is beneficial. Some individuals may benefit from specific dietary supplements, such as the AREDS2 formulation, which has been shown to help slow the progression of intermediate AMD to advanced forms, including wet AMD. Smoking cessation is advised, as smoking significantly increases the risk and progression of AMD. Additionally, protecting eyes from harmful UV light with sunglasses can be helpful.
While central vision loss can occur, low vision aids, such as magnifiers and specialized electronic devices, can assist individuals in performing daily tasks and maintaining independence. Support groups and resources are also available to help people adapt to vision changes and navigate living with neovascular AMD. With ongoing medical care and proactive lifestyle choices, individuals can work towards managing the condition and preserving their quality of life.