Choroidal Neovascularization (CNV) is a major cause of vision loss and is the creation of new blood vessels in the choroid layer of the eye. The choroid supplies oxygen and nutrients to the eye. CNV is a common cause of vision loss. The most common cause of CNV is from age-related macular degeneration.
In younger patients, neovascularization occurs primarily in the presence of cracks within the retinal macular tissue known as lacquer cracks when associated with myopic degeneration and extreme myopia.
Symptoms of Choroidal Neovascularization:
- Colors lose their brightness or colors appear differently in each eye
- Metamorphopsia – distorted vision, straight lines appear bent, crooked or irregular
- Loss of vision without pain
- Paracentral or central scotoma – is an island of relative or absolute vision loss in the center or near the center of vision.
- Sizes of objects may appear different for each eye
- Flashes of light or flickering in central vision
Clinical examination, fluorescein angiography and OCT (optical coherence tomography) are used to diagnose CNV.
Treatment for choroidal neovascular membranes depend on the underlying disease. You may receive one or more of these treatments depending on the progress of your disease.
Vascular endothelial growth factor “VEGF” causes abnormal blood vessels to grow under the retina. With anti-VEGF treatment, a drug is used to block the trouble-causing VEGF that reduces the growth of CNVM, slows leakage, and helps to improve vision or stop vision loss. Anti-VEGF is administered directly into your eye in an outpatient procedure. Multiple injections may be given over the course of many months and repeat anti-VEGF treatments may be needed for continued benefit.
Photodynamic therapy (PDT)
PDT also uses a laser and a combination of a photosensitizer (light-activated drug) and a special low-power, or cool, laser to target the CNVM. The photosensitive drug reaches the abnormal vessels by being injected into a vein in your arm. The low-power laser light activates the photosensitive drug to cause damage to the unwanted blood vessels. Multiple treatments may be necessary. This may be done in patients that are unresponsive to Anti-VEGF injections.
Thermal laser treatment
Thermal laser treatment is used to destroy the abnormal blood vessels, prevent further leakage, bleeding and growth – although the abnormal blood vessels are destroyed using laser treatment, re-treatment may be needed. This was the first proven treatment but is rarely used today.