Definition: Choroidal neovascular membrane is a sign of many different retinal diseases, but is most commonly associated with Age Related Macular Degeneration. CNVM causes abnormal blood vessels to grow from the tissue layer just beneath the retina up through the retinal layers. Imagine these abnormal blood vessels as roots growing up through a sidewalk, breaking and buckling the surface. These new vessels are very fragile and break easily, causing blood and fluid to pool between the retinal layers. As the vessels leak, they deform the delicate retinal tissue and decrease vision.
Symptoms: Ranging from mild, such as blurred or slightly distorted vision, to severe, as grayed-out areas of vision or a central blind spot.
Detection of CNVM can be done with a simple test called an Amsler Grid. This helps the doctor determine location and severity. CNVM is diagnosed through a dilated eye exam followed by a diagnostic imaging procedure called fluorescein angiography.
Treatment: Treatment depends upon several factors: size and location of the abnormal blood vessel membrane, and the amount of time since the symptoms began. If it is small, compact, and caught early, a delicate operation can be done to remove it. This surgery has the most risk, but offers the best chance of vision improvement afterward.
A laser procedure that seals the leaking blood vessels is the simplest and most common treatment for CNVM. It is reserved for patients with bleeding outside the center of the retina because it can create a scar that affects the vision. Treating with laser gives the surgeon the most control over scar placement and size. Allowing a leak to resolve on its own is often more devastating to the vision.
Unfortunately, sometimes no treatment is appropriate. All CNVM patients should monitor their vision with an Amsler Grid at home and report changes to their doctor immediately.