Published on August 1st, 2012 | by Mark Erickson
Choroidal neovascular membrane (CNVM)
Also called: Subretinal neovascular membrane (SRNVM), Choroidal neovascularization (CNV), Wet macular degeneration
What is CNVM?
Most commonly associated with wet macular degeneration, choroidal neovascular membrane (CNVM) involves the development of new, abnormal vessels below the retina, the light-sensitive multi-layered tissue that lines the back of the eyeball.
Macular degeneration and other retinal diseases, like myopic degeneration and ocular histoplasmosis can damage the important layers of the retina, compromising its ability to act as a barrier to the vascular layer below the retina, called the choroid.
Once the retinal layers are damaged by diseases like macular degeneration, the choroid can produce new blood vessels (neovascularization) which grow up through the damaged layers and leak or bleed into the retina. Once this happens, the vision can become blurry, darkened or distorted.
Since the retina acts as the “film in the camera” of the eye, any retinal irregularities in it can cause distortion, dark or fuzzy spots and loss of vision. If CNVM bleeds into the retina, the patient can experience dark or missing areas in the vision.
Using an Amsler grid daily is usually effective at picking up any early changes in the central macular area — a common location of CNVM lesions.
This helpful study will produce photographs of the retina that allow Dr. Deupree to confirm and identify the existence of and the exact location, type, shape and size of neovascular membrane.
The fluorescein angiography results will also help the doctor choose which treatment would be best for the particular patient and the photos will serve as documentation of the current state of the disease, allowing the doctor to follow and compare future study photographs. This series of dye tests will demonstrate the effectiveness of treatments and help the doctor decide if additional or alternative treatments should be done.
OCT is a non-invasive technology used for imaging the retina, the multi-layered sensory tissue lining the back of the eye. This technique provides highly detailed, high-definition maps and images of the macula and retinal structures. The existence of CNVM can be confirmed and followed with this non-invasive study. This allows Dr. Deupree to make the most accurate diagnosis possible.
Of the two main forms of macular degeneration, wet and dry, wet macular degeneration is the only form with known, proven treatments. Those treatments include: Laser photocoagulation, Photodynamic Therapy, Macugen, Lucents and Avastin injections.
Recently, the overwhelming treatment of choice throughout the vitreo-retinal medical community has been intravitreal anti-VEGF injections. These new medications target the underlying cause of CNVM in the “wet” form of macular degeneration. The abnormal blood vessels found in CNVM react to the medication by “drying up” after multiple injection applications. The results of these treatments has been very encouraging for macular degeneration patients.