Choroidal Neovascularization

Blindness is the inevitable result of this choroidal neovascularization.

Choroidal neovascularization is a process in which new blood vessels grow in the choroid (the area of the eye containing most blood vessels), through the Bruch membrane and invade the subretinal space.

Parts of the Retina

The retina can be thought of as having 4 different layers. The choriocapillaries that form the choroids are responsible for carrying the nutrients required by the cellular layers above them. The Bruch membrane lays between choriocapillaries and the Retinal Pigment Epitheliam (RPE), and acts as a filter between the RPE and choriocapillaries, keeping them in effect separated.

The choroid layer contains most of the eyeball's blood vessels. It is also the layer prone to bacterial and secondary infections. Because there is currently no medical treatment for this disease this abnormal growth can easily lead to the impairment of sight or complete loss of vision.

Related Diseases

Three main diseases associated with choroidal neovascularization are age-related macular degeneration, myopia and ocular trauma. Among soft contact lens wearers choroidal neovascularization can be caused by the lack of oxygen to the eyeball.

In choroidal neovascularization patients, the fluid and blood along with the formation of new blood vessels form scar tissues which are trying to repair damages but are ultimately the cause of vision loss and possibly blindness.

Symptoms may include: seeing flickering or blinking lights in the affected eye or eyes, blurred vision, loss of vision.

The actual cause of the choroidal neovascularization is not typically known. Three main diseases associated with choroidal neovascularization are age-related macular degeneration, myopia and ocular trauma. Though among soft contact lens wearers choroidal neovascularization can be caused by the lack of oxygen to the eyeball.

Macular Degeneration

The Wisconsin Beaver Dam Study funded by the National Institute of Health showed that 1.2% of 43-86 year old adults with age-related macular degeneration developed choroidal neovascularization. The study also proved that choroidal neovascularization was caused by myopia in 5-10% of myopes.

Ocular Trauma

Ocular trauma is another cause of choroidal neovascularization. More than 50 eye diseases have been linked to the formation of choroidal neovascularization. Even though most of these causes are idiopathic, among the known causes are related to degeneration, infections, choroidal tumors and or trauma.

Although at present there is no cure for choroidal neovascularization, particular antiangiogenic substances such as thalidomide, angiostatic steroid, and metalloproteinase inhibitors are currently being tested to try to lessen or prevent the growth of the new blood vessels in the eyes.

Through surgical testing, partial removal of choroidal neovascularization proved to be useless. Therefore the focus has been placed on photodynamic therapy, a procedure approved by the Food and Drug Administration.

Photodynamic therapy is a treatment meant to stop the fluid as well as stunt further growth of the blood vessels among patients. Photodynamic therapy is performed in two phases. In the first phase Visudyne, a special dye that only attaches itself to abnormal blood vessels underneath the retina, is injected. Then a laser which does not damage the retina activates a compound which closes the anomalous blood vessels located in the eye. CNV has been seen to disappear 24 hours after the procedure. Unfortunately, CNV has also been seen to reappear 2-3 months later in almost all the patients and long-term benefits are still unknown. However, in a year-long Treatment of Age-related Macular Degeneration study of 609 patients16% of treated patients and 7% of placebo patients had visual improvement.