Choroidal Neovascularization

This is just another name for wet age related macular degeneration. There are two types of age related macular degeneration - wet and dry. Wet macular degeneration gets its name from leaking blood vessels in the retina.

Choroid refers to one of the layers of the retina; neo means new and vascularization means blood vessels = new blood vessels growing from the choroid layer.

These abnormal blood vessels grow through the Bruch's membrane and into the subretinal space.

The choroid is the middle layer of the eye. It lies between the sclera and the retina.

The 4 main layers are:

1) The sclera

2) The choroid layer is made of small blood vessels that are responsible for carrying the nutrients to the back of the eye.

3) Bruch's Membrane is between the choroid and the Retinal Pigment Epitheliam (RPE), and acts as a filter between the RPE and choriocapillaries, keeping them separated.

4) Retinal Pigment Epithelium (RPE) transports metabolic waste from the photoreceptors across Bruch's membrane to the choroid.

The choroid layer contains most of the eye's blood vessels.These new, fragile and abnormal blood vessels grow up through the retinal layers.

The vessels are very fragile and break easily, causing blood and fluid to pool within the layers of the retina. Here is a picture of wet macular degeneration from the National Eye Institute.

Wet Macular Degeneration Symptoms

Wet macular degeneration symptoms include:

√ Blurred Vision

√ Distorted Vision

√ Blind or gray spot in the center of vision

The severity of the symptoms depends on:

1) the size of the CNV and

2) its proximity to the macula.

Wet Macular Degeneration Treatment

√ Size of the bleeding

√ Location of the bleed

√ Amount of time that has passed since symptoms first started

Treatment Options Include:

√ Subfoveal excision

√ Laser Photocoagulation

√ Photodynamic Therapy (PDT) which uses light from a low-voltage laser after an injection of Visudyne which is a light sensitive drug. The light from this type of laser coagulates the vessels.

√ Macular Degeneration Surgery

√ Use of Antiangiogenic Drugs - such as Macugen, Lucentis, and Avastin

Types of Choroidal Neovascularization

In classic CNV there is a very rapid leakage of blood and fluid under the retina, causing the surface of the retina to become elevated and uneven. The leakage may even break through some of the layers of the retinal tissue, damaging the retina and leaving blind spots in vision.

2. Occult Choroidal Neovascularization

The blood vessels with this type are "hidden" beneath the fovea and are not readily defined. This type involves a slower blood leak under the retina. Because it is more gradual and there is less fluid, the retina does not become as elevated and uneven as it does with classic CNV.

The vision loss with this type is slower.

The vast majority of wet cases are mainly occult or a mix of occult and classic.

Types of CNV Relative to the Fovea

1) Sub-Foveal - lesions that are directly under the fovea; the vast majority of wet macular degeneration cases are the sub-foveal type

2) Juxta-Foveal - lesions in areas other than the center of the fovea

3) Extra-Foveal - lesions that occur in areas of the macula other than the fovea

For More Information:

Go from Choroidal Neovascularization to Wet Macular Degeneration

Go from CNV to Macular Degeneration

Contact Leslie Degner, RN, BSN

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