Wednesday, October 2, 2019
Choroidal Neovascularization :: Biology Essays Research Papers
Choroidal Neovascularization If you had to give up one of your five senses, which would it be? Would you give up your ability to see? A startling number of people lose their eyesight due to an eye disorder known as choroidal neovascularization. And soon I may be one of them. Although there is no known cure for this unfortunate disease, studies have been conducted to find the appropriate surgical treatment. The outer portion of the 2.5 cm human eye is composed of three primary layers of tissue. The outermost layer is called the sclera, which acts as a protective coating. Within this layer the transparent cornea is present in the front area of the eyeball. Under the sclera is the choroid where the majority of blood vessels and the iris are located. The light-sensitive layer is known as the retina. As mentioned, the choroid contains most of the eyeball's blood vessels. It is also the layer prone to bacterial and secondary infections. Choroidal neovascularization is a process in which new blood vessels grow in the choroid, through the Bruch membrane and invade the subretinal space. 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. Three main diseases that cause choroidal neovascularization are age-related macular degeneration, myopia and ocular trauma. The Wisconsin Beaver Dam Study 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, another cause of choroidal neovascularization, is for reasons unknown found more often in males than females. 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. Among soft contact lens wearers choroidal neovascularization can be caused by the lack of oxygen to the eyeball. Unlike age-related macular degeneration, age is irrelevant to this cause. Although no medical treatments have proven to be a cure for choroidal neovascularization, particular antiangiogenic substances such as thalidomide, angiostatic steroid, and metalloproteinase inhibitors are currently being tested. 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.