- Diseases, Disorders & Conditions
Macular Degeneration Surgery – A Brief Introduction
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This hub reveals some of the basic knowledge and information about age related macular degeneration - such as its causes and diagnostic methods - as well as surgeries that are used to cure this disease. Person who does not have good eyesight will usually suffer from weakened self-confidence and decreased quality of life. Age related macular, or AMD in short, is a disease that can cause serious eyesight damage or even loss. As its name indicates, age related macular degeneration is a chronic disease closely related to aging, people usually experience progressive eyesight loss from a long period of time.
Usually, doctors use fundus examination to determine whether patients are suffering from macular degeneration, then use fundus fluorescein angiography (a diagnostic procedure that, by injecting a dye into the vein and taking photographs, is used to detect problems with your eyes ) to determine the nature of the disease for further treatment. Currently, compared with other eye diseases, macular degeneration surgeries are the more difficult.
What is the macula?
To better understand this disease, let's first try to understand some of the basic knowledge, such as what is macular. To put it in a simple way, the human’s eyes are like a camera, the retina is equivalent to the structure of the film, it is a thin layer with fine structure, which can feel the light projected on it, and pass the stimulation of visual signals to the brain, eventually forming vision. Macular is a soybean-size area in the central retina, it is rich in lutein (a yellow carotenoid pigment). Everybody has macula on his or her retina, It only accounts for about 5% of the entire retina, but has an important function. Typically, an eyesight test tests the visual sensitivity of macula. In the center of macula, there is a tip size shallow depression, known as foveal, which is an area where the most sensitive photoreceptors are located. Foveal is the most sensitive part of vision, it mainly plays the role of visual fine. The ability to distinguish among a variety of colors depends on the function of macular, besides, activities such as reading newspapers, watching TV and seeing distant objects all rely on macular in the central retina. Once there is damage to macular, the human central vision will be seriously decreased.
What is age related macular degeneration?
Age related macular degeneration is a common eye diseases in the elderly population, it can cause a sharp decline in central vision, and mostly occur in 45 years of age, it the main reason for severe vision loss among the people above 50 years of age, it is also one of the world's top disease that leads to adult blindness. Due to sharp declines in visual function, AMD patients can not drive, or read, or take a walk on the street, and suffers increased risks of falling and fractures because of poor eyesight, all of the above will lead to patients being increasingly dependent on the family and society. What’s more, patients with age-related macular degeneration suffer more from mental and emotional diseases, and they are more easily to have anxiety and depression.
Who is more likely to get age related macular degeneration?
All studies have shown that age is a major influencing factor, the greater the age, the higher the incidence of the disease. Among people age over 65, about 25% of the population are suffering from macular degeneration. Other factors include gene, sex, race, living habit and nutrition. For example, to a certain extent, people with a family history of AMD have higher incidence of the disease. People suffering from hypertension, diabetes, hypercholesterolemia and obesity have higher risk to get macular degeneration. And, people who has been diagnosed with AMD in one eye will very likely to develop the disease in the other eye in about 5 years.
Age related macular degeneration can be divided into two types: dry and wet forms, also called nonexudative and exudative forms. The dry form is generally considered a benign type, accounting for about 80% of the people diagnosed with AMD. The symptoms are slowly decreased visual acuity, or in severe occasion visual distortion. Fundus examination of dry form shows many round yellow dots - drusen.
The wet form, also known as exudative form, takes up approximately 20% of the total. It arises from the progress of serious wet form, it is characterized by abnormal retinal neovascularization (new vessels grow abnormally under the retina), such new vessels are easily to bleed. This type of macular degeneration has very significant vision loss, the abnormal growth of new blood vessels can cause retinal hemorrhage, exudation, edema and formation of scar, the organizational structure of retina will be destructed and vision will decrease rapidly. Compared with dry AMD, wet AMD progress more rapidly with more severe visual loss, and vision will be very difficult to restore once lost.
Diagnostic methods of macular degeneration
If decreased visual acuity, visual distortion and other anomalies are found, especially in elderly people, it is highly recommended that an eye medical checkup should be arranged with a doctor immediately. Fundus examination by a doctor can determine if people are having macular degeneration, and fundus fluorescein angiography can then determine the nature of macular degeneration. Fundus fluorescein angiography is done by intravenous injection of sodium fluorescein, and then over time, doctor will capture fundus photographs in different periods to determine nature of the disease.
Treatments of age related macular degeneration
Treatments of AMD are very limited, that’s why AMD is also considered to be one of the most difficult diseases to cure in ophthalmology. As the dry degeneration is a slow process, it is usually treated with drug therapy and nutritional intervention. By adding a lot of vitamin C, E, β carotene and trace elements such as zinc and copper in the long term, the development of the disease can be delayed.
Treatment of wet degeneration is even more difficult than the dry form. The treatment methods of wet AMD are mainly surgeries, they are laser photocoagulation, radiotherapy, surgery, transpupillary thermotherapy, photodynamic therapy and anti-angiogenesis drugs treatment, among them, laser photocoagulation and photodynamic therapy are two of the most effective treatments for macular degeneration, and they are widely used in clinical surgeries.
Laser photocoagulation surgery has been widely used in the treatment of many eye diseases for many years, and it proves to be a very effective surgery of AMD in some patients. Generally speaking, laser photocoagulation uses a high-focused laser beam to reach the ocular blood vessels, and achieves some treatment effects, such as stopping blood vessel leakage, to greatly reduce the progression of wet macular degeneration. However, this method is not without shortcomin, it is more suitable for patients whose blood vessel over-growth is outside of foveal (the center of macular), or the over-growth is with clear boundaries, which accounts only for about 20% of wet AMD patients. What’s more, according to some reports, patients who had laser photocoagulation surgery have 50% of new blood vessels persisting or relapsing within two years. In addition, laser photocoagulation treatment has also brought some non-selective damage to surrounding retina, resulting in unwanted vision decrease. This shortcoming of destruction of normal tissue has greatly limited its clinical application.
Photodynamic therapy, or PDT for short, is a new treatment, the surgery uses a specific photosensitizer as medium, the photosensitizer is injected into the blood vessel of the patients, and it can reach abnormal ocular blood vessels. Doctor will then use a special non-thermal laser (cold laser) to undermine the abnormal new blood vessels, without posing any damage to the normal tissues in the retina, thus reducing or delaying vision loss caused by wet macular degeneration. This is by far the most effective surgery for age related macular degeneration with least complications, However, the surgery is also the most expensive.
P.S. The specific photosensitizer used in PDT is called Visudyne (verteporfin), a patent drug from Novartis, it is by far the only FDA approved photosensitizer for ophthalmic treatment.