The Four Stages of AMD

Victor Freitas

The human eye是一个奇妙的，繁琐的复杂的装置。然而，复杂性是以代价为例，而我们的眼睛是相对较小的器官，他们易于宣传疾病，从白内障和糖尿病视网膜病变为色盲，青光眼等。

一个特定的诊断年龄相关的黄斑变性，或AMD - 通常会引发患者的特殊恐惧。难怪：没有治疗AMD，其前面的“干”形式或更先进的“湿”阶段。（见下面的两者之间的差异。）但尽管其令人担忧的声誉，但是有很多原因诊断出乐观态度的条件。

Most patients will not suffer from advanced AMD, which can sometimes result in legal (although not complete) blindness, says Jayanth Sridhar, M.D., an assistant professor of clinical ophthalmology at the Bascom Palmer Eye Institute of the University of Miami's Miller School of Medicine in Florida. And with timely treatment, he says, "the majority of AMD patients maintain functional vision."

If you or someone you love has been diagnosed with AMD, understanding exactly how the disease develops can help you stay one step ahead. Here's what you need to know.

What Is the Macula?

The macula, put simply, controls our sharp, central vision. Part of the retina, it's located at the back of the eye and is packed with light-receptor cells. When the macula is damaged by AMD, whether suddenly or gradually, vision can blur, straight lines might appear wavy, and blind spots can develop in the center of one's field of vision. Left untreated the condition will, in almost all cases, impact activities that rely on central vision, including cooking, driving, reading, and even recognizing faces.

There is currently no consensus on why some people get AMD and others don't. According to the Mayo Clinic, "no one knows exactly what causes dry macular degeneration" but research suggests that both heredity and environmental factors play a part. Caucasians and people who are overweight, smoke cigarettes, are more than 50 years old, or have high blood pressure are at increased risk, as are those with a family history of the disease.

Dry AMD: Early Stage

"Dry" AMD is the most common form of the disease, affecting somewhere between 85% and 90% of patients. (According to the National Institutes of Health, approximately 11 million people in the United States have AMD, most over age 50.) Dry AMD usually progresses quite slowly; people can live with the condition for years without discomfort or symptoms that suggest they need treatment.

同时，该疾病标志着三个不同的阶段。"The vast majority of AMD patients start off with the dry form, which in its earliest stage is characterized by the build-up of drusen, or fatty deposits underneath the retina," says Priyatham Mettu, M.D., an ophthalmologist and retinal specialist at Duke Eye Center in Durham, NC. Drusen is basically a form of debris that accumulates either because the cells are sick, or because a patient's ability to clear the debris is failing, says Dr. Mettu. "At the earliest stage, about half of patients are asymptomatic—they don't really have a lot of vision problems," he adds.

The other half of early AMD patients, however, often have significant trouble seeing in low light, says Dr. Mettu: "What that means is that trying to read a menu in a dimly lit restaurant, for instance, can be a real challenge."

When they do occur, early symptoms might include dark or blank spots in the center of one's field of vision, or a dulling or dimming of colors–the result of light-receptor cells in or near the fovea, where visual acuity in the retina is highest, atrophying or dying off. Upon diagnosis, a doctor might recommend one of several "AREDS" (Age-Related Eye Disease Study) antioxidant supplements; two large clinical trials sponsored by the National Eye Institute in 1999 and 2006 showed that certain antioxidant vitamins and minerals helped slow progression of the disease.

干amd：中间阶段

的中间阶段干AMD为特征by larger-sized drusen. At this point, some patients might experience mild vision loss or might require, say, a brighter light while reading, but in the majority of cases, intermediate AMD is far from debilitating.

A quick primer on drusen, which are often described as either "hard" or "soft": Those characterizations are not, in fact, based on texture, but on the drusen's appearance. "Hard" drusen are small and well-defined; their presence in the retina indicates a lower risk of vision loss than the presence of "soft" drusen, which are larger, tend to cluster together and, according to the American Academy of Ophthalmology, have edges "that are not as clearly defined as hard drusen." Their larger size and their tendency to bunch together, especially near the center of the retina, can distort vision. A person with a few hard drusen has significantly less chance of losing some of her central vision from AMD in a five-year timeframe than a person with numerous, larger soft drusen.

最终，在中间干燥AMD的患者可能不会经历重大的视力丧失或戏剧性症状，但它们仍然增加了发展干燥AMD的先进阶段或开发湿AMD的风险，这两者都是合法的严重条件。

干amd：高级阶段

干燥AMD的晚期阶段也称为“地理萎缩”，其中FOVEA受到损害。盲点是在这个阶段的虚拟确定性，以及中央视力发挥关键作用的某些活动，例如阅读或识别面，可能变得越来越困难。

That said, certain techniques (learning to see objects using peripheral vision, for example, rather than relying on central vision) and behaviors (using specific types of light bulbs for reading) can help patientscounter some of this stage's more troubling manifestations。

As Dr. Sridhar notes: "Those who happen to have advanced dry AMD, which is about five percent of patients in the U.S, should know that there is a lot of encouraging treatment research going on today, including work with stem cell and gene therapies. And even in the worst-case scenarios, AMD does not typically result in total blindness unlike with other conditions we treat, such as glaucoma. Peripheral vision is almost always maintained, even with advanced AMD."

湿amd.

又称新生血管AMD，如果留下未处理的“湿”AMD可靠地引起比干形式更快速和更严重的视力损失。少数例外，湿AMD在疾病的中间阶段的后期或中间发展。（一小部分患者独立于干燥形式开发湿AMD。）

There's simple reason the two forms of AMD are described as dry and wet:

“当我跟病人about wet AMD, I describe a blood vessel sort of sneaking up from beneath the retina. In some ways that's a colloquialism, but it's also the reality," says Dr. Mettu. "We don't necessarily know when that vessel will form, or what part of the population is at greatest risk.

值得指出，这不是一个正常的船只流浪汉。这是从Retina的血管床上生长的病理学或异常血管。在生长时，它可以突破视网膜。它还可以泄漏液体，流血和瘢痕 - 所有对视网膜的光传感细胞都足够糟糕，它们可以受伤甚至死亡，这可能导致严重的视力丧失。“

最常见的症状之一？直线出现波浪或弯曲。当流体泄漏血管物理上抬起黄斑时，这可能会发生这种情况，扭曲视力。（图片墙壁上的涂料或天花板的方式有时会出现气球，当水泄漏的屋顶或管道池后面。）

Another aspect of wet AMD that sets it apart from dry is the speed with which it progresses. While the stages of dry AMD typically evolve slowly, over years or even decades, the wet form can, in some cases, develop with alarming rapidity. As the American Academy of Ophthalmology bluntly puts it: Wet AMD "is less common but much more serious" than dry. "You lose vision faster with wet AMD."

我们知道这听起来很可怕，但是所有这一切都有一些好消息：早期捕获时，湿AMD是可观的。被称为抗血管内皮生长因子（VEGF）的药物的靶向眼注射可以阻断在视网膜下方有“潜行”的异常血管的生长。是的，您需要直接交付的药物直接进入您的眼睛，但要记住的重要部分是它可以节省，有时甚至改善您的愿景。（需要更多帮助对这个想法感到舒服？我们有了建议。）

现在该做什么?看医生

记住：湿也不是AMD的干燥形式是你视线的死刑。但是，尽可能长，尽可能多地保留您尽可能多地保留您的愿景的唯一方法。

Meet Our Writer

Benedict Cosgrove

Benedict Cosgrove has been a writer and editor since the mid-1990s, working on sites ranging from Wired's Netizen to the National Magazine Award-winning LIFE.com. He has written for the New York Times, Washington Post, Los Angeles Review of Books, Columbia Journalism Review, Daily Beast, CNN.com, and others; editedCovering the BasesandGluttony(both from Chronicle Books); and is the author of没有什么难过的事情发生了。See more of his writing at bdcwrites.com.

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