Your Complete Guide to AMD Testing

Amsler grid as it might appear to someone with age-related macular degeneration./National Eye Institute, National Institutes of Health

In just the过去几十年间,多样性和复杂性of the ways we test for age-related macular degeneration (AMD) have grown tremendously. And while there is no cure for the condition—or rather, there is no cureyet-早期发现这种疾病的“干”和“湿”形式可以帮助医生和患者可靠地管理AMD，在某些情况下可以减缓其进展。

No one knows exactly what sparks the process behind the more common, dry form of macular degeneration. (We do know that the sudden emergence of abnormal blood vessels that leak into the retina causes wet AMD, but why they erupt in the first place is not thoroughly understood.) As for those most at risk, the data are clear: Caucasians and people who are over 50 years old, are overweight, smoke cigarettes, have high blood pressure, and/or have a family history of the disease should be especially vigilant. Scientists have identified genetic variants that are at higher risk for developing AMD. Symptoms include, but are not limited to, an onset of blurry eyesight, a dimming of colors, straight lines appearing wavy, and blind spots in one's central field of vision. In addition, distortion in vision; either straight lines appearing wavy or sometimes images appear as if one is “looking through water.” as well as blind spots are in the center of the vision. When reading, letters in words seem to be missing. Those with macular degeneration will also complain of difficulty adapting in the dark.

如果你或你爱的人有患AMD的风险，了解评估该风险或诊断病情本身的各种测试方法，对管理非理性（甚至理性）恐惧有很大帮助。以下是需要记住的测试。

AMD: Risk-Factor Tests

While the following are not considered diagnostic tools, they can help doctors and patient alike assess the risk some people face of developing AMD.

Macular Pigment Optical Density Test:MPOD is a non-invasive way to determine the level of two naturally occurring pigments, lutein and zeaxanthin, in our eyes. Both pigments help block "blue light"—for example, from digital devices—which might damage eyes over time. (The National Institutes of Health notes that while there have been “many studies on blue light's effects on the retina,” the data “are still being debated.”) Low levels of either or both pigments, meanwhile, might indicate an increased risk of AMD.

家族史：了解AMD家族史（或缺乏AMD家族史）有助于确定检测和治疗过程。根据美国国立卫生研究院的说法，“AMD的风险大大增加，因为一级亲属受到影响…[and]AMD患者应建议兄弟姐妹和儿童在出现症状时立即寻求眼科建议。换句话说，如果父母或兄弟姐妹被诊断患有AMD，则应告知其他兄弟姐妹或儿童及其医生，以便他们可以采取相应的行动并进行检测。

AMD: Visual-Performance Tests

在AMD的早期阶段，视力很少受到影响。然而，这些测试可以帮助医生和患者监测疾病的潜在进展。

Amsler Grid:Named for the Swiss ophthalmologist who devised it, the Amsler grid has been a standard test for AMD and other central-vision ailments since the 1940s. It consists of a simple grid of horizontal and vertical lines, with a prominent dot in the middle. Depending on what a patient sees—straight lines vs. wavy/curvy—the grid can help detect, or at least suggest the presence of, disturbances in the retina and macula. (In wet AMD, particularly, even a minuscule leakage of blood or other fluid from swollen or compromised vessels can interfere with central vision, distorting images, causing straight lines to appear wavy or missing, etc.)

正如医学博士贾扬斯·斯里达尔（Jayanth Sridhar）所描述的那样，网格“简单而美丽”斯里达尔博士是迈阿密大学米勒医学院巴斯科姆-帕尔默眼科研究所的临床眼科助理教授，阿姆斯勒不仅仅是一个棋盘。“这是一个非常可靠、非常敏感的测试，”他说。“当然，围绕阿姆斯勒的一个问题是，它的效果取决于用户对他或她看到的东西的解释。但我认为几乎任何人都可以看到直线，并判断它们看起来是否弯曲。”

对比敏感度：Difficulty distinguishing between objects or textures with low contrast (black coffee in a dark mug, for example) is often an early symptom of AMD. Contrast sensitivity testing, of which there are a few different types, essentially gauges how well or how poorly the eyes distinguish between fine light increments, according to a study in the journal眼科与视觉科学研究例如，佩利-罗布森测试（Pelli-Robson test）的特点是，图表中的大写字母沿水平线排列，每个字母及其背景的对比度在每一步都会降低。

ERG：Early AMD can also bring about seemingly contradictory symptoms, such as an increased sensitivity to glare and/or an increased difficulty reading or functioning in dim light. An electroretinography (ERG) test, or electroretinogram, can help gauge light receptivity by measuring the electrical response of the eyes’ light-sensitive cells—the rods and cones. During the test the doctor will dilate the patient's eyes with eye drops and numb them with anesthetic drops. With a flashing light, the doctor then measures the retina's electrical response to light, thus determining the relative light sensitivity in the eye.

视野：According to the American Academy of Ophthalmology, “Visual field testing is one way your ophthalmologist measures how much vision you have in either eye and how much vision loss may have occurred over time.” The Visual field test basically maps blind spots. Those with macular degeneration will have blind spots in the center of their vision. The patient will look into a large bowl called a perimeter and press a button when he/she sees flashing lights. The computer will track where a patient misses the flashing lights and map out the blind spots.

AMD: Diagnostic Tests

眼睛本身的直接观察测试仍然是确定AMD的存在或进展的标准

眼底检查：与ERG一样,这次考试涉及到扩张的e pupils, so that the physician, using a special viewing instrument, can examine the back of the eye. The doctor is looking for evidence of drusen—tiny, yellow, fatty-protein deposits that form under the retina and, in large numbers, can damage light-sensitive cells. People with macular degeneration often have significant numbers of drusen, especially of the "soft" variety, which tend to be larger and potentially more threatening than “hard” drusen.

北卡罗来纳州达勒姆杜克眼科中心的眼科医生和视网膜专家Priyatham Mettu医学博士指出：“大量的软drusen往往表明风险较高，而较小的硬drusen往往风险较低。”Mettu博士还指出，drusen的“软”和“硬”特征与其说是这些沉积物的物理组成，不如说是它们的外观。硬德鲁森在视觉上更清晰或更清晰，而软德鲁森则不太清晰，边界不规则，形状不规则。

Fluorescein Angiography:Colored dye injected into a vein in the arm travels to the blood vessels in the eye and highlights them. A doctor or technician uses a specially designed camera to take pictures as the dye journeys to the vessels. These pictures show if a patient has experienced abnormalities in blood vessels (their shape or size) or other parts of the retina (typically newly formed blood vessels that leak fluid underneath the retina), which might indicate wet AMD.

光学相干层析成像：OCT is a noninvasive test that returns detailed, cross-sectional pictures of the retina, and indentifies areas of thickening, swelling, or thinning of the macula and other retinal parts. It is also, from a technical perspective, one of the wonders of the ophthalmologist's diagnostic toolkit. OCT has become the gold standard in the diagnosis of AMD.

梅图博士说：“二三十年前，我们对AMD的理解主要来自直接检查：观察眼睛内部并拍照，然后我们可以进行研究。”。但OCT“通过提供高分辨率、显微镜水平的视网膜结构和横截面可视化，彻底改变了我们描述疾病的方式。这使我们能够更早地看到疾病并评估其相对严重性。

“事实上，我们现在才开始意识到我们的成像技术在筛查和监测现有疾病方面的威力。真正令人兴奋的是，OCT和其他成像方法非常适合计算科学和人工智能算法，它们可以自动检测疾病。这将使我们能够在更高层次上筛查疾病。”大量的患者，我们将能够更高效、更便宜地完成这项工作。"

无论是老式的阿姆斯勒网格还是尖端的OCT机器，用于检测和监测年龄相关性黄斑变性的测试都有一个原因：因此患者将利用它们。尽早、经常去看眼科医生。

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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; edited掩护基地and暴食(both from Chronicle Books); and is the author ofNothing Bad Ever Happens. See more of his writing at bdcwrites.com.

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