Published: 10 February 2026

Age-related macular degeneration, often called ARMD or AMD, is the leading cause of vision loss among Americans 65 and older. AMD causes damage to the macula, which is the central portion of the retina responsible for sharp central vision. AMD doesn't lead to complete blindness because peripheral vision is still intact, but the loss of central vision can interfere with simple everyday activities such as reading and driving, and it can be very debilitating. Types of Macular Degeneration There are two types of macular degeneration: Dry AMD and Wet AMD. Dry (non-exudative) macular degeneration constitutes approximately 85-90% of all cases of AMD. Dry AMD results from thinning of the macula or the deposition of yellow pigment known as drusen in the macula. There may be gradual loss of central vision with dry AMD, but it is usually not as severe as wet AMD vision loss. However, dry AMD can slowly progress to late-stage geographic atrophy, which can cause severe vision loss. Wet (exudative) macular degeneration makes up the remaining 10-15% of cases. Exudative or neovascular refers to the growth of new blood vessels in the macula, where they are not normally present. The wet form usually leads to more serious vision loss than the dry form. AMD Risk factors Age is the biggest risk factor. Risk increases with age. Smoking. Research shows that smoking increases your risk. Family history. People with a family history of AMD are at higher risk. Race. AMD is more common in Caucasians than other races, but it exists in every ethnicity. Gender. AMD is more common in women than men. Detection of AMD There are several tests that are used to detect AMD. A dilated eye exam can detect AMD. Once the eyes are dilated, the macula can be viewed by the ophthalmologist or optometrist. The presence of drusen and pigmentary changes can then be detected. An Amsler Grid test uses pattern of straight lines that resemble a checkerboard. It can be used to monitor changes in vision. The onset of AMD can cause the lines on the grid to disappear or appear wavy and distorted. Fluorescein Angiogram is a test performed in the office. A fluorescent dye is injected into the arm and then a series of pictures are taken as the dye passes through the circulatory system in the back of the eye. Optical coherence tomography (OCT) is a test based on ultrasound. It is a painless study where high-resolution pictures are taken of the retina. Article contributed by Jane Pan M.D.

Published: 02 February 2026

One of the most commonly asked questions in an eye exam comes right after the refraction, or glasses prescription check: “What is my vision?” Almost invariably, people know the term “20/20”. In fact, it’s a measure of pride for many people. “My doctor says I have 20/20 vision.” Or, on the other side of that same coin, having vision that is less than 20/20, say 20/400, can be a cause of great concern and anxiety. In this discussion I will describe what these terms actually mean. To lay the foundation, let’s discuss some common terms. Visual acuity (VA) is clarity or sharpness of vision. Vision can be measured both corrected (with glasses or contact lenses) and uncorrected (without glasses or contact lenses) during the course of an eye exam. The result of an eye exam boils down to two different but related sets of numbers: your VA and your actual glasses prescription. The notation that doctors use to measure VA is based off of a 20-foot distance. This is where the first 20 in 20/20 comes from. In Europe, since they use the metric system, it is based on meters. The 20/20 equivalent is 6/6 because they use a 6-meter test distance. The second number is the smallest line of letters that a patient can read. In other words, 20/20 vision means that at a 20-foot test distance, the person can read the 20/20 line of letters. The technical definition of 20/20 is full of scientific jargon - concepts such as minutes of arc, subtended angles, and optotype size. If you’d like to read more of the technical details there is a well-written article with illustrations by Dr. John Ellman, you can find here. For the purposes of our discussion here I’ll try to explain it in less technical terms. “Normal” vision is somewhat arbitrarily set as 20/20 (some people can see better than that). Let’s say you have two people: Person A with 20/20 vision and Person B with 20/40 vision. The smallest line of letters that person B can see at 20 feet is the 20/40 line. Person A, with “normal” 20/20 vision, could stand 40 feet away from that same line and see it. There is somewhat of a linear relationship in that the 20/40 letters are twice the size of the 20/20 letters and someone with normal vision could see a 20/40 letter at twice the distance as the person with 20/40 vision. So how does this translate to a glasses prescription? Eye doctors can often estimate what your uncorrected VA will be based on your glasses prescription. This works mainly for near-sightedness. Essentially, every quarter step of increasing glasses prescription (i.e. -1.25 as compared to -1.50) means a person can see one less line on a VA chart. A prescription of - 1.25 works out to roughly 20/50 vision, -1.50 to 20/60 and so on. Anybody with an anatomically sound eyeball, meaning the absence of any kind of disease process, should generally be correctable to 20/20 with glasses or contact lenses. It is important to note, however, that rarely a person’s best corrected VA may be less than 20/20 with no noticeable signs of disease. Far-sightedness is more difficult to estimate because it is affected by a number of other factors, including one’s age and focusing ability. But that’s a topic for another article. So there you have it! Hopefully this has shed some light on what these measurements that we take actually mean, and it has allowed you to understand your eye health a little bit better. Article contributed by Dr. Jonathan Gerard