Macular degeneration is diagnosed through a combination of a dilated eye exam, retinal imaging, and sometimes at-home vision tests. The process typically starts with your eye doctor looking at the back of your eye for yellowish deposits called drusen, which are the hallmark early sign of the disease. From there, more advanced imaging can determine whether you have the dry or wet form and how far it has progressed.
What Happens During a Dilated Eye Exam
The first and most important step is a dilated eye exam. Your doctor places drops in your eyes that widen your pupils, giving them a clear view of the retina at the back of your eye. The drops take about 15 to 30 minutes to fully work, and your vision will stay blurry for a few hours afterward, so you’ll want someone to drive you home.
Once your pupils are dilated, the doctor uses a slit lamp, a microscope with a focused beam of light, to examine your retina in detail. You’ll rest your chin on a support and press your forehead against a strap while they look through the lens. They’re searching for drusen (small fatty deposits under the retina), pigment changes, thinning of retinal tissue, or any signs of abnormal blood vessel growth. Before the detailed exam, they may also check your peripheral vision by holding up fingers in different positions and asking you to track their hand.
Both optometrists and ophthalmologists can perform this exam and spot macular degeneration. If they detect it, or if you suspect something is wrong, you can be referred to a retina specialist for further evaluation and imaging.
The Amsler Grid: A Simple Screening Tool
An Amsler grid is a square grid of evenly spaced lines with a dot in the center. It’s one of the simplest tools for detecting changes in your central vision, and your doctor may use it during an office visit or give you one to use at home for ongoing monitoring.
To use it, hold the grid at normal reading distance (about 12 to 15 inches from your face) while wearing your usual glasses or contacts. Cover one eye and focus on the center dot without moving your gaze. While staring at the dot, check whether all four corners of the grid are visible, all lines appear perfectly straight, no areas look dark or blank, and no lines appear blurred or wavy. Then repeat with the other eye.
If any lines look wavy, broken, or missing, that’s a sign the macula may be distorted. This doesn’t confirm a diagnosis on its own, but it’s a useful early warning, especially for people already diagnosed with dry macular degeneration who need to watch for progression to the wet form.
How OCT Reveals Retinal Damage
Optical coherence tomography, or OCT, is the most commonly used advanced imaging test for macular degeneration. It’s painless, takes only a few minutes, and requires no injections. The machine scans your eye with light to create detailed cross-sectional images of the retina, almost like a microscopic ultrasound.
These images let your doctor measure the thickness of individual retinal layers and spot abnormalities that aren’t visible during a standard eye exam. In dry macular degeneration, OCT can identify drusen deposits sitting beneath the retinal pigment layer, along with areas where the retina is thinning. This thinning indicates geographic atrophy, an advanced form of dry macular degeneration where retinal cells have died. In wet macular degeneration, OCT can detect fluid buildup under or within the retina, a telltale sign that abnormal blood vessels are leaking.
Because OCT is so quick and noninvasive, doctors also use it to track disease progression over time. Comparing scans from visit to visit shows whether drusen are growing, fluid is accumulating, or retinal layers are thinning further.
Fundus Photography and Autofluorescence
Fundus photography uses a specialized camera to take high-resolution pictures of the retina through your dilated pupil. These images create a detailed record of what the back of your eye looks like, capturing drusen, pigment changes, and areas of damage. They serve as a baseline so your doctor can compare future photos and track whether the disease is stable or worsening.
Fundus autofluorescence (FAF) is a variation that detects damaged or dying cells in the retinal pigment layer. Healthy cells naturally emit a faint glow when hit with a specific wavelength of light, while damaged or dead cells don’t. The resulting image highlights areas of geographic atrophy as dark patches where cell loss has occurred. This makes FAF particularly useful for measuring how quickly advanced dry macular degeneration is spreading.
Fluorescein Angiography for Wet AMD
If your doctor suspects the wet form of macular degeneration, they may order a fluorescein angiography. This test involves injecting a fluorescent dye into a vein in your arm, then photographing your retina as the dye travels through the blood vessels in the back of your eye. The whole process takes about 10 to 15 minutes.
In a healthy eye, the dye flows neatly through normal blood vessels. In wet macular degeneration, abnormal blood vessels have grown beneath the retina, and these vessels are fragile and leaky. The dye escapes from them, creating bright fluorescent patches on the images. This leakage pattern confirms the presence of wet AMD and shows exactly where the abnormal vessels are located, which helps guide treatment decisions.
Some patients feel mildly nauseous from the dye, and your skin may appear slightly yellow for a few hours afterward. Your urine will also turn bright orange for a day or two as the dye clears your system. These effects are harmless.
Telling Wet and Dry AMD Apart
The distinction between dry and wet macular degeneration matters because the two forms behave differently and require different management. Dry AMD, which accounts for about 80 to 90 percent of cases, involves gradual thinning of the macula and accumulation of drusen. It progresses slowly over years. Wet AMD occurs when new, abnormal blood vessels grow under the retina and leak fluid or blood, causing faster and more severe vision loss.
Your doctor uses the combination of tests above to distinguish between them. OCT is often the first clue: fluid under or within the retina strongly suggests wet AMD, while thinning without fluid points to dry. Fluorescein angiography then confirms wet AMD by directly showing the leaking vessels. In some cases, a related test called indocyanine green angiography uses a different dye that’s better at imaging blood vessels beneath the retinal pigment layer, which helps rule out conditions that can mimic wet AMD.
What the Stages Mean
Macular degeneration is classified into stages based on what your doctor sees on imaging, primarily the size and number of drusen.
- Early AMD: Small to medium drusen (roughly the width of a human hair or smaller) are present, but there’s usually no vision loss. Most people at this stage don’t know they have it.
- Intermediate AMD: Drusen are larger, and there may be pigment changes in the retina. Some people begin to notice mild blurriness or difficulty reading in dim light, though many still have no symptoms.
- Late AMD: Either geographic atrophy (advanced dry) or wet AMD is present. Vision loss in the center of your visual field becomes noticeable and can progress to significant impairment.
Staging matters because it determines how frequently you need monitoring and whether treatment is recommended. Early AMD may only require annual exams and home Amsler grid checks, while intermediate and late stages call for more frequent visits and, in the case of wet AMD, active treatment to slow further vision loss.