Microperimetry: Mapping Your Central Vision Health
Understanding Microperimetry
Microperimetry is a non-invasive test that measures how sensitive different points of your macula are to light. During the test, small lights of varying brightness are projected onto specific areas of your retina. Your responses to these lights are recorded and used to build a color-coded map of your central visual function.
What makes microperimetry unique is that it combines two tasks in one sitting. It tests your visual sensitivity point by point while capturing a live image of your retina using infrared scanning laser ophthalmoscopy (SLO). This means each sensitivity measurement is linked to the exact spot on your retina where it was taken.
Traditional visual field tests, sometimes called perimetry, measure your overall field of vision. They do not show a direct picture of your retina at the same time. If your eye moves during a standard test, results can be less accurate. Microperimetry solves this problem with built-in eye-tracking technology. The device follows your eye movements in real time and adjusts automatically.
This eye-tracking feature is especially important for people who have difficulty holding their gaze steady. Patients with macular disease often lose the ability to look straight ahead. Instead, they use a different part of the retina for viewing. This alternate viewing spot is called the preferred retinal locus (PRL). Microperimetry can identify and map the PRL.
Microperimetry combines three important features into one examination:
- Light sensitivity testing: Small lights are projected onto your retina at many points to measure how well each area detects light. Results are recorded in decibels (dB).
- Live retinal imaging: An infrared SLO fundus image is captured in real time so each test point is matched to a specific retinal location.
- Eye tracking: The device continuously monitors and corrects for eye movement, ensuring accurate and repeatable results.
Who Benefits from Microperimetry
Age-related macular degeneration (AMD) is one of the most common reasons a retina specialist may recommend microperimetry. Patients with early, intermediate, or advanced AMD can benefit from this test. Geographic atrophy (GA), an advanced form of dry AMD, affects approximately 5 million people worldwide (BMC Ophthalmology, 2019). Microperimetry helps track how GA expands and affects visual function over time.
For patients receiving treatment for geographic atrophy, microperimetry serves as an important way to measure whether therapy is preserving visual function. It can detect subtle changes in retinal sensitivity that other tests may miss.
People with diabetic retinopathy or diabetic macular edema can develop areas of reduced sensitivity in their central vision. Standard visual acuity testing may still show acceptable results even when functional vision has declined. Microperimetry reveals these hidden areas of damage. This helps the retina specialist decide when and how to treat.
Inherited retinal conditions such as Stargardt disease, cone-rod dystrophies, and macular forms of retinitis pigmentosa cause progressive damage to the macula. Microperimetry provides detailed information about how these diseases affect central vision over time. This helps guide treatment decisions and track disease progression more accurately than visual acuity alone.
Certain medications can cause damage to the retina as a side effect. In drug-induced retinopathies, visual field changes detected by microperimetry often appear before structural changes are visible on OCT or fundus photography. This makes the test a vital tool for early detection.
Signs and Symptoms That May Prompt Testing
A retina specialist may recommend microperimetry when a patient reports difficulty with tasks that depend on central vision. These include reading, recognizing faces, and seeing fine details. Sometimes patients describe a blurry or dark spot near the center of their vision, even when measured visual acuity seems adequate.
One of the most valuable uses of microperimetry is when standard eye chart results do not match daily experience. A person may read several lines on a chart yet struggle to read a book or see a clock. Microperimetry can reveal localized areas of reduced sensitivity surrounding the point of fixation. This explains why function is poor despite reasonable acuity scores.
For patients already diagnosed with a macular disease, microperimetry may be ordered at regular intervals. The test can detect worsening sensitivity before a patient notices new symptoms. Early detection of functional decline allows the retina specialist to adjust the treatment plan sooner.
Diagnosis and Testing: What Microperimetry Reveals
After the test, results are displayed as a color-coded map overlaid on the image of your retina. Each color represents a different level of light sensitivity:
- Green indicates normal or near-normal sensitivity.
- Yellow to orange indicates reduced sensitivity, also called relative scotomas.
- Red or black indicates deep blind spots with minimal or no light perception, known as absolute scotomas.
Microperimetry also measures how steadily you fixate, or hold your gaze, during the test. Stable fixation is a sign of healthier macular function. Unstable fixation may indicate more advanced disease. If the fovea (the very center of the macula) is damaged, the test identifies the preferred retinal locus where the eye has shifted its focus.
Because the sensitivity map is registered directly onto a live fundus image, the retina specialist can see exactly which structural features correspond to areas of vision loss. For example, an area of geographic atrophy visible on the retinal image can be matched to the precise zone of reduced sensitivity on the map. This structure-function correlation is one of the greatest strengths of microperimetry.
Two FDA-cleared microperimetry devices are commonly used in retina practices today. The MAIA (Macular Integrity Assessment), developed by CenterVue and now part of iCare, integrates an automated perimeter and ophthalmoscope. It captures retinal images over a 36-degree field of view under infrared illumination.
The MP-3, manufactured by NIDEK, offers similar capabilities. Both devices record eye movements, measure light sensitivity at multiple macular locations, and provide quantitative data on macular function.
Treatment Connections: How Microperimetry Guides Care
Microperimetry has become a key measurement tool in clinical trials for geographic atrophy treatments. Syfovre (pegcetacoplan), a complement inhibitor approved for geographic atrophy, demonstrated positive results in microperimetry endpoints. Data from long-term studies showed that patients treated for 36 months scored better on prespecified microperimetry endpoints than those treated for only 12 months (Modern Retina, 2024).
This was reported as the first time a treatment for geographic atrophy showed a positive visual function benefit on a prespecified endpoint (Modern Retina, 2024). Research also showed approximately a 35 percent risk reduction in central vision loss among patients who received early treatment compared to those who started later (Modern Retina, 2024). Microperimetry was one of the tools used to measure this benefit.
For patients with wet AMD receiving anti-VEGF injections (medications that block abnormal blood vessel growth and leakage), microperimetry can help assess whether treatment is preserving or improving retinal function. Common anti-VEGF medications for wet AMD include Eylea (aflibercept), Lucentis (ranibizumab), Vabysmo (faricimab), and Avastin (bevacizumab), which is used off-label for eye conditions. Visual acuity may remain stable while sensitivity at certain retinal points changes. Microperimetry captures these differences. It is important to note that anti-VEGF injections are used specifically for wet AMD and are not a treatment for dry AMD.
Patients with diabetic macular edema (DME) also benefit from microperimetry monitoring during anti-VEGF treatment. DME is a separate condition from wet AMD and involves fluid leakage in the macula caused by diabetes. Microperimetry can reveal improvements or declines in macular sensitivity that visual acuity testing alone may not detect. This information helps the retina specialist fine-tune treatment timing and frequency.
Because the eye-tracking system ensures the same retinal points are tested each visit, microperimetry provides reliable follow-up data. A retina specialist can compare sensitivity maps from different dates to see whether a condition is stable, improving, or getting worse. This is particularly useful for slowly progressive diseases like geographic atrophy, Stargardt disease, and other inherited retinal conditions.
What to Expect During Microperimetry
Microperimetry does not usually require dilation of the pupils. Your retina specialist may dilate your eyes depending on the clinical situation. No special preparation is needed. The test is performed in a dimly lit room. You will be seated comfortably in front of the device with your chin resting on a support.
You will look into the device and see small lights appear one at a time at different locations. Each time you see a light, you press a button. The lights vary in brightness. Some will be easy to see and others may be very faint or invisible.
The test typically takes 10 to 15 minutes per eye. It is painless and non-invasive. The eye tracker follows your gaze, so you do not need to worry about keeping your eye perfectly still.
Results are available immediately. Your retina specialist will review the color-coded sensitivity map and fixation data with you. No recovery time is needed, and you can resume normal activities right away. If your eyes were dilated for additional testing, you may experience temporary light sensitivity and blurred vision.
Living with a Macular Condition
Microperimetry results give you and your retina specialist a clear picture of which parts of your central vision are working well. They also show which areas have been affected by disease. Understanding your map can help explain daily challenges such as difficulty reading certain sized text or noticing gaps in your central vision.
For patients with significant central vision loss, microperimetry helps identify the preferred retinal locus. This information is valuable for low vision rehabilitation specialists. They can train patients to use their remaining vision more effectively. Knowing exactly where functional vision is preserved allows for more targeted rehabilitation strategies.
Macular diseases often progress gradually. Regular microperimetry testing, combined with other imaging such as OCT and fundus photography, gives the most complete picture of your eye health. Following the monitoring schedule recommended by your retina specialist helps ensure that any changes are caught early.
When to See a Retina Specialist
If you notice new blurriness, distortion, or a dark spot in your central vision, see a retina specialist for evaluation. Microperimetry may be recommended as part of a thorough assessment to determine the cause and extent of your vision changes.
Certain symptoms require urgent care. See a retina specialist or go to the emergency room immediately if you experience a sudden increase in floaters, flashes of light, a curtain or shadow across your vision, or sudden vision loss in one eye. These symptoms may indicate a retinal emergency such as a retinal detachment.
If you have been diagnosed with AMD, diabetic eye disease, an inherited retinal disease, or another macular condition, keep all scheduled appointments. Your retina specialist will determine how often microperimetry and other tests should be repeated based on your specific situation and treatment plan.
Questions and Answers
Microperimetry and standard visual field testing both measure sensitivity to light, but they work differently. Standard perimetry does not capture a simultaneous image of the retina. Results cannot be precisely matched to specific retinal structures. Microperimetry uses live retinal imaging and eye tracking to link each sensitivity measurement to an exact point on your retina. This makes it especially useful for evaluating macular diseases.
Microperimetry is completely non-invasive. There are no injections, no contact with your eye, and no discomfort. You simply look into the device and press a button when you see a light. The test typically takes 10 to 15 minutes per eye. Most patients find it straightforward and comfortable.
Yes. One of the key advantages of microperimetry is its ability to detect reduced retinal sensitivity before a patient notices changes in daily vision. In conditions such as early AMD, geographic atrophy, and drug-induced retinopathies, subtle functional deficits may appear on microperimetry before they show up on standard imaging. This early detection can lead to earlier intervention.
The frequency depends on your specific condition and treatment plan. Some patients may have microperimetry performed every few months, while others may be tested once or twice a year. Your retina specialist will recommend a schedule based on the type and stage of your eye condition and how quickly changes are expected to occur.
Microperimetry is typically one part of a comprehensive evaluation. It is often used alongside optical coherence tomography (OCT), fundus photography, fluorescein angiography, and standard visual acuity testing. Together, these tests provide both structural and functional information about your retina. Microperimetry adds the unique ability to show how well specific areas of the macula are working.