Which description best defines microperimetry?

Fundus-controlled perimetry that tracks eye movements Microperimetry measures retinal sensitivity at known fundus locations while tracking the eye, which corrects for the eccentric fixation that undermines standard perimetry in central scotomas.

Static automated perimetry assuming steady central fixation

Electrophysiological recording of focal macular cone responses

Dark-adaptation testing of rod recovery after bleaching

How does microperimetry keep each light stimulus on the intended retinal point during testing?

By infrared fundus tracking that moves stimuli with the retina An infrared camera images the fundus in real time and locks onto retinal landmarks, so the stimulus moves with the retina and stays on the intended tissue.

By requiring the patient to hold perfectly central fixation

By averaging thresholds across the whole test grid

By projecting stimuli onto a fixed bowl background

In microperimetry fixation analysis, what does the bivariate contour ellipse area describe?

The area containing most recorded fixation points The device records the fixation point throughout the test and reports its location, its stability and the bivariate contour ellipse area, the area that holds most fixation points.

The area of the densest scotoma on the map

The area of geographic atrophy on autofluorescence

The area of the foveal avascular zone

Locating a preferred retinal locus on microperimetry is chiefly useful for which clinical purpose?

Guiding low vision rehabilitation and visual aids Patients with central disease may fixate with a preferred retinal locus away from the fovea; mapping it shows the low vision team where to place visual aids and how to train fixation.

Calculating intraocular lens power before cataract surgery

Staging the severity of diabetic retinopathy

Selecting the interval between anti-VEGF injections

Which stimulus size and threshold strategy are typical for microperimetry testing?

Goldmann III with a 4-2 staircase strategy A typical microperimetry protocol uses a Goldmann III stimulus with a 4-2 staircase, on a grid such as a 10-2 pattern or custom points around a lesion.

Goldmann V with a SITA Fast strategy

Goldmann I with a full-threshold strategy

Goldmann III with suprathreshold screening only

Dark-adapted scotopic microperimetry adds most information over standard mesopic testing in which disease group?

Retinal diseases that affect the rods Mesopic testing is the standard microperimetry condition, while dark-adapted scotopic testing adds information in rod diseases.

Optic neuropathies such as glaucoma

Vitreomacular traction syndromes

Which step reduces the learning effect that distorts microperimetry results?

A short practice run before the actual test Microperimetry shows a learning effect, so patients should do a short practice run first; skipping it inflates the effect.

Testing the worse eye before the better eye

Switching to a larger Goldmann V stimulus

Shortening the grid to a single central point

In age-related macular degeneration, how does microperimetric sensitivity loss over drusen and atrophy compare with visual acuity?

It often exceeds what acuity suggests Sensitivity falls over drusen and in atrophic areas, and the functional loss often exceeds what acuity suggests, which is why microperimetry may detect change before acuity does.

It appears only after acuity has fallen

It closely mirrors the Snellen acuity line

It is confined to the fixation point

When should a change in microperimetry sensitivity in macular degeneration be counted as real progression?

When it exceeds the test-retest repeatability limits Test-retest variability is notable in microperimetry, so a change must exceed the repeatability limits before it counts as real change.

When any single test point falls by 1 dB

When visual acuity drops by one Snellen line

When fixation shifts to a new retinal locus

When a microperimetry sensitivity map is overlaid on OCT, loss of which retinal component predicts low sensitivity?

The outer retinal layers Outer retinal loss on OCT predicts low microperimetric sensitivity, so many centers report structure and function together and use the combined picture to explain symptoms.

Microperimetry: Mapping Retinal Sensitivity and Fixation

Microperimetry is fundus-controlled perimetry that measures retinal sensitivity at known locations while it tracks eye movements.

Standard perimetry assumes steady fixation, and patients with central scotomas often fixate eccentrically. Microperimetry corrects for this problem, and it links function to structure on OCT and fundus images.

How Microperimetry Works

The device images the fundus in real time with an infrared camera and locks onto retinal landmarks. It then presents light stimuli at chosen points, and the patient presses a button when the light is seen.

Tracking moves the stimulus with the retina, so each test point stays on the intended tissue. Results appear as a map of sensitivity in decibels, overlaid on the fundus image (see fundus autofluorescence imaging).

Fixation Analysis in Microperimetry

The device also records the position of the fixation point during the test. It reports the fixation location, stability, and the area that contains most fixation points, called the bivariate contour ellipse area.

Patients with central disease may use a preferred retinal locus away from the fovea, and the map shows where it lies. Fixation analysis helps in low vision rehabilitation, since it shows where to place visual aids.

Test your knowledge 10 questions from this article

Test Protocols

Examiners choose a grid, such as a 10-2 pattern, or custom points around a lesion. Typical stimulus size is Goldmann III and the strategy is a 4-2 staircase, while mesopic testing is standard and dark-adapted scotopic testing adds information in rod diseases. Because a learning effect occurs, patients should do a short practice run first.

Clinical Uses of Microperimetry

Age-related macular degeneration, including geographic atrophy and drusen
Stargardt disease and other macular dystrophies
Retinitis pigmentosa and cone-rod dystrophies
Macular hole, epiretinal membrane, and diabetic maculopathy

In trials, microperimetry gives a functional end point that may detect change before acuity does (see Stargardt disease).

Microperimetry in Age-Related Macular Degeneration

Sensitivity falls over drusen and in areas of atrophy, and the loss often exceeds what acuity suggests. Markowitz and Reyes reviewed the evidence and found that microperimetry correlates with structural change. Test-retest variability is notable, so changes need to exceed the repeatability limits to count (see geographic atrophy treatment).

Limits of Microperimetry

Long test time and fatigue
Learning effect and variable cooperation
Limited dynamic range in some devices
Device-specific normal values

Therefore, interpret results with caution, and repeat the test when findings are unexpected.

An Example Case

A 72-year-old woman with geographic atrophy in both eyes has acuity of 20/60 and reads slowly. Microperimetry shows dense scotomas in the central 4 degrees and a preferred retinal locus above the atrophic area.

The low vision team uses this map to train her to look slightly below the target, and her reading speed improves. Repeated tests every six months show stable sensitivity over several visits, and the map guides her follow-up.

Microperimetry: Mapping Retinal Sensitivity and Fixation

Questions Patients Ask

Patients ask why they need another visual field test, and the answer is that this test shows exactly where the retina sees. They also ask whether the test is tiring, and the session lasts about ten minutes per eye, so offer short breaks and a quiet room because attention affects results.

Pitfalls to Avoid

Testing before dilation or in poor lighting without noting it
Skipping the practice run, which inflates the learning effect
Comparing results between devices with different stimulus ranges
Reading small changes in sensitivity as real change without checking repeatability

Looking Ahead

Faster algorithms and scotopic testing are entering routine devices, and researchers also use microperimetry as an outcome in trials of geographic atrophy and gene therapy. Therefore, expect broader use as normative data grow.

Practical Points

Record the device, the grid, and the stimulus settings in the chart, then compare each result with the previous one using the same protocol. Also store the fundus image with the map, so that the findings link to structure.

Combining Microperimetry With OCT

Overlay the sensitivity map on the OCT to see which layers match each scotoma. Because outer retinal loss predicts low sensitivity, many centers report both findings together. Then use the combined picture to explain symptoms to the patient, and also record the fixation pattern, since it guides rehabilitation.

Training and Staffing

Train a technician to run the test, and use a standard script for instructions. Because results depend on how the patient understands the task, check comprehension before starting, and then audit repeatability from time to time.

References

Markowitz SN, Reyes SV. Microperimetry and clinical practice: an evidence-based review. Can J Ophthalmol. 2013;48:350-357.
Midena E, Radin PP, Pilotto E, et al. Fixation pattern and macular sensitivity in eyes with subfoveal choroidal neovascularization secondary to age-related macular degeneration: a microperimetry study. Semin Ophthalmol. 2004;19:55-61.
Wu Z, Ayton LN, Guymer RH, Luu CD. Intrasession test-retest variability of microperimetry in age-related macular degeneration. Invest Ophthalmol Vis Sci. 2013;54:7378-7385.
American Academy of Ophthalmology. Basic and Clinical Science Course, Section 12: Retina and Vitreous. AAO; current edition.

Test yourself

A few questions straight from this article.

1 / 10 0 correct

Which description best defines microperimetry?
Microperimetry measures retinal sensitivity at known fundus locations while tracking the eye, which corrects for the eccentric fixation that undermines standard perimetry in central scotomas.
How does microperimetry keep each light stimulus on the intended retinal point during testing?
An infrared camera images the fundus in real time and locks onto retinal landmarks, so the stimulus moves with the retina and stays on the intended tissue.
In microperimetry fixation analysis, what does the bivariate contour ellipse area describe?
The device records the fixation point throughout the test and reports its location, its stability and the bivariate contour ellipse area, the area that holds most fixation points.
Locating a preferred retinal locus on microperimetry is chiefly useful for which clinical purpose?
Patients with central disease may fixate with a preferred retinal locus away from the fovea; mapping it shows the low vision team where to place visual aids and how to train fixation.
Which stimulus size and threshold strategy are typical for microperimetry testing?
A typical microperimetry protocol uses a Goldmann III stimulus with a 4-2 staircase, on a grid such as a 10-2 pattern or custom points around a lesion.
Dark-adapted scotopic microperimetry adds most information over standard mesopic testing in which disease group?
Mesopic testing is the standard microperimetry condition, while dark-adapted scotopic testing adds information in rod diseases.
Which step reduces the learning effect that distorts microperimetry results?
Microperimetry shows a learning effect, so patients should do a short practice run first; skipping it inflates the effect.
In age-related macular degeneration, how does microperimetric sensitivity loss over drusen and atrophy compare with visual acuity?
Sensitivity falls over drusen and in atrophic areas, and the functional loss often exceeds what acuity suggests, which is why microperimetry may detect change before acuity does.
When should a change in microperimetry sensitivity in macular degeneration be counted as real progression?
Test-retest variability is notable in microperimetry, so a change must exceed the repeatability limits before it counts as real change.
When a microperimetry sensitivity map is overlaid on OCT, loss of which retinal component predicts low sensitivity?
Outer retinal loss on OCT predicts low microperimetric sensitivity, so many centers report structure and function together and use the combined picture to explain symptoms.

Ahmed Ophthalmologist

Writes and reviews the clinical articles on Educate. Every post is checked against peer-reviewed sources before it goes live.