As the owner of a busy ophthalmology clinic, I found the need for a device that would allow me to fully test and educate patients on how changes to their macula can impact their vision. For this reason, I recently decided to install NIDEK's MP-3 Microperimeter in my practice.
What It Is
In its most basic sense, the NIDEK MP-3 Microperimeter is an automated perimetry machine. Although microperimetry is not a new technology, what makes this device different from others on the market is that it will simultaneously provide autotracking of the fundus for constant tracking of the patient's fixation.
By constantly verifying the stimulus point is always at the same point on the retinal surface, the device allows for extremely accurate perimetry of either small or large areas of the retina. Also, fully automated fundus tracking means no manual maintenance for the operator, making the test easier and quicker for busy clinical practices.
Because the device is capable of measuring perimetry within less than one degree of the visual field, it allows for measurement of just macular function. This can be very important in conditions such as dry age-related macular degeneration where the patient may have drusen and pigment epithelial detachment, but the retina looks relatively intact. This test allows practitioners to know if the drusen or pigment epithelial detachment is having an impact on macular function — this is the first test I've seen that makes it practical to measure that function.
Example scans from the NIDEK MP-3 Microperimeter. Top row, from left -- excessive myopia and epi-retinal membrane. Bottom row, from from left -- age-related macular degeneration (geographic atrophy) and retinal angiomatous proliferation.
How It Works
The MP-3 Microperimeter is a fully non-invasive test, and is very easy to use both for the operator and the patient. The patient places their head in the chin rest and the machine automatically aligns with their pupil. The machine then automatically obtains an infrared image of the fundus used for tracking during the perimetry exam, and at the end of the exam it automatically captures a color fundus image to align with the microperimetry.
Just like any automated perimetry test, the patient does have to push a trigger button whenever they see a stimulus. However, because of the automatic retinal tracking the stimulus is always going to be at the same place on the fundus, allowing for a much greater degree of accuracy. With this particular test, there is really never any fixation error to the perimetry testing because the machine is always accounting for the change in fixation and consistently keeping the stimulus at the same point on the retina.
In addition, the MP-3 Microperimeter also can be used to take fundus photographs or administer a standalone fixation test.
The other benefit to this microperimeter is its customization options. For perimetry testing, the user can set and save the testing points in any pattern they wish, making the perimetry fully customizable.
Education, Follow-Up & Treatment Benefits
Over the past few months of using the MP-3 Microperimeter in my practice, I have found it to be very helpful in educating patients about how conditions like age-related macular degeneration impact their vision. The device uses NIDEK's NAVIS-EX image filing software to pull up images as soon as they are taken at any exam station, so right away I can show patients their test results.
The microperimeter creates a color map of the decibels of attenuation, giving patients a visual way to easily understand which areas may, for example, have a micro-scotoma or mild to moderate decrease in retinal sensitivity.
This became very helpful with one particular patient who came in with an eye trauma. Although their exam findings were basically normal and nothing significant showed on the OCT, the patient complained about a puzzle-piece shaped spot in their vision. However, the microperimetry test on the MP-3 resulted in a color map showing decreased sensitivity in the same puzzle-piece shape the patient had described, validating the patient's concerns and providing me with the information I needed to diagnose their condition.
Another benefit to using the MP-3 Microperimeter has been in patient follow-up. Whenever a patient comes in for a follow-up exam, the device will use their previous exam to auto-align the stimulus points in the same exact places. It will also provide me with a side-by-side of any change in sensitivity at each testing point. This allows me to test the effect on macular function over time, and makes it very quick and easy to see how function may have changed.
I also have had a few cases where findings through the MP-3 made an impact on treatment decisions. For example, I had a patient with a long history of diabetes and age-related macular degeneration who was unable to undergo fluorescein angiography testing due to an allergy., In one area of the macula, the patient had retinal hemorrhage and edemas which may have been consistent with either exudative macular degeneration or diabetic retinopathy. Microperimetry testing showed a very discreet micro-scotoma near the macula, suggesting more a diagnosis of exudative macular degeneration that was useful in planning treatment.
New Insight On Macular Function
The MP-3 Microperimeter gives providers unique functional information about a patient’s macula and retina, and it is proving to be very useful in patients who have either decreased visual acuity or visual distortions that aren’t explained by any anatomic findings.
In general, I’ve been very happy with the new information the machine has been providing. It really gives a new insight on macular function that I never had before with any other device.
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