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New device combines perimetry and fundus imaging for customized exams
The MP-1 Microperimeter, with faster exam times, is achieving popularity in Europe as an alternative to earlier microperimetry systems.
PADOVA, Italy — A recent addition to retinal diagnostic technology offers a fast, convenient and highly personalized way to assess macular function, according to a surgeon who has become an expert in the technology.
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The MP-1 Microperimeter, manufactured by Nidek Technologies Srl, was developed in Italy and is beginning to increase in popularity throughout Europe. It was recently approved by the Food and Drug Administration for distribution in the United States.
The device’s main advantage over classic or automated perimetry lies in its high-speed image tracking software, according to Edoardo Midena, MD, of the University of Padova.
“The MP-1 works differently than what we are used to, in that it has a tracking system that allows the examiner to continuously check how (the patient’s) fixation has moved,” Dr. Midena told Ocular Surgery News.
“While fixation seemed to have had little importance in our past experience, we now know that good fixation can determine a patient’s ability to read correctly, for example,” he said.
The MP-1 provides a quantitative assessment of fixation by tracking fundus movements while the patient looks steadily at the fixation target, according to Nidek.
The autotracking system calculates x, y and rotational shifts relative to a reference frame and returns a map of the patient’s eye movements during the examination.
The MP-1 can also accurately map a scotoma by delineating the absolute or relative nonseeing areas within the visual field. This is accomplished by projecting a light stimulus onto the patient’s retina until it becomes visible to the patient. This is done with real-time control of the tested area by the examiner, who chooses the area to be tested.
In Dr. Midena’s experience, the tracking system has benefits that go beyond diagnosis. With the MP-1, he said he is able to monitor the evolution of a disease and the exact changes it effects on a patient’s vision over the long term, because follow-up examinations are automatically performed in previously examined areas.
“The parameter of fixation this machine gives you with software is important, not only for diagnosis or follow-up, but also for the visual rehabilitation of the patient,” he said. “Before initiating a program of rehabilitation, it is important to understand the fixation of each individual patient in order to personalize treatment and improve fixation, thus enabling the patient to read better or to see certain objects.”
The importance of fixation is further illustrated by cases in which the patient demonstrates good visual acuity but eccentric fixation.
“A patient may tell the doctor he cannot see very well, even with good visual acuity. This is because the patient’s fixation is becoming unstable, and then you see the development of scotoma,” he said.
Faster and more reliable
Another advantage of the MP-1 is its relative speed and convenience, according to Dr. Midena. Compared to previous systems, which require 15 to 20 minutes to check each eye, the MP-1 takes less than 5 minutes for the entire examination. This difference is especially important when dealing with age-related macular degeneration, he said.
“When you are dealing with elderly people, it can be difficult to maintain their attention for more than a few minutes, which means that in the past you often obtained unreliable results (from classic perimetry),” he said.
“The SLO is fantastic, but it is boring for the patient because of how long the procedure takes, so there is little reproducible or reliable data during the follow-up period,” he added.
The MP-1 is also capable of capturing color digital retinal images at the beginning and end of the examination. Infrared light is used for observation, and real-time, nonmydriatic retinal images are displayed on the monitor.
One complaint about conventional fundus imaging is that the black-and-white images can be difficult to decipher, Dr. Midena noted.
With the MP-1, the clinician obtains color photos overlayed with an image of an area of fixation and sensitivity of the retina, Dr. Midena explained.
Despite its high-tech capabilities, the MP-1 is less complicated than SLO technology and can be used by a technician, he said.
What the future holds
Dr. Midena said he envisions the MP-1 growing in popularity and becoming a standard fixture whenever there is a need for information on the macular function in patients with maculopathy.
For example, for a patient with a macular hole or pseudomacular hole, the MP-1 can help determine if surgery is warranted by examining the degree of the absolute scotoma or relative scotoma around the macular hole, he said.
According to Dr. Midena, the MP-1 is gaining ground in Italy and throughout Europe but is still a very new technology. In Italy, for example, it has only been available for about a year. It is now available in the United States.
Yet he said his department at the University of Padova often has patients referred there by other surgeons who do not have access to the technology to determine if a patient is a good candidate for surgery.
While the MP-1 is currently used exclusively to assess macular diseases, Dr. Midena said he would not be surprised if its use is extended in the future to other types of diseases. For example, it could be used for patients with early glaucoma to test for sensitivity around the papillary area, he said.
For Your Information:
- Edoardo Midena, MD, is a professor of ophthalmology and visual sciences at the University of Padova. He can be reached at Via Giustiniani, 2-35128 Padova, Italy; (39) 049-821-2121; fax: (39) 049-821-2129; e-mail: edoardo.midena@unipd.it. Dr. Midena has no direct financial interest in the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
- Nidek Technologies, manufacturer of the MP-1 Microperimeter, can be reached at 5500 West Friendly Ave., Greensboro, NC 27410; (336) 851-0225; fax: (336) 851-0917.