Frey Perimeter AP-600

Patient-Focused – Enhanced Patient Comfort

Visual field assessment is a joint task between the physician and the patient. Visual field assessment, also known as perimetry, is a team effort. A patient who is well supported and provided with the greatest possible comfort improves the reliability of visual field evaluation. This increased reliability translates into greater accuracy and effectiveness in diagnosis and clinical management. In turn, this improves outcomes and patient satisfaction throughout their care journey, which may extend over decades. Frey has achieved enhanced patient comfort through a chinrest design focused on comfort and stability. The patient’s head remains supported throughout the entire examination. The AP-600 features improved patient ventilation, reducing stress and increasing comfort.

The AP-600 Perimeter features an integrated PC along with an integrated touchscreen monitor that controls test execution and device operation, as well as a patient response button.

Accurate Results

The stimulator bowl provides a high density of concentric points. Enhanced stimulus control is combined with automated eye tracking, enabling a repeatable and accurate examination of the patient’s visual field loss.

Fast Test Times

Efficient tests are reliably performed with screening and fast threshold detection strategies, as well as enhanced fixation methods. Patients with advanced visual field loss are supported by pattern calibration methods and neurological testing.

During the test, reliability is monitored based on a selected strategy and parameters. Points are evaluated in random order, and the area corresponding to each test point is highlighted in green throughout the entire exposure. Points that have not yet been evaluated are marked in gray. The test process consists of examining the brightness of each cell; if there is no response to the stimulus, the cell description changes to red. A positive response is indicated by the color green. Completed test points are identified with a blue label. In addition to the standard test point exposures, the program runs special cycles that include false positive control, false negative control, fluctuation control, and blind spot control using Heijl-Krakau fixation. Information about the execution of these special cycles is displayed in the upper left corner of the test field area. The program also offers users the flexibility to manually adjust the test levels of points during the evaluation. It allows previously examined points to be re-evaluated if necessary.

If one of the static tests is selected, the static test screen will be displayed, containing:

1 – A test field with the points to be evaluated marked: A value in decibels is written at each point, indicating the brightness of the point being evaluated at that moment in the test. Points that have already been evaluated are colored blue, while points currently being evaluated are colored green, red, or black. A point whose evaluation has not yet begun is colored gray. Green indicates that the patient saw the point at the last evaluated brightness, while red indicates that the point was not seen. Black indicates that the patient’s response was abnormal (too fast or too slow, i.e., outside the test cycle), and the evaluation of the point will be repeated.
2 – Chin and forehead rest control buttons: These buttons are used to correctly adjust the patient’s position. The patient’s eye should be positioned at the center of the video preview window, although it does not need to be perfectly centered.
3 – Panel with patient data and test parameters: The panel contains information about the patient being evaluated and the test parameters (name, false positive and negative errors, fixation loss).
4 – Panel with video camera view of the patient’s eye: The panel displays the video camera image of the patient’s eye. For the correct functioning of digital eye tracking and test execution, it is important that the patient’s pupil be at the center of the image (a perfectly centered position is not required). However, it is far more important that the patient focus on observing the fixation point. The software calculates the eye position based on the digital analysis of an image containing the reflections of infrared diodes on the eye (two white dots within the pupil).

5 – Fixation Bar: The bar represents the fixation level over time. An instant fixation indicator is located on the left side of the bar. This bar can display three possible colors: BLACK, when the fixation level cannot be determined (eye closed, etc.) / RED, when fixation loss is too great / GREEN, when the fixation level is correct.
6 – Comments Field: Allows a comment to be added during test execution. The comment will be visible in the study results.
7 – Time Parameters Panel and Adaptation Switch:
Adaptive: Initiates automatic control of time parameters. The program estimates the patient’s reaction speed times and adjusts them to reduce the maximum test duration, ensuring that the reliability of the result is not compromised.
Exposure Time: The duration of stimulus illumination.
Response Time: The time the perimeter waits for the patient’s response after the stimulus turns off.
Wait: A parameter that specifies the time between two consecutive test cycles. It is counted from the end of the Response Time. Once this time has elapsed, the next test cycle will begin, meaning the next point will be illuminated.
Fluctuation: A random time interval between 0 and the set value by which the Wait time is increased.
8 – Test Start Button.
9 – Demo Start Button: A button for demonstration mode. It allows the patient to observe and understand the principles and process of the examination.
10 – Remap Blind Spot Button: Allows repositioning of the blind spot points. This function is only available in Heijl-Krakau mode (blind spot monitoring).
11 – Pause/Continue Button: Press this button to temporarily interrupt the test.
12 – Close Button: Allows the evaluation to be ended at any time and returns to the main program window.

Test Results Display

You can view the results of a test either from the main screen (by clicking the Test Results button) or from the patient data management (described in the section titled “Patient Data Management”). In the first case, you will see a list of patients, and selecting a patient record will open a list of all available examinations.

Static Test Results

La static test results screen provides the following information and functions described below:
1 – Test Parameters Panel: Displays the run parameters and run indices.
2 – Description: The editor allows you to enter a description.
3 – Results Display Panel: The panel presents the visual field examination result in various graphical or numerical forms.
4 – Display Mode Selection Box: Allows you to choose a presentation mode for the study results.
5 – Print Button: Allows you to print the test using one of three standard formats for static tests: Standard HFA 7 in 1 Standard Single Field
6 – Export Button: Allows you to export data in one of the selected formats: PDF, JPG/PNG, DICOM
7 – Next/Previous Run Buttons: These buttons allow you to navigate to the previous or next chronological study without closing the results window or manually selecting a study from the list.

Static test results presentation

dB Map

AN Map

Test parameters determined from the test results

Fixation Loss: The parameter is measured in two ways: using the Heijl-Krakau blind spot stimulation method or through a digital camera and eye position analysis. With the first method, fixation is verified randomly between standard measurement cycles. The second method continuously monitors position, providing information on fixation during the measurement of each visual field point.

False Positive Error: This error indicates patient responses to stimuli that were not actually presented. Periodically during measurement, the program runs an empty cycle in which no point is illuminated and checks whether the patient presses the button. The most common cause of this error is the patient pressing the button rhythmically or not fully understanding the test procedure.

False Negative Error: This error occurs when the patient does not respond to a stimulus that should be visible. This error is specifically evaluated at points where the visual threshold was previously determined during the test. In this case, the point is evaluated at a brightness 6 dB above the determined threshold.

Fluctuation: Defines the variability of designated brightness levels by repeating the test at four points whose brightness has already been determined. The four points are selected randomly, with one point chosen from each quadrant and located no more than 22˚ from the center. The fluctuation test begins after all cells within a field of up to 22˚ from the center have been evaluated. The fluctuation value increases as the sensitivity difference between the same evaluated points becomes greater.

Tested – Number of stimulus presentations: This parameter specifies the number of stimulus presentations in relation to the number of test fields.

Sensitivity level at the 1˚ and 3˚ circle – 3-degree level: The sensitivity level determined by the two circles closest to the center, namely the one-degree and three-degree circles.

Slope – Theoretical slope of the Hill of Vision: Specifies the expected slope of the Hill of Vision. The slope is expressed in decibels per 10 degrees.

Zero Level: The most frequent decibel value in the test result.

Mean: The mean value expressed in decibels and calculated from all evaluated visual field points. For fields where the patient could not see, marked with an X, a value of -1 dB is used to calculate the mean.

PD Pattern Defect: Determined from the projected Hill of Vision graph.

Mean Deviation MD: The average of all deviations formed by subtracting the values of corresponding points in the test result from the age-adjusted norm.

GHT – Glaucomatous Zonal Comparison: A parameter that compares five zones in the upper and lower halves of the field. These zones are located in areas where glaucomatous defects occur most frequently. The compared zones are placed symmetrically in the upper and lower parts of the field. Each zone in the upper part corresponds to an analogous zone in the lower part. The zones cover an area of up to 30 degrees from the center. The one-degree circle and points near the blind spot are excluded from the comparison areas.

During the kinetic test, a stimulus is presented to the patient near the outer edge of the visual field for 1 second. If the patient does not perceive the stimulus within 1 second, it begins to move toward the center of the field. When the patient perceives the stimulus, they must press a button. The perimeter repeats this stimulus movement along consecutive, randomly selected meridians. For the operator’s convenience, the stimulus is also displayed on the test screen as a circle of the appropriate color and size. The graphical representation of the test result is an isopter, which is a line connecting the points located on consecutive meridians where the patient perceived the stimulus. Within a given isopter, multiple meridians can be evaluated, separated by an angular density set by the examiner. Up to 8 isopters can be evaluated within a single kinetic test. If one of the kinetic tests is selected, the test screen will be displayed, containing:

1 – Test field
2 – Chin and forehead rest control buttons: These buttons are used to correctly adjust the patient’s position. The patient’s eye should be positioned at the center of the video preview window, although it does not need to be perfectly centered.
3 – Patient data and test parameters panel: The panel contains information about the test patient and the test parameters (name, false positive and negative errors, fixation loss).
4 – Patient eye video camera view panel: The panel displays a video camera image of the patient’s eye. For the correct operation of digital eye tracking and test execution, it is important that the patient’s pupil be centered in the image (an ideal central position is not required). However, it is far more important that the patient focus on observing the fixation point. The software calculates the eye position based on digital analysis of an image containing the infrared diode reflections on the eye (two white dots within the pupil).
5 – Fixation bar: The bar represents the fixation level over time. An instantaneous fixation indicator is located on the left side of the bar. This bar can take three possible colors: BLACK, when the fixation level cannot be determined (eye closed, etc.) / RED when fixation loss is too great / GREEN at the correct fixation level.
6 – Comments field: Allows a comment to be added during test execution. The comment will be visible in the study results.

7 – Kinetic Test Parameter Field:
Number of isopters: up to 8 isopters can be selected. A different range of parameters can be configured for each isopter. Isopters are labeled with letters (A through H). By pressing the key corresponding to a given isopter, the set of parameters that characterize it can be accessed.
Meridian angle – determines the number of meridians for a given isopter.
Size – Standard Goldmann stimulus size (I to V).
Brightness – Stimulus intensity can be selected within the range established for the specific requirements of the kinetic test.
Modifier – parameter that adjusts stimulus brightness according to a scale.
Color – Four stimulus colors are available: white, green, red, blue.
Speed – the stimulus moves along the isopter at a specified angular velocity.
Start angle – The angle marking the origin of the meridian, or the starting point of the stimulus movement.
End angle – The angle marking the end of the meridian, the point at which the stimulus completes its movement.
8 – Demo Start Button: Button for demonstration mode.
9 – Test Start Button: Starts the test.
10 – Pause/Resume Button: Press this button to temporarily pause the test.
11 – Close Button: Allows the test to be ended at any time and returns to the main program window.

Kinetic Test Results

The kinetic test results screen provides the following information and functions described below:
1 – Isopters: A field with drop-down lists that displays all parameters of a specific isopter and the patient’s responses to stimuli moved along designated meridians.
2 – Buttons A through H: The buttons correspond to the isopters evaluated sequentially (A – the first isopter, B – the second, H – the eighth). Pressing a specific button draws or fades the corresponding isopter on the screen. This option is particularly important when multiple isopters have been evaluated within a single kinetic test. Drawing all isopters simultaneously could make the graphical test result difficult to read. Each isopter is drawn using a different color that is permanently assigned.
3 – Print Button: For a kinetic test, only single-field printing is available. The printout will include the same graphical representation of the test results currently displayed on the screen. This allows separate printouts to be obtained for each isopter within a single test, if desired.
4 – Export Button: Allows data to be exported in one of the following selected formats: PDF, JPG/PNG, DICOM
5 – Next/Previous Study Buttons: These buttons allow navigation to the previous or next study in chronological order without the need to close the results window and manually select a study from the list.

A function that allows the user to define a customized test. This function is especially useful when only a specific portion of the patient’s visual field is of interest, such as an area where vision problems were previously detected during examinations. To begin editing a test, select the desired eye (1) and, if desired, the test field from which you wish to build a new test field (2). The test fields available by default are as follows: Central 22˚ Central 30˚ Driving Full Glaucoma Macula Peripheral Wide

A perimetric test is composed of a test field that reflects the extent of the visual field being examined and a strategy or algorithm used to evaluate the points within the test field. The following are the standard test fields available.

Peripheral Field Strategies (STRATEGIES)

Strategy 2 Zone (Strategy 2 Zone) – This is the fastest test strategy available in the software. Before the test begins, initial brightness levels are assigned to all points in the field. These levels are determined based on the age norm corresponding to the patient’s age.

Strategy 3 Zone (Strategy 3 Zone) – Very similar to the Strategy 2 Zone. The assignment of initial brightness levels to the points of the evaluated field is performed in the same manner as in Strategy 2 Zone. The program does not evaluate retinal sensitivity for the four yellow calibration points.

Quantify Defect Strategy (Quantify Defect) – This is a simplified version of the Screening strategy. The assignment of initial brightness levels to the test field points is performed in the same manner as in Strategy 2 Zone. The program does not perform a pre-calibration of brightness levels for the four yellow calibration points.

Screening Strategy (Screening Strategy) – This is a standard suprathreshold strategy. The first step of the strategy consists of determining retinal sensitivity at four calibration points. The calibration points are marked in yellow. The calibration of the four test points is performed according to the Threshold strategy. The initial brightness level of the calibration points is taken in accordance with the age norm. Point calibration is not performed if the norm from a previously conducted test is used.

Neurological Strategy (Neurological strategy) – A neurological strategy based on the Screening strategy.

Fast Threshold Strategy (Fast Threshold strategy) – Provides results very similar to those of the Threshold strategy, while significantly reducing test duration, thereby improving the reliability of results. The test begins by determining the sensitivity of four calibration points using the threshold strategy.

Threshold Strategy (Threshold Strategy) – A standard threshold strategy with a flow identical to that of Fast Threshold, but without reference to an age norm. This results in a longer evaluation process. The results obtained are highly accurate and sensitivity is determined within ± 1 dB.

Fastscan Strategy (Fastscan strategy) – The Fastscan strategy follows the same flow as the standard suprathreshold strategy (Screening). The only difference is that half of the points in the selected field are evaluated. This reduces test duration but decreases the spatial resolution of the obtained result.

Binocular Strategy (Binocular strategy) – The Binocular strategy is used for binocular single vision testing. Both eyes are evaluated simultaneously and points are presented at maximum intensity (0 dB).

Fast Threshold BY Strategy (Fast Threshold BY strategy) – Proceeds in an identical manner to the Fast Threshold strategy, with the difference that the test is performed using blue stimuli and a size conforming to Goldmann V, with yellow background illumination enabled.

Threshold BY Strategy (Threshold BY strategy) – The standard Blue on Yellow Threshold strategy (Threshold BY – Blue on Yellow), with a flow identical to that of Fast Threshold BY, lacks reference to an age norm. This results in a longer evaluation process. The results obtained are highly accurate and sensitivity is determined within ± 1 dB.

Constant Strategy (Constant strategy) – The Constant strategy is identical to Strategy 2 Zone, with the difference that the test grid cells are filled with a constant value instead of values derived from the age norm.

Bi-Driving Strategy (Bi-Driving strategy) – The Bi-Driving strategy is used to perform a two-eye test using both extended fields (up to 80˚ right and left). In this strategy, the test field is automatically generated by the program and the user has no influence over its selection.

Smart Threshold Strategy (Smart Threshold strategy) – The Smart Threshold strategy involves evaluating particular cells of the field in the same manner as the Fast Threshold strategy, with the difference that initially half of the field cells are selected for evaluation.

Smart Threshold BY Strategy (Smart Threshold BY) – The Blue on Yellow Smart Threshold strategy (Smart Threshold BY – Blue on Yellow) is identical to the Smart Threshold strategy, with the difference that the test is performed using blue stimuli and a size conforming to Goldmann V, with yellow background illumination enabled.