The Main Menu screen is the starting point for performing all tests. From here you select tests with one of two methods:
• Using test buttons.
• Using the test library.
For details on each test, see “Test Library,” on page 3-4. After a test is chosen, you enter patient data, as described in “Entering Patient Data,” on page 3-7.
Using Test Buttons is the most convenient method of selecting tests. Your HFA-II has test buttons that are preset with the most commonly used tests. However, you can change them to suit your clinical needs. See “Altering the Main Menu Screen,” on page 2-26.
All patients requiring near vision correction should use trial lenses while taking central field tests and the central portion of full field tests. For your convenience, the HFA II-i automatically calculates the proper trial lens for your patient, if you know the patient’s distance prescription and date of birth (refer to “Entering Patient Data,” on page 3-7).
If you are not using the automatic trial lens calculation, refer to the following guidelines for selecting trial lenses.
Guidelines For Trial Lens Selection:
- Ignore cylinders of 0.25D or less.
- For cylinder errors below 1.25 D use the spherical equivalent. Use the full cylinder correction for cylinder errors of 1.25 D or more.
- Refer to Table 3.5 for hyperopic or emmetropic patients, or Table 3.6 for myopic patients, to determine the power of the spherical trial lens that you need to use.
- Verify that the patient can see the fixation light clearly through the trial lens before beginning testing. Young myopes may need additional minus power if the target appears blurry to them, prior to beginning testing. Many 30-40 year olds may not need the full trial lens correction.
Test parameters are the testing conditions used during a test (e.g., stimulus size, test strategy, test speed, etc.). While the majority of patients are best examined using “standard” parameters (or default parameters), you can alter the parameter settings to tailor the test to meet particular patient needs.
One example of a test parameter is the fixation target which has four settings: central, small diamond, large diamond, and bottom LED. The central fixation light is the default target. It is suitable for most patients, but you can change it if the patient requires a larger target.
You can access the parameter setup screen in two ways:
• From the Start Test screen, using CHANGE PARAMETERS.
• From the Test in Progress and Pause screen. Note that during testing, you can change only test speed and fixation monitoring.
Perimetry results are critical in the management of glaucoma and other eye diseases. Yet, it can often be difficult to obtain quality results. Threshold tests are often demanding and uncomfortable for patients. They tie-up staff and tire out patients, thus decreasing test reliability. The SITA testing strategy is a major advance over the previous methods used.
Carl Zeiss Meditec developed the two separate SITA testing strategies with two separate goals:
- SITA Standard: The goal was to design a perimetric thresholding method which collects twice as much information per unit time as the original Humphrey Full Threshold standard algorithm. SITA Standard cuts the test time in half without compromising test reproducibility.
- SITA Fast: The goal was to design a thresholding method which collects twice as much information per unit time as FastPac. SITA Fast cuts the test time in half relative to FastPac, without compromising test reproducibility.
Tests Available with SITA:
Both SITA Standard and SITA Fast are designed to run with only these threshold tests:
• Central 10-2
• Central 24-2
• Central 30-2
• Peripheral 60-4
SITA-SWAP is designed to run with only the following threshold test:
• Central 24-2
Proper positioning of a patient’s test eye throughout the test process is crucial to obtaining good test results. To aid in accomplishing this task, all HFA II-i models feature a video eye monitor. This monitor, which is automatically visible on the Start of Test screen, enables you to view the patient’s test eye during testing to verify that the patient is fixating properly. As is shown above in the screen illustration, when the eye is centered properly, a “cross” or “plus sign” is visible in the middle of the patient’s pupil on the screen of the HFA II.
Use the video eye monitor to:
• Position the test eye in the center of the trial lens holder.
• Monitor the patient during testing.
Although your HFA II-i has a number of features described in this chapter to help monitor and maintain the patient’s fixation, it is still important to verify the fixation by viewing the eye in the video eye monitor. Staying with the patient and visually monitoring fixation will help create a more reliable test result. Observing the patient during the test and recording information about fixation is important for validating the test results.
The three controls on the video eye monitor are: a plus sign (+) to brighten the image, a minus sign (-) to dim the image, and an OFF button to turn off the eye monitor display. To re-display the monitor, press the upper-left EYE button.