10. USING THE TONOMETER
10.1 CHOOSING THE MEASUREMENT MODE
The tonometer can operate in two modes:
Series mode
The series mode is especially useful in self-tonometry. In the series mode,
keeping the button pressed down (see Figure 16) initiates the measurement
function, and the tonometer takes six rapid measurements one after the
other to obtain the final IOP reading. The button must be pressed for at least
3 seconds.
Single mode
You can use the single mode to take individual measurements one at a time.
The single mode is especially useful for those patients who tend to blink
heavily. Here you press the measurement button briefly (1 second) for each of
the six measurements to obtain the final IOP reading (Figure 17).
10.2 ADJUSTING THE MEASUREMENT POSITION
The tonometer has two adjustable supports (see points 4 and 5 in Figure 1), one for
the forehead and one for the cheek, as shown in Figure 18. The supports are for
ensuring accurate measurement distance and alignment.
To adjust the measurement position for your patient:
1.
Adjust the supports using the adjustment wheels as shown in Figure 18.
2.
Keep the probe horizontal and pointing perpendicularly to the center of
the cornea.
3.
Set the distance between the tip of the probe and the center of the
cornea to be 4-8mm (5/32-5/16") as shown in Figure 19.
4.
Read the distance setting (forehead A•1, A•2, etc., cheek B•1, B•2, etc.)
between the arrows on the scale (see point 7 in Figure 2) of the supports
(see Figure 20), and write it down on a support position tag for the
patient.
5.
Do the same for the other eye as well unless only one eye needs
monitoring.
6.
Verify that the support positions are correct each and every time the
patient comes in for a clinic visit.
10.3 AUTOMATIC EYE RECOGNITION
The tonometer includes an automatic eye recognition system that identifies
which eye, right or left, you are measuring. The system has two infrared LED
transmitters just below the probe base and one infrared LED sensor above
the probe base, as in Figure 21. The right-hand transmitter sends invisible
infrared light to the right and the left-hand transmitter to the left. The infrared
light reflects from your nose to the sensor. The sensor knows from which
transmitter the reflected infrared light came, and thus which eye you are
measuring. The resulting eye indication is included in the data that you can
transfer to a PC, as described in the section 11.
EYE RECOGNITION COMPONENTS (Figure 21)
1.
Left and right infrared transmitter.
2.
Infrared sensor.
10.4 TAKING THE MEASUREMENTS
The probe will make a gentle and brief contact with the eye when you take the
measurement. No topical anesthetic is needed. The recommended frequency
of measurements is 3-4 daily with a maximum of 5-6.
To measure intraocular pressure:
1.
Check that the Measure light still flashes on the back panel.
2.
If the Measure light does not flash, press the power button and wait
until the Measure light illuminates again.
3.
The patient should look straight ahead at a specific point while keeping
eyes wide open as shown in Figure 22.
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