Keeler D-KAT Z, Instructions For Use Manual

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19
EN
D-KAT Z-Type Tonometer by KEELER
10. ASTIGMATISM
If the cornea is spherical, measurements may be made along any meridian, but it is usual to
measure along the horizontal 0° meridian. This is not the case when measurements are made
on eyes affected by corneal astigmatism of greater than 3 dioptres, since the flattened areas
will not be circular but elliptical.
It has been calculated that in cases of more severe corneal astigmatism a surface area of
7,354 mm 2 (ø 3,06 mm) must be applanated; in this case the measuring prism forms an angle
of 43° to the meridian of the maximum radius.
For example:
For corneal astigmatism of 6.5mm / 30º= 52 diopters / 30º and 8.5mm / 120º = 40 diopters /
120º, the 120° prism value will be aligned with the 43° “A” mark on the prism support.
For corneal astigmatism of 8.5mm / 30º = 40 diopters / 30º and 6.5mm / 120º = 52 diopters /
120º, the 30° prism value will be aligned with the 43° “A” mark.
In other words, align the axial position of the major radius (that is, the axis of a negative
cylinder) with the prism value at the “A” mark on the prism support.
11. ROUTINE INSTRUMENT MAINTENANCE
Keeler recommends this routine maintenance be carried out by the user
frequently to ensure safe and accurate measurement. In the event of
the device being outside of the calibration tolerances, it is important to
send the device back to Keeler Ltd. or your local dealer for repair and
re-calibration.
0° marker
43° marker