Zeiss SL 120 Mode D'emploi page 48

14
Fig. 12 10x micrometer
eyepiece with linear and
angular scales
1
2
1 Gravity ball
2 Measuring edge
Fig. 13 Reading the inclination
Description
10x micrometer eyepiece with linear and angular scales
This eyepiece has a linear scale of 15 mm length graduated to 0.2 mm.
Use of this eyepiece requires the 8x position of the magnification
changer.
A TABO angle scale graduated to 2° provides determination of the
angle of inclination in fitting toric soft contact lenses. The angular
measurement requires not a definite position of the magnification
changer.
The contact lenses (fitted and prescription lenses) carry an index mark
on their periphery outside the "optical zone".
The contact lens will quickly take a preferred position by the natural
movement of the eye. The index mark on the lens will no longer agree
with the horizontal. This deviation, called inclination, is to be
determined.
Subtractive inclination:
The index mark, the so-called DS axis (DS = dynamic stabilization axis)
lies in the 1st quadrant of the TABO scheme, i.e. between 0° and
90°.
Additive inclination:
The DS axis lies in the 2nd quadrant (between 90° and 180°).
The special eyepiece has an angular scale graduated to 2° for the
measurement of the inclination angle.
A gravity ball (1, Fig. 13) produces the artificial horizon required for the
angular measurement.
Measurement process
•
Grasping the knurled ring, turn the entire eyepiece in the tube socket
until the continuous line of the linear scale coincides with the index
mark on the contact lens.
•
Read the value from the measuring edge (2, Fig. 13) of the gravity
ball. The inclination angle is displayed according to the TABO
scheme.
The reproducibility of the measurement is ±0.5°. When taking the
measurement, allow for a short settling time of the ball.
The image scale in the eyepiece plane is insignificant for the
measurement of the inclination angle. Select the magnification changer
setting of the slit lamp microscope only so as to obtain a sufficiently
large object field.
000000-1363-329 SL 120 11.07.2006