Welch Allyn 18200 Bedienungsanleitung Seite 6

B) Position yourself 2/3 meter (26") from the patient. This
distance implies a working lens of +1.50D (computed as the
reciprocal of working distance in meters). Working distance
and lens may be varied to suit the practitioner's needs. (In
this instruction book the 2/3 meter (26") working distance
is assumed. Different working distances can be used, but
remember to adjust for your working distance.)
C) With the refracting equipment in place, direct the patient's
attention to a fixation spot at 15 feet or more from the eye
and align the streak vertically.
Figure 2
No oblique astigmatism
D) Observe the "reflex" which will appear as in Figure 2,
providing no oblique astigmatism is present. If oblique
astigmatism is present, the reflex will appear more like
Figure 3, where the reflex does not appear vertical.
E) Move the vertical streak horizontally across the pupil and
back again and observe whether the reflex moves in the same
direction as the streak or in the opposite direction.
Figure 3
Oblique astigmatism
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