Inaccurate Vertical Centering - Perkins Mk2 Manuel D'instructions

9.

Inaccurate Vertical Centering

3
Result
A semi circular ring
appears partly in the
upper half
The ring appears
completely in the
upper half
The ring appears
almost completely in
the upper half, and
partly cut in the
lower half
Two partly cut rings
appear, the larger
one in the upper half
Correct position: The
edges of both semi
circular rings meet
exactly in the centre
of the ocular
Fig 12
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Image in ocular Cause
The measuring prism is
not focused on the eye.
The eye is too far up.
The measuring prism is
not focused on the eye.
The eye is still too far up.
The measuring prism is
not focused on the eye.
The eye is still too far up.
The measuring prism is
not focused on the eye.
The eye is still too far up.
The measuring prism is
focused precisely on the
eye.
en
Correction
Move the tonometer
upwards.
Move the tonometer
upwards.
Move the tonometer
upwards.
Move the tonometer
upwards.
26