en
Inaccurate Horizontal Centering
9.
2
Result
The upper semi
circular ring appears
partly
The upper semi
circular ring appears
completely - the
lower ring partly
Correct position: The
edges of both semi
circular rings meet
exactly in the centre
of the ocular
The lower semi
circular ring appears
completely - the
upper ring partly
The lower semi
circular ring appears
partly
Fig 11
25
Image in ocular
Cause
The measuring prism is
not focused on the eye.
The eye is too far on
the right.
The measuring prism is
not focused on the eye.
The eye is still too far on
the right.
The measuring prism is
focused precisely on
the eye.
The measuring prism is
not focused on the eye.
The eye is still too far on
the left.
The measuring prism is
not focused on the eye.
The eye is too far on
the left.
Correction
Move the tonometer to
the right.
Move the tonometer to
the right.
Move the tonometer to
the left.
Move the tonometer to
the left.