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JACKSON CROSS CYLINDER
SLIDES PREPARED BY
OPTOM FASLU MUHAMMED
 Cross cylinder is a type of toric lens used
during refraction also known as ‘flip
cylinder’. Its use was popularized by
Edward Jackson and it is often referred
to as Jackson’s cross cylinder.
 The cross cylinder is a Combination of
two cylinder of equal strength but with
opposite sign placed with their axis at
right angle to each other and mounted in
a handle.
 Principle of JCC is collapsing of the
sturms conoid.
 The cross cylinder is a sphero
cylindrical lens in which the power of
the cylinder is twice the power of the
sphere and of the opposite sign
 The lens is mounted on a handle
which is placed at 45 to the axes of
the cylinders
 The commonly used cross cylinders
are of +/- 0.25D and +/-0.50D.
JCC TEST
 Gives BVA done by fogging.
 The goal if astigmatism is present is to
place the circle of least confusion of
the sturms conoid on the retina thus
creating mixed astigmatism.
1. Discovering the astigmatism
 If no cylinder correction is present
initially, the cross cylinder placed
arbitrarily at 90 and180 degree to check
for astigmatism.
 If a preferred flip position is found , a
cylinder is added with axis parallel to the
respective plus or minus axis of the
cross cylinder until the two flip choices
are equal.
 If no preference is found with cross
cylinder axes at 90 and 180, the 45 and
135 should always be checked assuming
2. Refinement of the axis
 Always done first.
 Because the correct axis can be found in
the presence of an incorrect power but
the full cylinder power will not be found in
the presence of an incorrect axis.
 To check the axis, the cross cylinder is
held before the eye with its handle is
parallel with the axis of the trial cylinder
(i.e. with its axis at 45 degree to the axis
of cylinder in trail frame.)
 Pt is asked to tell about any change in the
VA, pt notices no difference b/w the two
positions - axis of the correcting cylinder in
the trial frame is correct.
 If VA is improved, cylinder correction is
present
 The cross cylinders is held in the preferred
position and the axis of the trial cylinder
rotated slightly towards the axis of the same
sign on the crossed cylinder
 The process is repeated until the trial cylinder
is in the correct axis for the eye clearer.
3. Refinement of cylinder
power
 Cross cylinder is placed with its axis
parallel to the axis of the cylinder in the
trial frame. First with same sign and then
opposite sign.
 VA is not change in either of the position
the power of the cylinder in the trial
frame is correct.
 If VA is improving in any position
corresponding correction should be
made and reverified till final correction is
attained.
NOTES PREPARED BY

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Jackson cross cylinder

  • 1. JACKSON CROSS CYLINDER SLIDES PREPARED BY OPTOM FASLU MUHAMMED
  • 2.  Cross cylinder is a type of toric lens used during refraction also known as ‘flip cylinder’. Its use was popularized by Edward Jackson and it is often referred to as Jackson’s cross cylinder.  The cross cylinder is a Combination of two cylinder of equal strength but with opposite sign placed with their axis at right angle to each other and mounted in a handle.  Principle of JCC is collapsing of the sturms conoid.
  • 3.
  • 4.  The cross cylinder is a sphero cylindrical lens in which the power of the cylinder is twice the power of the sphere and of the opposite sign  The lens is mounted on a handle which is placed at 45 to the axes of the cylinders  The commonly used cross cylinders are of +/- 0.25D and +/-0.50D.
  • 5. JCC TEST  Gives BVA done by fogging.  The goal if astigmatism is present is to place the circle of least confusion of the sturms conoid on the retina thus creating mixed astigmatism.
  • 6. 1. Discovering the astigmatism  If no cylinder correction is present initially, the cross cylinder placed arbitrarily at 90 and180 degree to check for astigmatism.  If a preferred flip position is found , a cylinder is added with axis parallel to the respective plus or minus axis of the cross cylinder until the two flip choices are equal.  If no preference is found with cross cylinder axes at 90 and 180, the 45 and 135 should always be checked assuming
  • 7. 2. Refinement of the axis  Always done first.  Because the correct axis can be found in the presence of an incorrect power but the full cylinder power will not be found in the presence of an incorrect axis.  To check the axis, the cross cylinder is held before the eye with its handle is parallel with the axis of the trial cylinder (i.e. with its axis at 45 degree to the axis of cylinder in trail frame.)
  • 8.  Pt is asked to tell about any change in the VA, pt notices no difference b/w the two positions - axis of the correcting cylinder in the trial frame is correct.  If VA is improved, cylinder correction is present  The cross cylinders is held in the preferred position and the axis of the trial cylinder rotated slightly towards the axis of the same sign on the crossed cylinder  The process is repeated until the trial cylinder is in the correct axis for the eye clearer.
  • 9. 3. Refinement of cylinder power  Cross cylinder is placed with its axis parallel to the axis of the cylinder in the trial frame. First with same sign and then opposite sign.  VA is not change in either of the position the power of the cylinder in the trial frame is correct.  If VA is improving in any position corresponding correction should be made and reverified till final correction is attained.