CYCLOPHORIA
MADE WITH MADDOX RODS AND ROTARY PRISMS
Cyclophoria, a condition affecting the oblique muscles of the eye, is
caused by its rotation. It is detected in the following manner by the
combined use of the red and white Maddox rods and the rotary prism.
[Illustration: Fig. 29—Position of rotary prism for producing diplopia
in testing cyclophoria with prism placed at 8° base up.]
Darken the room and direct the patient’s attention to the usual
muscle-testing spot of light, located approximately twenty feet away
and on a direct plane with the patient’s eye. The optical correction,
if one is required, should always be left in place—just as in making
other previously described muscle tests.
The rotary prism should then be brought before the patient’s right eye
with the handle-pointing upward and with zero graduations horizontal.
The indicator or red line should then be rotated upward from zero to
eight upon the prism scale, creating the equivalent of a prism of
8 diopters with base up (Fig. 29). This normally caused diplopia,
although in some cases it may be necessary to place the prism at 10 or
12 degrees before diplopia is produced.
[Illustration: Fig. 30—(A. and B.)—First position of both Maddox rods
used in conjunction with Fig. 29 for determining cyclophoria.]
The red Maddox rod should then be brought into operative position
before the patient’s left eye (Fig. 30a) and the white Maddox rod
before the patient’s right eye, (Fig. 30b) setting each one so that
the rods lie in a vertical position with their white line on the large
red zero (0).
The patient should now see two separate and distinct streaks of light,
one appearing below the other.
[Illustration: _DETERMINING CYCLOPHORIA_
_RIGHT EYE_ _LEFT EYE_
_Fig. 31_ _Fig. 34_
_NO CYCLOPHORIA_ _NO CYCLOPHORIA_]
[Illustration: _Fig. 32_ _Fig. 35_
_+ CYCLOPHORIA_ _+ CYCLOPHORIA_]
[Illustration: _Fig. 33_ _Fig. 36_
_- CYCLOPHORIA_ _- CYCLOPHORIA_
Figs. 31-36—Diagram showing how streaks appear to patient, as produced
by the Maddox rods in testing for cyclophoria.]
Should there be no cyclophoria of the right eye, the streaks will
appear in a horizontal plane parallel to each other (Fig. 31).
Should the red streak appear horizontally to the left eye, and the
white streak seen by the right eye appear at an angle therewith,
cyclophoria of the right eye would be indicated (Fig. 32).
In brief, should the white streak dip towards the patient’s left side,
the case would be one of right _plus_ cyclophoria (Fig. 32); whereas
right _minus_ cyclophoria would be indicated should the white streak
dip to the patient’s _right_ side (Fig. 33).
Next, setting the rotary prism of 8 degrees, placed base up before the
patient’s left eye, the _red_ streak should appear below the _white_
one. Should the two streaks appear horizontally, parallel with each
other, there would be _no_ cyclophoria of the left eye (Fig. 34).
If, however, the upper or white streak should appear horizontal, and
the lower or red streak at an angle therewith dipping toward the
patient’s _right_ side, the left eye would be cyclophoric and the case
would be one of left _plus_ cyclophoria, as the chart indicates (Fig.
35).
Should the red streak dip in toward the patient’s _left_ side, left
_minus_ cyclophoria would be designated (Fig. 36).
The patient would instinctively describe, with pointed finger and hand
motion, the position of the “dipping” line just as one would describe a
spiral staircase. Should this test determine that no cyclophoria exists
in either eye, there would be no necessity for further tests.
Some authorities claim that both Maddox rods should be of the same
color, so as to more readily assist the patient to fuse the two
objects. If the reader so desires, he can readily place a red lens from
the trial-case in the forward cell of the instrument.
The characters _plus_ and _minus_ in cyclophoria merely refer to _plus_
as signifying a tendency toward the _temporal_ side; _minus_ indicating
a tendency toward the _nasal_ side. This has no bearing on “convex” and
“concave,” which are frequently designated as “plus” and “minus.”
The test for cyclophoria is particularly essential, proving of utmost
importance where the patient requires an astigmatic correction with the
cylinder axis in oblique meridian. The case should then be investigated
in every instance by making a thorough and separate test of each eye
for cyclophoria.
In a case where cyclophoria is determined, the trouble may be caused by
the functioning of _other_ muscles, through the drain of nerve force,
thus disturbing the harmony of _every_ muscle action.
Cyclophoria is frequently caused by an imbalance of two recti, giving
an oblique pull. In most cases, it is merely necessary to release the
torsion, as described in the following chapter.