CYCLODUCTION TEST
MADE WITH THE COMBINED USE OF THE TWO MADDOX RODS
Having determined that cyclophoria exists, as previously outlined,
the next step would be to make a cycloduction test, or a test of the
oblique muscles individually. Maddox rods, both red and white, should
be placed in position with the rods horizontal—the plus and minus sign
at 90 degrees on the scale (Fig. 37). The patient’s attention should
be directed to the usual muscle-testing spot of light, when a vertical
band of light will appear to the patient, as shown in Fig. 38.
[Illustration: Fig. 37—(A. and B.)—Primary position of combined use of
both Maddox rods for determining cycloduction test.]
[Illustration: _FIG. 38_
_NORMAL_]
[Illustration: _FIG. 39_
_RIGHT +CYCLODUCTION_
_LEFT -CYCLODUCTION_]
[Illustration: _FIG. 40_
_RIGHT -CYCLODUCTION_
_LEFT +CYCLODUCTION_
Figs. 38-40—Diagram showing position of streaks produced by Maddox rods
as they appear to patients in making cycloduction tests.]
To measure the duction range of the inferior oblique of the right eye,
it is merely necessary to slowly rotate the Maddox rod before the right
eye upward at its nasal end to the point where the band of light breaks
so as to resemble a letter “X”. This gives in degrees the amount of
right plus cycloduction, as indicated on the temporal scale, when it
will appear to the patient, as shown in Fig. 39.
The Maddox rod should then be restored to its original position, with
the plus and minus on the 90 degree line of the scale (Fig. 37), and
rotated upward at the temporal end until it again takes the form of the
letter “X”. (Fig. 40.) The position of the indicator will now denote
the amount of right minus cycloduction, or duction range of the right
superior oblique muscles. Having determined the duction range of the
oblique muscles of the patient’s right eye, both Maddox rods should be
placed in original position with rods horizontal and plus and minus
sign on 90° of scale, as shown in Fig. 37.
The Maddox rod before the left eye is then employed exactly in the
same manner as before when the test for the right eye was made. A plus
cycloduction of the left eye would be indicated, as shown in Fig. 40,
while a minus cycloduction of the left eye would appear to the patient,
as shown in Fig. 39.
By recording a comparison of each eye, as explained, it will be found
that the range of duction usually averages five to twenty degrees
on either side of the 90 degree line, as indicated on the scale
surrounding the Maddox rods.
It will be recalled that cyclophoria was only to be looked for in
oblique astigmatic cases. It is frequently possible to correct the
patient’s trouble, by changing the axis of the cylinder, before one or
both eyes, a minus cycloduction signifying a change of axis towards
180° while a plus toward 90°, according to the amount lacking in full
duction power. It is also well to exercise the oblique muscles through
a rotation of the Maddox rod before the affected eye, whether it be
one or both that is lacking in full duction power, until the required
amount is reached to equal its fellow member.
For a more exhaustive treatise the author suggests a reading of Dr.
Savage’s work on the subject.
TREATMENT FOR CYCLOPHORIA
As previously stated, it often proves of great benefit to employ a
muscular exercise where a patient has an existing cyclophoria of either
one or both eyes, results derivable through the exercise of the recti
muscles having been previously detailed.
To exercise the oblique muscles of the right eye, _both_ Maddox
rods should be placed in the original position employed for making
cycloduction test, as previously explained (Fig. 37). This causes the
patient to see but _one_ band or vertical streak (Fig. 38).
The Maddox rod, placed before the right eye, should be slowly rotated
inward from ninety degrees to a point on the scale where the single
streak of light breaks, when it should again be returned to ninety
degrees. This causes a contraction and relaxation of the muscles in
the form of an exercise and should be repeated ten times—about five
minutes each day. By employing the Maddox rod before the left eye in
precisely the same manner, its oblique muscles will be exercised.
To determine whether or not this form of exercise is beneficial to the
patient, the weekly cycloduction test, as previously described, should
be made and compared with the original findings.
[Illustration: _A Compact Phorometer and Trial-Frame._
SKI-OPTOMETER MODEL 235
For Testing and Correcting Muscular Imbalance—Providing a Comfortable
Form of Trial-Frame.]