Employ Third Method—Use of Prisms for Constant Wear to effect treatment.
Prisms
1st. Where a case cannot be reduced through use of first two methods, as for example in a case of 6° of exophoria, prescribe ¼ of amount of imbalance (¼ × 6 = 1½°) for each eye—base in—or esophoria base out, hyperphoria base up on eye affected.
2nd. Advise patient to call every three months and make duction test ([Fig. 24]). If no improvement in condition, after wearing prisms six months, operative means is suggested.
Assume a case is benefited, reduce prism power according to rule; ¼D prism for each degree of imbalance.
Cyclophoria
This work being of a technical nature, it is deemed best for the reader to study Chapter [XIII] and [XIV].
Chapter XIII
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.