The Maddox Phoria Measure is designed to measure Anisophoria which is the change in the phoria away from the primary position. Combines large 25mm aperture, a red maddox mounted perpendicular to the handle in a 10PD prism in a rotating disc withknurled edge. Small indicator in the periphery of the disc to indicate the effective prism power from 0PD to 10PD.
The large aperture allows measurement in all 9 cardinal fields with and without glasses. A penlight with a 1 or 2mm aperture is used as a light source, for near or far. The phoria measure should be held so that the maddox faces the patient. Theknurled disc is rotated clockwise or counterclockwise until the streak passes through the spot-light.
When the handle is held vertically the maddox rods are horizontal and the patient sees a vertical streak. If the patient fixates the spot-light with their left eye and looks through the phoria measure with their right eye and the notch is to the nasal side of the zero, the imbalance is right-exo. If it is to the temporal side of the zero the imbalance is right-eso. Conversely if the right eye isfixing the spot-light and the phoria measure is before the left eye, base in indicates left-exo and base out indicates left-eso.
When the handle is held horizontally the maddox rods are vertical and the patient sees a horizontal streak. If the patient fixates the spot-light with their left eye and looks through the phoria measure with their right eye and the notch is below the horizontal, the imbalance is right-hyper. If it is above the horizontal, the imbalance is right-hypo. Conversely if the right eye is fixing the spot-light and the phoria measure is before the left eye, base down indicates left-hyper and base up indicates left-hypo.
If the total imbalance is greater than 10PD, a hand-held prism is held before the opposite eye and the power is combined with that of the phoria measure to obtain a complete measure.
In some cases home testing may be a worthwhile option wit the patient performing the test 2 or 3 times daily for a week and recording their results. This may help to optimize the value of any prescribed prism.
After the spectacles have been made up and properly adjusted to the patient, it is a good idea to again use the monocular maddox phoria measure to re-test the patient through the new glasses. If any significant residual exist, they should be re-tested again in a few weeks after adaption has had time to take place.