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Modified Thorington Phoria
PURPOSE To measure the lateral and vertical phoria at near.
INDICATIONS
The Modified Thorington phoria test is an alternative to the von Graefe
test for the near lateral and vertical phoria measurements．Since it is a test
done in space，it is useful when the patient is unable to be tested behind
the phoropter．
EQUIPMENT
·Penlight．
·Maddox rod
·Thorington card．The spacing of the targets on this card is such that，at a 40 cm viewing distance, the separation between targets represents one prism diopter．There is a small hole in the center of the card．A pen1ight is held behind this hole to provide the light source．
SET-UP
·The patient wears his habitual near correction．
·The patient holds the Maddox rod over his right eye as follows：
a．for measuring the lateral phoria, the grooves on the Maddox rod are oriented horizontally．The patient sees a vertical streak．The Thorington card with the horizontal rows of targets is used．
b．for measuring the vertical phoria, the grooves on the Maddox rod are oriented vertically．The patient sees a horizontal streak．The Thorington card with the vertical rows of targets is used．
·The Thorington card is held at 40 cm with a penlight behind the hole in the center of the card．
STEP-BY-STEP PROCEDURE
1．Instruct the patient to look at the light in the center of the card．
2．Instruct the patient to tell you the location of the streak relative to the light：left, right，or through the light for the lateral phoria (see Figure 4-23)；，down，or through the light for the vertical phoria(see Figure 4-24)．
For the horizontal phoria, if the streak is through the light，the patient has no deviation(orthophoria)．If the streak is to the right of the light，the patient has an esophoria．If the streak is to the left of the light，the patient has an exophoria．
For the vertical phoria，if the streak is through the light, the patient has no deviation (orthophoria)．If the streak is above the light，the patient has a left hyperphoria．If the streak is below the light, the patient has a right hyperphoria．
3．To determine the size of the phoria，ask the patient to tell you the target closest to which the streak passes．
RECORDING
·Record the size and the direction of the phoria．
EXAMPLE
·NLP/NVP by Modified Thorington：NLP 6Δ ex0／NVP 2A left hyper
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