The influence of heterophoria measurements on subsequent associated phoriameasurement in a refractive routine

The influence of measuring heterophoria on a subsequent associated phoria m easurement was investigated in 50 subjects. After refraction, heterophoria was measured by either von Graefe's technique or Maddox rod and wing. The e ffect of these procedures was assessed by associated phoria measurements ta ken before and after the dissociated measures. It is shown that subjects wi th a history of unstable binocular Vision are likely to have an associate p horia induced or changed by the previous dissociated phoria measurement, pa rticularly if von Graefe's technique is employed. It is recommended that, e specially for near, associated phoria should be assessed before the dissoci ated phoria in subjects who are regarded as having a history of unstable bi nocular vision. (C) 1999 The College of Optometrists. Published by Elsevier Science Ltd. All rights reserved.